tag:blogger.com,1999:blog-47647253226783131102024-03-19T05:26:13.215-07:00Entomology For StudentsThis blog contain notes, presentations, media, movies, diagrams, images and many more things for insect learners. for the entomology course in university and colleges i have placed study material here, it is collected from the famous books and web resources for student purpose, it involve no earning, it is a free service for the student of my planet. Student may ask queries here.DR. LAXMIKANT B. DAMAhttp://www.blogger.com/profile/13198225293462944168noreply@blogger.comBlogger14125tag:blogger.com,1999:blog-4764725322678313110.post-16521759995949405272013-07-10T04:43:00.002-07:002013-07-10T04:45:26.234-07:00Thermoregulation in insect<div dir="ltr" style="text-align: left;" trbidi="on">
<!--[if gte mso 9]><xml>
<o:OfficeDocumentSettings>
<o:AllowPNG/>
</o:OfficeDocumentSettings>
</xml><![endif]--><br />
<!--[if gte mso 9]><xml>
<w:WordDocument>
<w:View>Print</w:View>
<w:Zoom>FullPage</w:Zoom>
<w:TrackMoves/>
<w:TrackFormatting/>
<w:PunctuationKerning/>
<w:DrawingGridHorizontalSpacing>9.05 pt</w:DrawingGridHorizontalSpacing>
<w:DrawingGridVerticalSpacing>9.05 pt</w:DrawingGridVerticalSpacing>
<w:ValidateAgainstSchemas/>
<w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid>
<w:IgnoreMixedContent>false</w:IgnoreMixedContent>
<w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText>
<w:DoNotPromoteQF/>
<w:LidThemeOther>EN-IN</w:LidThemeOther>
<w:LidThemeAsian>X-NONE</w:LidThemeAsian>
<w:LidThemeComplexScript>X-NONE</w:LidThemeComplexScript>
<w:Compatibility>
<w:BreakWrappedTables/>
<w:SnapToGridInCell/>
<w:WrapTextWithPunct/>
<w:UseAsianBreakRules/>
<w:DontGrowAutofit/>
<w:SplitPgBreakAndParaMark/>
<w:EnableOpenTypeKerning/>
<w:DontFlipMirrorIndents/>
<w:OverrideTableStyleHps/>
</w:Compatibility>
<m:mathPr>
<m:mathFont m:val="Cambria Math"/>
<m:brkBin m:val="before"/>
<m:brkBinSub m:val="--"/>
<m:smallFrac m:val="off"/>
<m:dispDef/>
<m:lMargin m:val="0"/>
<m:rMargin m:val="0"/>
<m:defJc m:val="centerGroup"/>
<m:wrapIndent m:val="1440"/>
<m:intLim m:val="subSup"/>
<m:naryLim m:val="undOvr"/>
</m:mathPr></w:WordDocument>
</xml><![endif]--><!--[if gte mso 9]><xml>
<w:LatentStyles DefLockedState="false" DefUnhideWhenUsed="true"
DefSemiHidden="true" DefQFormat="false" DefPriority="99"
LatentStyleCount="267">
<w:LsdException Locked="false" Priority="0" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Normal"/>
<w:LsdException Locked="false" Priority="9" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="heading 1"/>
<w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 2"/>
<w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 3"/>
<w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 4"/>
<w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 5"/>
<w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 6"/>
<w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 7"/>
<w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 8"/>
<w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 9"/>
<w:LsdException Locked="false" Priority="39" Name="toc 1"/>
<w:LsdException Locked="false" Priority="39" Name="toc 2"/>
<w:LsdException Locked="false" Priority="39" Name="toc 3"/>
<w:LsdException Locked="false" Priority="39" Name="toc 4"/>
<w:LsdException Locked="false" Priority="39" Name="toc 5"/>
<w:LsdException Locked="false" Priority="39" Name="toc 6"/>
<w:LsdException Locked="false" Priority="39" Name="toc 7"/>
<w:LsdException Locked="false" Priority="39" Name="toc 8"/>
<w:LsdException Locked="false" Priority="39" Name="toc 9"/>
<w:LsdException Locked="false" Priority="35" QFormat="true" Name="caption"/>
<w:LsdException Locked="false" Priority="10" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Title"/>
<w:LsdException Locked="false" Priority="1" UnhideWhenUsed="false"
Name="Default Paragraph Font"/>
<w:LsdException Locked="false" Priority="11" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Subtitle"/>
<w:LsdException Locked="false" Priority="22" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Strong"/>
<w:LsdException Locked="false" Priority="20" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Emphasis"/>
<w:LsdException Locked="false" Priority="59" SemiHidden="false"
UnhideWhenUsed="false" Name="Table Grid"/>
<w:LsdException Locked="false" UnhideWhenUsed="false" Name="Placeholder Text"/>
<w:LsdException Locked="false" Priority="1" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="No Spacing"/>
<w:LsdException Locked="false" Priority="60" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Shading"/>
<w:LsdException Locked="false" Priority="61" SemiHidden="false"
UnhideWhenUsed="false" Name="Light List"/>
<w:LsdException Locked="false" Priority="62" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Grid"/>
<w:LsdException Locked="false" Priority="63" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 1"/>
<w:LsdException Locked="false" Priority="64" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 2"/>
<w:LsdException Locked="false" Priority="65" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 1"/>
<w:LsdException Locked="false" Priority="66" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 2"/>
<w:LsdException Locked="false" Priority="67" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 1"/>
<w:LsdException Locked="false" Priority="68" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 2"/>
<w:LsdException Locked="false" Priority="69" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 3"/>
<w:LsdException Locked="false" Priority="70" SemiHidden="false"
UnhideWhenUsed="false" Name="Dark List"/>
<w:LsdException Locked="false" Priority="71" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Shading"/>
<w:LsdException Locked="false" Priority="72" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful List"/>
<w:LsdException Locked="false" Priority="73" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Grid"/>
<w:LsdException Locked="false" Priority="60" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Shading Accent 1"/>
<w:LsdException Locked="false" Priority="61" SemiHidden="false"
UnhideWhenUsed="false" Name="Light List Accent 1"/>
<w:LsdException Locked="false" Priority="62" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Grid Accent 1"/>
<w:LsdException Locked="false" Priority="63" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 1 Accent 1"/>
<w:LsdException Locked="false" Priority="64" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 2 Accent 1"/>
<w:LsdException Locked="false" Priority="65" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 1 Accent 1"/>
<w:LsdException Locked="false" UnhideWhenUsed="false" Name="Revision"/>
<w:LsdException Locked="false" Priority="34" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="List Paragraph"/>
<w:LsdException Locked="false" Priority="29" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Quote"/>
<w:LsdException Locked="false" Priority="30" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Intense Quote"/>
<w:LsdException Locked="false" Priority="66" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 2 Accent 1"/>
<w:LsdException Locked="false" Priority="67" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 1 Accent 1"/>
<w:LsdException Locked="false" Priority="68" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 2 Accent 1"/>
<w:LsdException Locked="false" Priority="69" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 3 Accent 1"/>
<w:LsdException Locked="false" Priority="70" SemiHidden="false"
UnhideWhenUsed="false" Name="Dark List Accent 1"/>
<w:LsdException Locked="false" Priority="71" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Shading Accent 1"/>
<w:LsdException Locked="false" Priority="72" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful List Accent 1"/>
<w:LsdException Locked="false" Priority="73" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Grid Accent 1"/>
<w:LsdException Locked="false" Priority="60" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Shading Accent 2"/>
<w:LsdException Locked="false" Priority="61" SemiHidden="false"
UnhideWhenUsed="false" Name="Light List Accent 2"/>
<w:LsdException Locked="false" Priority="62" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Grid Accent 2"/>
<w:LsdException Locked="false" Priority="63" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 1 Accent 2"/>
<w:LsdException Locked="false" Priority="64" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 2 Accent 2"/>
<w:LsdException Locked="false" Priority="65" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 1 Accent 2"/>
<w:LsdException Locked="false" Priority="66" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 2 Accent 2"/>
<w:LsdException Locked="false" Priority="67" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 1 Accent 2"/>
<w:LsdException Locked="false" Priority="68" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 2 Accent 2"/>
<w:LsdException Locked="false" Priority="69" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 3 Accent 2"/>
<w:LsdException Locked="false" Priority="70" SemiHidden="false"
UnhideWhenUsed="false" Name="Dark List Accent 2"/>
<w:LsdException Locked="false" Priority="71" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Shading Accent 2"/>
<w:LsdException Locked="false" Priority="72" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful List Accent 2"/>
<w:LsdException Locked="false" Priority="73" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Grid Accent 2"/>
<w:LsdException Locked="false" Priority="60" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Shading Accent 3"/>
<w:LsdException Locked="false" Priority="61" SemiHidden="false"
UnhideWhenUsed="false" Name="Light List Accent 3"/>
<w:LsdException Locked="false" Priority="62" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Grid Accent 3"/>
<w:LsdException Locked="false" Priority="63" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 1 Accent 3"/>
<w:LsdException Locked="false" Priority="64" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 2 Accent 3"/>
<w:LsdException Locked="false" Priority="65" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 1 Accent 3"/>
<w:LsdException Locked="false" Priority="66" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 2 Accent 3"/>
<w:LsdException Locked="false" Priority="67" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 1 Accent 3"/>
<w:LsdException Locked="false" Priority="68" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 2 Accent 3"/>
<w:LsdException Locked="false" Priority="69" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 3 Accent 3"/>
<w:LsdException Locked="false" Priority="70" SemiHidden="false"
UnhideWhenUsed="false" Name="Dark List Accent 3"/>
<w:LsdException Locked="false" Priority="71" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Shading Accent 3"/>
<w:LsdException Locked="false" Priority="72" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful List Accent 3"/>
<w:LsdException Locked="false" Priority="73" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Grid Accent 3"/>
<w:LsdException Locked="false" Priority="60" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Shading Accent 4"/>
<w:LsdException Locked="false" Priority="61" SemiHidden="false"
UnhideWhenUsed="false" Name="Light List Accent 4"/>
<w:LsdException Locked="false" Priority="62" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Grid Accent 4"/>
<w:LsdException Locked="false" Priority="63" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 1 Accent 4"/>
<w:LsdException Locked="false" Priority="64" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 2 Accent 4"/>
<w:LsdException Locked="false" Priority="65" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 1 Accent 4"/>
<w:LsdException Locked="false" Priority="66" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 2 Accent 4"/>
<w:LsdException Locked="false" Priority="67" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 1 Accent 4"/>
<w:LsdException Locked="false" Priority="68" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 2 Accent 4"/>
<w:LsdException Locked="false" Priority="69" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 3 Accent 4"/>
<w:LsdException Locked="false" Priority="70" SemiHidden="false"
UnhideWhenUsed="false" Name="Dark List Accent 4"/>
<w:LsdException Locked="false" Priority="71" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Shading Accent 4"/>
<w:LsdException Locked="false" Priority="72" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful List Accent 4"/>
<w:LsdException Locked="false" Priority="73" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Grid Accent 4"/>
<w:LsdException Locked="false" Priority="60" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Shading Accent 5"/>
<w:LsdException Locked="false" Priority="61" SemiHidden="false"
UnhideWhenUsed="false" Name="Light List Accent 5"/>
<w:LsdException Locked="false" Priority="62" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Grid Accent 5"/>
<w:LsdException Locked="false" Priority="63" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 1 Accent 5"/>
<w:LsdException Locked="false" Priority="64" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 2 Accent 5"/>
<w:LsdException Locked="false" Priority="65" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 1 Accent 5"/>
<w:LsdException Locked="false" Priority="66" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 2 Accent 5"/>
<w:LsdException Locked="false" Priority="67" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 1 Accent 5"/>
<w:LsdException Locked="false" Priority="68" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 2 Accent 5"/>
<w:LsdException Locked="false" Priority="69" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 3 Accent 5"/>
<w:LsdException Locked="false" Priority="70" SemiHidden="false"
UnhideWhenUsed="false" Name="Dark List Accent 5"/>
<w:LsdException Locked="false" Priority="71" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Shading Accent 5"/>
<w:LsdException Locked="false" Priority="72" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful List Accent 5"/>
<w:LsdException Locked="false" Priority="73" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Grid Accent 5"/>
<w:LsdException Locked="false" Priority="60" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Shading Accent 6"/>
<w:LsdException Locked="false" Priority="61" SemiHidden="false"
UnhideWhenUsed="false" Name="Light List Accent 6"/>
<w:LsdException Locked="false" Priority="62" SemiHidden="false"
UnhideWhenUsed="false" Name="Light Grid Accent 6"/>
<w:LsdException Locked="false" Priority="63" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 1 Accent 6"/>
<w:LsdException Locked="false" Priority="64" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Shading 2 Accent 6"/>
<w:LsdException Locked="false" Priority="65" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 1 Accent 6"/>
<w:LsdException Locked="false" Priority="66" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium List 2 Accent 6"/>
<w:LsdException Locked="false" Priority="67" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 1 Accent 6"/>
<w:LsdException Locked="false" Priority="68" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 2 Accent 6"/>
<w:LsdException Locked="false" Priority="69" SemiHidden="false"
UnhideWhenUsed="false" Name="Medium Grid 3 Accent 6"/>
<w:LsdException Locked="false" Priority="70" SemiHidden="false"
UnhideWhenUsed="false" Name="Dark List Accent 6"/>
<w:LsdException Locked="false" Priority="71" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Shading Accent 6"/>
<w:LsdException Locked="false" Priority="72" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful List Accent 6"/>
<w:LsdException Locked="false" Priority="73" SemiHidden="false"
UnhideWhenUsed="false" Name="Colorful Grid Accent 6"/>
<w:LsdException Locked="false" Priority="19" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Subtle Emphasis"/>
<w:LsdException Locked="false" Priority="21" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Intense Emphasis"/>
<w:LsdException Locked="false" Priority="31" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Subtle Reference"/>
<w:LsdException Locked="false" Priority="32" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Intense Reference"/>
<w:LsdException Locked="false" Priority="33" SemiHidden="false"
UnhideWhenUsed="false" QFormat="true" Name="Book Title"/>
<w:LsdException Locked="false" Priority="37" Name="Bibliography"/>
<w:LsdException Locked="false" Priority="39" QFormat="true" Name="TOC Heading"/>
</w:LatentStyles>
</xml><![endif]--><!--[if gte mso 10]>
<style>
/* Style Definitions */
table.MsoNormalTable
{mso-style-name:"Table Normal";
mso-tstyle-rowband-size:0;
mso-tstyle-colband-size:0;
mso-style-noshow:yes;
mso-style-priority:99;
mso-style-parent:"";
mso-padding-alt:0cm 5.4pt 0cm 5.4pt;
mso-para-margin-top:0cm;
mso-para-margin-right:0cm;
mso-para-margin-bottom:10.0pt;
mso-para-margin-left:0cm;
line-height:115%;
mso-pagination:widow-orphan;
font-size:11.0pt;
font-family:"Calibri","sans-serif";
mso-ascii-font-family:Calibri;
mso-ascii-theme-font:minor-latin;
mso-hansi-font-family:Calibri;
mso-hansi-theme-font:minor-latin;
mso-bidi-font-family:"Times New Roman";
mso-bidi-theme-font:minor-bidi;
mso-fareast-language:EN-US;}
</style>
<![endif]-->
<br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<h2 style="text-align: left;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 28.5pt; letter-spacing: -1.0pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman"; mso-font-width: 70%;">Thermoregulation in Insect</span></b></h2>
</div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Bemd Heinrich</span></b><span style="mso-bookmark: bookmark1;"></span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<i><span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 8.0pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">University
of Vermont</span></i><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<br />
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">In
insects, as in other animals, body temperature strongly affects the rate of
energy expenditure, the rate at which food can be located and harvested,
growth, the facility with which mates can be acquired and predators avoided,
and sometimes also the susceptibility to disease organisms. Thermoregulation
refers to the ability to regulate that body temperature which best serves
survival and reproduction, and it encompasses numerous conflicting constraints
and selective pressures. In insects, major considerations involve body mass and
access to either external or internal heat. Thermoregulation operates through
behavior, physiology, and morphology. For the most part, insects are too small
to be able to appreciably elevate, or regulate, their body temperature by
internal heat production, although some are large enough and that, coupled with
their high flight metabolism, could easily cause them to overheat. In numerous
insects, elaborate mechanisms of thermoregulation have evolved both for
heating and for cooling the body that possibly rival those of the typically
endothermic vertebrates.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<br />
<a href="http://www.blogger.com/null" name="bookmark2"><b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">ENDOTHERMY IN FLYING INSECTS</span></b></a><span style="mso-bookmark: bookmark2;"></span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="text-align: justify;">
<br />
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; line-height: 115%; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Insects arose on earth at least 350 mya
in the Devonian Period of the Paleozoic Era. Little is known about the earliest
forms, except that originally they must have been crawlers, not flyers, and
their bodies assumed approximately the temperature of the immediate
surroundings to which they adapted. This holds true even when the immediate
surroundings are quite frigid. The adult form of a flightless midge (<i>Diamesa</i>
sp.) walks on glacier ice even when its body temperature is chilled to — 16°C.
It is so sensitive to heat that, when taken from its natural environment and
held in one’s hand, it is killed by the warmth of one’s skin. However, there
are insects that maintain quite specific and high body temperatures. Some
species of sphinx moths, for example, have thick insulating fur and normally
maintain a thoracic temperature near 46°C during flight over a wide range of
ambient temperatures. To these moths, our own normal body temperature of 37°C
is almost cool. An insect’s head and abdominal temperatures are for the most
part unregulated.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">In the
same way that the motor heats up when a car burns fuel, heat is released as an
inevitable by-product of cellular metabolism whenever muscle contracts. Close
to 94% of the energy expended by muscles during contraction is degraded to
heat, while approximately 6% appears as mechanical force on the wings. Insect
flight is one of the most energetically demanding activities known, and thus
most insects produce more heat per unit muscle mass when they fly than almost
any organism on earth. Most insects exist under conditions somewhere in between
the cold-blooded crawler and the hot- blooded flyer, but these extremes show us
what is possible, and they thus offer us a remarkable window into thermal
adaptation from an evolutionary perspective.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">The ability
of birds and mammals to regulate body temperature at one set point,
specifically 37—4l°C, has long been considered proof of sophistication and
phylogenetic advancement relative to animals whose body temperature varies
with that of their environment. Deviation of body temperature from the set
point of 37—4l°C is, in birds and mammals, often associated with illness and
was once thought to be caused by a failure of the thermoregulatory system. We
now know that both increases and decreases in body temperature can be and often
are adaptive responses. Both responses are often sophisticated physiological
mechanisms that involve more thermoregulation rather than less, albeit the
body is kept at a more appropriate temperature for specific conditions.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Small
insects have much lower body temperatures in flight than large insects, not
because they produce less heat—in fact, they may have <i>higher</i> rates of
heat production than larger insects, but because they have much greater
conductance because of their large relative surface area. In bees, for example,
only the large species heat up in flight and generate an appreciable elevation
of body temperature even though metabolic cost of flight per unit weight
declines approximately 230% for a 10-fold increase in mass. A mosquito in
flight maintains only a tiny (<1 a="" ambient="" amounts="" and="" between="" blow="" despite="" fly="" gradient="" heat="" i="" of="" prodigious="" production.="" temperature="" thoracic="">(Calliphora
vicia)<!--1--></1></span></div>
may heat up 5°C, and a honey bee heats up its thorax about 15°C.
Having a much larger thorax, and hence a smaller relative surface area, means
that the internally generated heat during flight is not lost by convection at
the same rate that it is produced until a much higher temperature gradient has
been generated.<span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span>
<br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Large
insects—those that inevitably generate a high body temperature during
continuous flight—must be biochemically adapted to operate their flight muscles
at the high temperatures experienced. Temperature is important for mechanical
efficiency; at low muscle temperature there is partial overlap in contractions
of the up- and downstroke muscles, the</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">dorsoventral
and dorsal longitudinal muscles; the two sets of muscles then work against each
other rather than working to move the wings.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Numerous
other moths—such as most microlepidoptera and geometrids (inchworms) and some
ctenuchids and arctiids—are small or weak flyers that do not heat up but fly at
low air temperature. They fly at muscle temperatures much lower even than those
at which the large-bodied, small-winged (and hot-blooded) sphinx moths generate
zero power. Evolution has acted strongly to tailor the flight motor’s capacity
for maximum power output for much lower ranges of operating temperatures. For
example, the geometrid <i>Operophtera bruceata </i>can gain sufficient power to
fly at 0°C. (Nevertheless, its capacity to do so is only partially the result
of muscle physiology.)</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">The basis
for the evolution of differences between species arising from a common ancestor
is variation among individuals. Variation was present in the past, and for
many traits, variation is maintained even now. For example, in <i>Colias </i>(sulphur)
butterflies, the gene locus for phosphoglucose isomerase, one of the enzymes
involved in energy metabolism in these butterflies, changes in allele frequency
with season and habitat temperature. This suggests that natural selection is
occurring even over very short (that is, seasonal) time spans. The different
enzyme alleles have different thermal stabilities, and heterozygotes are
thought to have an advantage in an environment of rapidly fluctuating
temperatures inasmuch as the individuals heterozygotic for this locus fly over
a range of temperatures broader than that of individuals of other genotypes.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">When a
seasonally changing temperature environment, which is the rule, can select for
heterozygosity, then one might expect that an environment of constantly high or
low temperature, which is the exception, should lead to the fixation of an
appropriate genotype. Hence, selection in terms of gene-frequency changes would
not normally be present for our inspection in more constant environments, in
which appropriate genotypes would already have been selected long ago to adapt
to the average temperature. The specific thoracic temperature that is
maintained by regulation is “chosen” by evolution probably because it is the
temperature most readily regulated for maximum activity over a range of
prevailing environmental conditions.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">WARM-UP BY
SHIVERING</span></b><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; line-height: 115%; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">During his classic studies of honey bee
communication, Karl von Frisch noted that bees often interrupted flight for a
few minutes when they were returning to the hive heavily laden with nectar. He
presumed they stopped “to rest,” but we now know they were stopping to work: to
raise their thoracic temperature. They most likely stopped flight because it
was a cold day and they had cooled convectively. Bees are able to raise their
thoracic temperature by shivering, which can work their flight muscles harder
than flight itself does. Von Frisch could not have known any of this, because
shivering and thermoregulation by individual insects was unknown in the 1960s,
nor is shivering externally visible in bees even if one looks very closely.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Like the
maintenance of an elevated body temperature by internal heat production in
flight, physiological warm-up is found in all large, active flyers among the
dragonflies (Odonata), moths and butterflies (Lepidoptera), katydids
(Orthoptera), cicadas (Clypeorrhyncha or Homoptera), flies (Diptera), beetles
(Coleoptera), and wasps and bees (Hymenoptera). That is, it is found from some
of the earliest forms, the Odonata, to the most evolutionarily highly derived,
the Diptera, Coleoptera, and Hymenoptera. It is not found in the small and
therefore nonendothermic members of the same groups. Because no insects shiver
except those that then also heat up from flight metabolism, it seems reasonable
to conclude that the evolution of shivering behaviors is related to the
evolution of flight but is unrelated to the insect’s place on the phylogenic
tree.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">During
preflight warm-up, there are synchronous contractions of groups of muscles
that normally contract alternately in flight. That is, the main wing-depressor
muscles, the dorsal longitudinal muscles, are excited simultaneously—in other
words, in synchrony—with the dorsoventral wing elevator muscles. The neural
activation pattern of thoracic flight muscles needs to be and is already very
labile for flight control, and to add shivering when flight behavior has
already evolved is probably a very minor evolutionary step. Physiological warmup
in its most basic form is like the idling of an engine; the engine “evolved” to
propel the car, not to warm it up. Once present, the heat-producing flight
muscle system required only a slight modification of neuronal activation
patterns and, in the more sophisticated models, also the addition of the biological
equivalent of a clutch—a mechanism to disengage the wings in the same way that
an automotive clutch disengages the car’s wheels. Some insects, such as
dragonflies and moths, do have visible external wing vibrations that were
originally called “wing whirring,” these were once thought to pump air into the
animal before the true function was elucidated.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">The zenith
of the shivering response of any hot-blooded animal (vertebrate as well as
invertebrate) belongs to some bees. Honey bees and bumble bees have a
physiological sophistication either not existing or not yet observed in other
insects, and they exploit shivering behavior to an unprecedented extent and in
a variety of ways. Like flies and beetles, bees are “myogenic” flyers in which
the wing-beat cycle runs in part on automatic; as the downstroke muscles
contract they stretch the upstroke muscles. This stretching <i>by itself</i>
causes the upstroke muscles to contract. The downstroke of the wing therefore
automatically causes the upstroke muscles to contract and vice versa, in a
repeating cycle that is sparked by neural commands that are at a much lower
frequency than the wing beats and are no longer specific to a single wing beat.
(This system permits some of the smallest insects, such as midges, to achieve
the unprecedented coordination required for wing-stroke cycles of over 1000
beats per second.) But the stretching of opposing muscle groups that maintains
the myogenic contraction cycle can occur only if the wings are actually
beating—namely,</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">during
flight. When the wings are not in use, as when they are folded back dorsally
and the clutch-like wing hinge is engaged, then the muscle groups are in near
tetanus. That is the reason for the bees’ shivering.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Very
vigorous shivering in bees is physically dampened even more by yet another
mechanism. One of the two sets of opposite- acting muscles is activated (and
hence contracted) slightly more than the other. Because the opposing muscles
act like weights forcing down each side of a seesaw, the added force on one set
of muscles prevents the “seesaw” from working (and the wings from “vibrating”
back and forth).</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">WARM-UP BY
BASKING</span></b><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Like
warm-up by shivering, warm-up by basking occurs in all major orders of insects
that have fast flyers large enough to heat up from their flight metabolism. In
its simplest form, behavioral warm-up is merely heat-seeking. A basking insect
usually takes specific postures that simultaneously maximize solar input and
minimize convective heat loss. Heat input is maximized by exposing the maximum
surface area to the sun, while convective heat loss is minimized by using body
parts (such as the spread wings) as baffles to retard air movement around the
body. Orienting the body parallel to the air stream (as a wingless insect might
do) would reduce the effect of convective cooling, but orienting the body
perpendicular to the sun’s rays to facilitate heating should take precedence,
because no heat loss can be minimized until heat is first gained. Grasshoppers,
beetles, and flies use these basking methods. For some dragonflies and
butterflies the wings are especially important during warm-up in their role of
reducing convective cooling.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Behaviorally
distinct types of basking have been described in butterflies, although some
(tropical) butterflies do not bask at all. In one type, called “lateral
basking,” the butterfly closes its wings dorsally and then tilts to present
either the right or the left wing and body surface to the sun. The lower
portions of the wings wrap around the body and touch it, and warming the lower
wing portions in sunshine then causes heat to be conducted directly through
them and into the body.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Many
species of small-bodied butterflies, primarily pierids and some lycaenids
(which commonly fly in breezy mountain meadows) bask by opening their wings
partially in a V so that the body is directly available to the sun’s rays at
the bottom of the V. The wings then serve as convection baffles to reduce
cooling in the breezy environment. “Dorsal baskers” hug a solid substrate, such
as the ground, and pull their wings down around them. They thereby expose the
dorsal body surface to the sun while simultaneously capturing heat from the
sun- heated substrate.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">HEAT LOSS
MECHANISMS</span></b><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Insects
near the size of a honey bee (approximately 200 mg) or larger may experience
body temperatures during forced flight exercise that are potentially lethal to
them. Alternately,</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">metabolic
heating may inhibit continuous flight at relatively modest ambient thermal
conditions (of air temperature and solar radiation), unless one or more of the
following mechanisms for heat loss are activated.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Harnessing
Convection</span></b><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">The rate
of convective heat loss from a body is determined by the conductance of the
body, i.e., its intrinsic rate of heat loss (which is a function of body size,
shape, and insulation). Conductance, in turn, is a function of the wind speed
(a hot body cools more quickly in wind than in still air— meteorologists call
this the “wind-chill factor”). However, no convective heat loss is possible,
regardless of conductance, if body and ambient temperature are equal, and at
any one conductance and wind speed the amount of heat loss is directly
proportional to the temperature difference between the body and the ambient
surroundings.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Small
insects that are endothermic in flight are sufficiently air-cooled such that
they almost never reach the potentially dangerous high-temperature ceiling of
near 45°C that is common to most animal tissues at normal atmospheric
pressures. These small insects thus have no need of a specialized cooling
system: they lose sufficient heat passively. Theoretically, larger insects
could cool themselves by increasing flight speed and thus increasing convective
heat loss, but flying faster would generally increase metabolic heat
production, which would cancel out the increased heat loss, unless the
internally generated heat is redistributed.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Heat
Radiators</span></b><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">A radiator
is a device that increases the surface area of a body or object so that more
heat can be transmitted to the surrounding environment by convection. In some
radiators, a fluid with a high heat capacity (like water, blood, or other
liquid) circulates by means of a pump and transfers heat from its source to the
radiator site for the heat loss. That is how a car engine is cooled.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Radiators
are utilized by many large insects from the very diverse orders Lepidoptera,
Odonata, Dipera, and Hymenoptera. The animals have a fluid-transfer cooling
mechanism that dissipates heat through an abdominal radiator, while small
members of the same groups that are not strong or continuous flyers lack the
heat-transfer response. When we humans exercise in the heat, blood is pumped to
the skin or extremities to facilitate heat loss, but this is done at the
expense of pumping blood and oxygen to the muscles instead. Therefore, work
capacity is compromised. Insects, on the other hand, do not need to compromise
aerobic work capacity at higher air temperatures because of thermoregulation.
In insects, the total separation of respiratory and heat-transfer functions
makes it possible for them to continue working, even when the fluid flow is
interrupted.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">The
“radiator tube” that conducts the hemolymph to the abdominal heat radiator in
insects also serves as a pump,</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">which
operates by peristaltic contractions along its entire length. Although sphinx
moths in whom surgery has rendered this “heart” inoperative (by tying it shut)
can still fly until reaching near-lethal thoracic temperatures, removal of
their insulating layer of thoracic scales makes continuous flight again
possible.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Evaporative
Cooling</span></b><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">One of the
extraordinary examples of an evaporative cooling mechanism specifically for
thermoregulation is that found in the workers of honey bees, <i>Apis mellijera,</i>
and yellowjackets, <i>Vespula</i> spp. These insects use the head as a
radiator, but they do so with a difference. Nectar-gathering honey bees
normally fly with flight-motor temperatures near 15°C above air temperature.
They are capable of the astounding feat of flying even at ambient temperatures
near 45°C while maintaining the thorax at the same or only slightly lower
temperature. They do so by regurgitating nectar from the honeycrop, and while
the nectar is held on the mouthparts and the head, water evaporates from it.
Because of the physical contact between the head and the thorax,
thermoregulation of one effectively results in thermoregulation of the other.
Thus, the head is cooled by evaporation of water until there is a large temperature
difference between the head and the metabolically heated thorax, at which point
heat from the thorax follows the temperature gradient and is transmitted to the
head. Head temperature is actively regulated, with thoracic temperature passively
following, because artificial heating of the thorax alone does not result in
the heat-dissipation response so long as head temperature remains low. However,
artificial heating of the head (as with a narrow beam of light from a heat
lamp) almost immediately results in nectar regurgitation and evaporative
cooling, even while thoracic temperature is still (momentarily) low.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Some
insects cool evaporatively from the back. In the hot Australian deserts, the
larvae of the sawfly <i>Perga dorsalis,</i> in response to solar heat stress,
first raise their abdomen to the sun to shade the body and to increase
convective heat loss. In an emergency, when this response is insufficient, they
also emit rectal fluid and spread it over their ventral surface to cool
themselves evaporatively.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<i><span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Diceroprocta
apache</span></i><span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";"> of the Sonoran desert of the southwestern
United States employs a third evaporative cooling mechanism, this one analogous
to sweating. These cicadas are plant-sap feeders, and despite living in a dry
environment, they have access to a large fluid supply by inserting their
sucking mouthparts into the xylem of deep-rooted shrubs, such as mesquite. They
thus indirectly tap water from deep underground stores. Cicadas sing when
ambient temperatures in the shade reach 40°C, and the repetitive contractions
of their tymbal muscles result in internal heat production that adds to the
already considerable external heat load.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; line-height: 115%; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Body temperature during this exercise in
the heat is reduced to tolerable levels by evaporative cooling from fluid shed through
large pores distributed over their dorsal body surfaces. The release of this
fluid, and the consequent evaporative cooling, occurs only in response to very
high body temperature. Most insects, especially those of desert environments,
are instead highly resistant to water loss when alive, and upon death, there
results an immediate <i>increase</i> in water loss as the spiracles are no
longer actively maintained shut. Killing of the cicada, in contrast,
immediately stops the sweating response, therefore showing that it is under
metabolic control. The cooling response is mediated, ironically enough, by
aspirin-like substances produced in their bodies in response to heat stress.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">MORPHOLOGY
AND THERMOREGULATION</span></b><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Aside from
physiology, various aspects of insects’ morphology come into play in their
thermoregulating responses.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Insulation</span></b><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Many
hot-blooded insects that regulate their body temperature have, like their
endothermic vertebrate counterparts, bodies wholly or at least partially
covered with insulation. One type of insulation is derived from air sacs.
Insects already have air sacs used for breathing, and still air is, next to a
vacuum, the best possible insulator. Many insects of various orders have air
sacs between the thorax and the abdomen that greatly retard the leakage of heat
into the abdomen. But large-bodied dragonflies have gone one step further:
their air sacs surround the thoracic flight motor. The other two types of
insulation are derived from exterior cuticular structures.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Lepidopterans
are covered with a layer of thin overlapping scales, which are especially
noticeable in coloring the wings. Rather than remaining flat and colorful for
visual signaling as in butterflies, they have become long and thin to form a
thick insulating body (thoracic) pile or fur coat in many moths. This coating
of pile is so effective as insulation it more than halves the rate of heat
loss, or doubles the temperature excess, hence permitting flight at much lower
air temperatures. Endothermic insects with pile now fly in many northern areas
and at times of the year at which they would otherwise be excluded. Conversely,
insects from tropical environments have no or only sparse pile covering.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">A covering
of setae, small hair-like projections from the cuticle, is the third source of
insect insulation. Setae have various functions and numerous independent
evolutionary origins. Within the Hymenoptera, only the northernmost large bees,
the bumble bees, have a heavily insulated flight motor. However, even honey
bees have a layer of short insulating pile on the thorax, which aids them on
cool mornings and at high elevations. Bees inhabiting the tropics and hot
deserts do not have a covering of pile dense enough to provide appreciable
insulation. But even tropical bees cannot get along totally without setae,
because they use these projections to trap pollen from flowers. Some wasps, in
contrast, live in the same northern areas that bumble bees do,</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">but they
do not rely on pollen for protein. Instead, many are predators on fast-flying
insects, and they are glabrous. Perhaps an advantage of fuel economy in flight,
or perhaps the necessity for fast flight, has assumed more importance than
drag-inducing insulation for thermoregulatory control.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Color</span></b><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">In a few
instances, an insect’s color has a functional significance in thermal balance
during basking. For example, lateral- basking sulphur butterflies <i>(Colias</i>
spp., usually yellow or white) found in cool environments (such as mountaintops
or high latitudes) or seasons (early spring) tend to have dark wing undersides.
These darker individuals are able to heat up the thorax slightly faster than
lighter congeners, which buys them additional flight time when basking is
needed to prepare for flight.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Although
color can have a slight thermal advantage, it is more often subservient to
other needs, such as the need to evade predators. Not surprisingly, insects
that inhabit open ground often match their background in color and thus are
highly camouflaged.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<a href="http://www.blogger.com/null" name="bookmark3"><b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Stilts and Parasols</span></b></a><span style="mso-bookmark: bookmark3;"></span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">A beetle
walking on hot desert sand might experience temperatures that could kill it in
a minute or less. Just a few millimeters above the ground, however, the hot,
ground- hugging air layer is disrupted and mixed with cooler air from above. If
we were shrunk to Lilliputian size and forced to live where a few millimeters’
difference in elevation could mean the difference between life and death, we
would find some way to lift ourselves above the searing heat. Numerous ground-
dwelling beetles living on hot sands do just that. Tiger beetles (Cicindelidae)
begin to stand tall when sand temperatures exceed 40°C. Aside from extending
their jointed legs to stand taller, some beetles, like <i>Stenocara phalangium</i>
(Tenebrionidae) from the Namib Desert of southern Africa, have evolved very
long stilt-like legs that allow them to avoid overheating by both avoiding the
heat at ground level and losing some of the solar heat by convection through
fast running.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Another
option is to use one body part to shade another. For example, some beetles
reduce their absorption of external heat from direct solar radiation by having
an air space beneath the elytra that insulates the abdomen from direct solar
radiation.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<a href="http://www.blogger.com/null" name="bookmark4"><b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Countercurrent and Alternating-Current Heat Exchanges</span></b></a><span style="mso-bookmark: bookmark4;"></span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">At low air
temperatures when the abdomen is cool, the flight motor could cool
precipitously if the hemolymph carried heat away from the thorax to be
dissipated from the abdomen. Two mechanisms, however, normally prevent this
potential problem of thoracic cooling. The first is a temporary reduction or
elimination of the circulation: to retard heat loss.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Another
mechanism, one more subtle than cardiac arrest, helps some insects prevent heat
leakage from thorax to abdomen. Proof of that is seen in honey bee workers and
Cuculliinae winter moths, which never show appreciable increases in abdominal
temperature, even as the flight motor stays hot. An examination of their
circulatory anatomy explains the mystery: they harness countercurrent heat
transfer.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">A
countercurrent implies two separate currents flowing next to each other but in
opposite directions, as through the petiole between thorax and abdomen in
insects. If the fluid in one current is of a higher temperature than that of
the other, then heat (which is not confined by the vessel walls) will passively
flow “downhill,” from high to low temperature, across these walls. Thus, if the
hot blood leaving the thorax flows around the vessel in close proximity to cool
blood entering it from the abdomen, as in most bees, then heat exchange is
inevitable. At least some of the heat from the thorax will be recycled back
into the thorax because the incoming blood is heated by the outgoing blood. In
honey bees and winter moths, countercurrent heat exchange is greatly enhanced
by prolonging the area for that potential heat exchange to occur, as the aorta
in the petiole is lengthened and (in honey bees) convoluted into loops.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Bumble
bees and northern vespine wasps have a very much different and seemingly less
efficient countercurrent heat exchange circulatory anatomy than honey bees and
winter moths (Fig. 1). This situation may seem counterintuitive because they
live in cold climates, some species even inhabiting the High Arctic. They might
thus be expected to have even better countercurrent heat exchangers than honey
bees, which are of temperate and tropical origin. Instead of</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 8.0pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Aorta</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 8.0pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Insulation</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 8.0pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">■—Air sacs —</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 8.0pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Ventral diaphragm</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 8.0pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">FIGURE 1 </span><span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 8.0pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Anatomy of a bumble bee <i>(Bombus)</i> relevant to thermoregulation.
The thorax is insulated with pile that reduces the rate of convective heat
loss. The ventor of the abdomen is lightly insulated or uninsulated when the
bee presses her abdomen onto brood to be heated. Hemolymph (blood) is pumped
anteriorly by the heart, from the abdomen into the thorax. When dissipating
heat from the working muscles in the thorax, the blood enters the aorta from the
heart in pulses. Each pulse of cool blood from the abdominal heart into the
thoracic aorta alternates with a pulse of warm blood entering the abdomen to
the thermal window. In this way, countercurrent heat flow (into blood returning
to the thorax) is minimized and heat flow (into the abdomen) is maximized.
[Reproduced, by permission of Oxford University Press, from B. Heinrich,
(1976),/. <i>Exp. Biol.</i> 64, 561-585.]</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">having
more loops for countercurrent heat exchange, they have none! Nevertheless,
their anatomy can also be understood in terms of thermal strategy, but as it
relates to their social system.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Bumble bee
and wasp queens start their colonies very early in the spring; each new queen
attempts this task alone, as an individual. To this individual bee or wasp,
time is of the essence, for she must complete the whole colony cycle within a
single growing season. A queens first priority, then, is to rear a group of
helpers. Temperatures when and where she builds her nest may be near 0°C, and
if the brood were left at that temperature it might take years for them to
develop to adults—provided they could withstand the freezing temperature. Even
in the High Arctic, however, the queens of <i>Bombus polaris</i> can produce a
batch of workers in about 2 weeks, as can other bumble bees and <i>Vespula</i>
wasps. Both bees and wasps accomplish these feats by incubating the brood from
the egg to the pupal stage. The queens perch upon their brood clump—consisting
of eggs, larvae, and/or pupae—and they press their abdomen upon the brood, much
as a hen incubates her eggs with her belly. Only the abdomen provides a smooth
surface for contact, but only the thorax produces heat by way of intense
shivering by the flight muscles. No incubation, and hence social life, would be
possible for these insects in a cold environment if, like honey bees, they were
incapable of transferring heat from the source of its production into the
abdomen that provides the smooth tight contact with the brood.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">The bumble
bees aorta is long enough to permit moderate heat exchange and hence retention
of heat in the thorax, but it is short and straight enough so that a
physiological mechanism can be activated that shunts the fluid and heat
through, effectively eliminating countercurrent heat exchange.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Countercurrent
heat exchangers in vertebrate animals can be bypassed by rerouting the blood
into an alternate (generally external) channel. That is why our own veins seem
to pop out when we are active in the heat. Such rerouting of the blood from
internal to external channels is not possible, however, in insects with open
circulatory systems lacking veins and capillaries. Instead, in bumble bees
there is a physiological solution for heat loss in the presence of a
countercurrent heat exchange anatomy that serves the same purpose as an
alternate blood channel. In the bumble bee, this consists of an <i>alternating-current</i>
flow of blood. To shunt heat past the heat exchanger and into the abdomen, the
bee lifts a small valve that allows a pulse of warm blood to enter the abdomen,
and in the fraction of a second after the warm blood enters the abdomen, she
then squirts a bolus of cool blood into the thorax. And so it goes back and
forth, hot and cold pulses of hemolymph passing alternately through the heat
exchange area in the bee s waist. The essential point is that although the
blood is not rerouted into a different channel, it is instead temporarily
“chopped” into alternating pulses in the same channels. This is the opposite of
countercurrent flow because instead of recovering heat from the thorax, the
system acts to remove it, in this case into the abdomen.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; line-height: 115%; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">The pumping of hemolymph by the heart
and the ventral diaphragm is also aided by in—out pumping movements of the whole
abdomen, which otherwise function only for moving gas in and out of the thorax;
the in—out telescoping movements of the abdomen are synchronous with the heart
beats and the ventral diaphragm beats, and they cause pressure changes that
facilitate hemolymph flow in precise alternating currents.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">THERMAL
ARMS RACES Against Predators</span></b><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">On a
summer day in the Sahara Desert in Algeria, as the sun rises and begins to heat
the sands that have been cold at night, an abundance of insect life is forced
to retreat to cool underground refuge. Those unfortunate ones caught out in
the heat become disoriented and, moving frantically, they heat up even more,
then they die. The sun keeps rising, and sand temperatures begin to exceed
46°C. The desert lizards, <i>Accanthodactylus dumerili,</i> continue to hunt the
incapacitated prey and any ants they can find. But they now dash quickly across
the sand, and when they stop and stand, they alternately lift their feet to
prevent burning them. Meanwhile, long-legged silver ants, <i>Cataglyphis
bombycina,</i> avoid the lizards by remaining in their burrows under the sand.
However, they are poised to leave, waiting for the sand temperatures to heat up
even more, until it reaches about 60°C, when the temperature of the air at ant
height is about 46.5°C. Temperature “testers” among them lurk at the nest
entrance. At the right moment, they signal the time to come out by releasing
pheromones from their mandibular secretions. The rest of the colony then rushes
out into the field to forage safely, until they too must retire back to their
underground shelters—when they experience air temperatures of 53.6°C, which is
just a fraction of a degree below their thermal death point.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">In the
southwestern deserts of the United States near Phoenix, Arizona, the desert or
Apache cicada, <i>D. apache,</i> also engages in a thermal arms race against
vertebrate predators. These cicadas are active at the hottest time of the year,
and even then they wait until the high midday temperatures of 44°C (in the
shade) near noon to be most active, when the cicada- killing wasps and birds
are forced to retire from the heat.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">In the
deserts of southern California, the grasshopper <i>Trimerotropis pallidipennis</i>
endures heat rather than regulating heat loss like the sweating cicada. By
blending in with the background of the desert floor, it hides to escape bird
and lizard predators. Normally grasshoppers that inhabit the ground stilt high
above that substrate when it becomes heated to very high temperatures in
sunshine. But to remain camouflaged it is imperative for <i>T. pallidipennis</i>
to crouch down onto the searing hot ground. When that ground heats to near 60°C
in sunshine, the duration of time that a grasshopper can remain hidden is
limited by how high a body temperature it can tolerate. <i>T. pallidipennis</i>
has evolved to tolerate the extraordinary high body temperature of 50°C and can
thus escape into the sanctuary of sunlight, where a predator such as a lizard
or bird cannot hunt.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">It is
probably rare that insects escape predators by seeking out low temperatures.
Possibly the best candidates are the Cuculli- inae, a subfamily of the
generally endothermic Noctuidae or owlet moths. The Cuculliinae are a northern
circumpolar group of moths, and in northern New England they may fly during any
month of the winter when temperatures reach 0—10°C and when most of their bat
and bird predators have left. During flight, cuculliinines have flight-motor
temperatures near 30—35°C, as do other moths of their size and wing loading.
Unlike all other moths, however, the cuculliinines can begin to shiver at the
extraordinarily low muscle temperature of 0°C, and they continue shivering to
warm up all the way to 35°C.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">The giant
hornets, <i>Vespa mandarinia,</i> attack honey bee colonies. During a typical
giant hornet attack, a lone hornet forager first captures bees at the periphery
of the bees’ nest. After several successful foraging trips to the beehive, the
hornet deposits a marking pheromone at the hive entrance from the van der Vecht
gland at the tip of the abdomen. This pheromone attracts other hornets from the
home nest, and then the slaughter phase of the hornet attack begins: 30,000
bees can be killed in 3 h by a group of 30 to 40 hornets. Subsequently the
hornets may occupy the hive itself, and then they carry off the bees’ larvae
and pupae to feed to their own young.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">The above
happens when hornets attack colonies of the introduced European honey bee, <i>A.
melUfera,</i> but the Japanese honey bee, <i>A. cerana,</i> has evolved an
effective counterstrategy to the hornets’ mass invasion. With the latter,
those unfortunate hornets that are recruited by the pheromone and then try to
enter the hive are met and killed by heat as hundreds of bees envelop each wasp
into a tight ball. The interior of these bee balls quickly rises to 47°C,
killing the hornet but not the bees, whose upper lethal temperature is 48 to
50°C.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Against
Competitors</span></b><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Contest
competition or fighting over food is rare in insects, but at least two species
of African dung beetles, <i>Scarabaeus laevistriatus</i> and <i>Kheper
nigroaeneus,</i> engage in combat over dung balls that they make to feed on
and/or to serve as sexual attractants. An elevated thoracic temperature plays a
crucial role in these contests on the ground. The more a beetle shivers to keep
warm (with its flight muscles), the higher the temperature of the leg muscles
adjacent to the flight muscles in the thorax and the faster its legs can move
and construct the dung into balls and roll it away. Endothermy thus aids in the
scramble competition for food, and it reduces the duration of exposure to
predators. Additionally, hot beetles have the edge in contest competitions over
dung balls made by other beetles; in fights over dung balls, hot beetles almost
invariably defeat cooler ones, often despite a large size disadvantage.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Mate
Competition</span></b><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; line-height: 115%; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">For large insects, endothermic heat
production is a requisite for flight, and it is during flight that other
activities, including foraging, oviposition, and predator escape, as opportunity
and necessity dictate, may occur. Hence, to find a direct effect of body
temperature on mating success specifically, one must examine a mating behavior
that is not already tightly linked with some other temperature-dependent
activity. Singing in some species is a good candidate. Singing is one activity
that serves only for mate attraction, and in katydids and cidadas only males
sing and the females remain silent. The vigor of this singing activity is
associated with and dependent on thermoregulation. Katydids, <i>Neoconocephalus
robustus,</i> warm up for their ear-shattering mating concerts by shivering,
bringing flight-muscle temperatures above 30°C. Males of the Malaysian green
bush cricket, <i>Hexacentrus unicolor,</i> sing from dusk until well into the
night, and before they sing, they prepare themselves by shivering to achieve
thoracic temperatures near 37°C. At thoracic temperatures of 37 to 38°C, the
males are able to achieve the extraordinarily fast wing movements of up to about
400 vibrations per second.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; line-height: 115%; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">The
dragonfly <i>Libellula pulchella</i> demonstrates both the importance of body
temperature for mating success and the trade-offs required for maximizing power
output as an insect matures. The young, nonreproductive adults of this species
are sit-and-wait predators that typically fly with relatively low thoracic
temperature. Their flight-muscle performance does not peak at any one
temperature; instead, performance is uniformly spread over a wide range of low
thoracic temperatures. In contrast, sexually mature males engage in nearly
continuous flight in intense territorial contests. At such times, they generate
a very high thoracic temperature, and they regulate that thoracic temperature
precisely and within only 2.5°C from their upper lethal temperature. Thus,
muscle performance of the sexually mature males is narrowly specialized
relative to that of young adults that do not engage in strenuous battle.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">SOCIAL
THERMOREGULATION</span></b><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Many of
the social insects regulate the temperature of their nests in coordinated
behavioral and physiological responses involving the adult nest inhabitants.
Nest temperature regulation functions primarily to maintain activity and to
keep the otherwise thermally labile larvae at the proper temperature for rapid
growth. Thermoregulation allows social insects to rapidly build up large nest
populations and to inhabit environments where they could not otherwise exist.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Nest Site</span></b><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">One of the
first requirements for effective nest temperature regulation is the choice of
an appropriate nest site. Typically, northern ants nest in the open, often
under solar-heated rocks, or they make solar-heated mounds; many termites also
nest to maximize exposure to solar radiation. Honey bees, that live in northern
temperate climates require enclosed nest sites such as tree cavities, whereas a
variety of other more tropical bees have open and exposed nests.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Nest
Construction</span></b><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Northern
vespine wasps enclose their nests in multiple layers of paper that insulate the
nest contents. Some termites and ants construct nests so located and
constructed as to maximize solar heating in the morning and evening and to
minimize overheating at noon. Nests may be constructed so that air circulation
and heat transfer are enhanced for thermoregulation.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<b><span lang="EN-US" style="color: #b25412; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Behavior
and Physiology</span></b><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; text-align: justify;">
<span lang="EN-US" style="color: #231f20; font-family: "Garamond","serif"; font-size: 10.5pt; mso-ansi-language: EN-US; mso-bidi-font-family: Garamond; mso-fareast-font-family: "Times New Roman";">Ants
regulate the temperature of their brood by carrying it to those parts of the
nest with suitable temperatures. Both honey bees and vespine wasps regulate the
temperature of the nest, especially near the brood. They fan to circulate air
and carry off heat when nest overheating is imminent, and if temperatures
continue to increase they carry in water and sprinkle it on the combs for
evaporative cooling results. At low temperatures, such as during winter and in
swarm clusters outside the hive, the bees crowd together tightly as air
temperatures drop, thereby trapping heat inside. As air temperatures rise, the
bees on the cluster start to disperse, the cluster loosens, and heat from the
interior is released. In hives containing both honeycomb and comb with brood,
the bees preferentially cluster around the brood. Brood temperature is
maintained near 36°C in hives that may be subjected to air temperatures as low
as —50°C and as high as 50°C, provided the bees have access to honey as an
energy source for heat production in the cold and to water for evaporative
cooling in the heat.</span><span lang="EN-US" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-IN;"></span></div>
</div>
DR. LAXMIKANT B. DAMAhttp://www.blogger.com/profile/13198225293462944168noreply@blogger.com4tag:blogger.com,1999:blog-4764725322678313110.post-64213749178496647042013-07-10T04:23:00.002-07:002013-07-10T04:26:27.678-07:00<div dir="ltr" style="text-align: left;" trbidi="on">
<h2 style="text-align: center;">
Temperature, Effect on devlopment and growth of Insect</h2>
<h2 style="text-align: center;">
(effect of temperature on development of insect )</h2>
<h2 style="text-align: left;">
</h2>
The body temperature of insects, as in other ectothermic organisms, is linked to changes in the ambient temperature.<br />
Temperature fluctuations are small in environments such as the tropical rainforest, caves, and some aquatic habitats. In most habitats, however, the seasonal and diurnal temperature oscillations are considerable. For example, insect body temperature can change abrupdy by 10°C or more when exposure to direct sunlight is followed by the shade of a cloud. The way of life with fluctuating body temperatures is called heterothermy; this is in contrast to the homeothermy of endothermic organisms, such as birds and mammals, which regulate their body temperature, partly by generating endogenous heat.<br />
<br />
DEVELOPMENTAL PARAMETERS<br />
<br />
Every organism is adapted to a set temperature range. A general preference for high temperatures is referred to as thermophily, and the inclination to low temperatures is psychrophily. Insects living in warm climates or parasitizing warm-blooded animals are thermophilic, whereas those dwelling in soil are usually psychrophilic. Temperature preferences may change during development; for example, aquatic insects inhabit cold mountain streams during their immature stages but fly in warm air as adults. Temperature fluctuations within the species-specific physiological range determine the rate of development and often exert other physiological effects.<br />
<br />
Development and reproduction occur at physiological temperatures that are delimited by an upper and a lower developmental threshold (UDT and LDT, respectively). Within this range, there is an optimal temperature for rapid development. The dependence on temperature can be expressed as a metabolic rate or as a developmental rate. The metabolic rate (MR) reflects the velocity of the energy-supplying biochemical processes and can be measured as oxygen consumption, carbon dioxide production, or heat generation. Many enzymatic reactions and the total body metabolism increase exponentially over a broader temperature range than is the span of physiological temperatures. Metabolic increase is usually two- to threefold with temperature elevation by 10°C and can be expressed by MR = , where a and k are constants and T is temperature.<br />
<br />
Metabolic rate determines the developmental rate (DR), which is a reciprocal value of the developmental time (DT), DR = 1/DT. Measuring developmental times, such as duration of larval development, length of the reproductive period, or expanse of the entire life cycle, requires maintenance of defined conditions (notably temperature and nutrition). This is difficult to do for long periods of time and this is why DT and DR values are usually established for individual developmental stages and then recalculated for the entire life cycle. Circadian rhythmicity of some processes, for example, the synchrony of hatching or adult emergence at a certain time of day, complicates DT assessments.<br />
<br />
In contrast to the exponential rise of the metabolic rate, the increase in DR within the physiological temperature range is linear. When a series of temperature and corresponding DR values is plotted in a graph, a straight line so obtained crossed the x axis at the theoretical LDT point. Close to this point, the relationship between developmental rate and temperature ceases to be linear, and the straight line is bent into a sigmoidal curve. Actual LDT is therefore somewhat lower then predicted. At the upper temperature range, the DR slows down before it reaches a maximum at the optimal temperature. After the maximum, DR sharply drops and at UDT the development is discontinued.<br />
<br />
Developmental time depends on the effective temperature, i.e., temperature value above LDT (actual temperature T minus LDT). The constant product of effective temperature and developmental time is called the sum of effective temperatures (SET) and represents the heat required for the completion of a particular developmental stage. SET is conveniently expressed as the number of degree days. For example, a SET value of 100 degree days means that development at 5°C above LDT lasts 20 days and at 10°C above LDT 10 days. When the insects develop at fluctuating temperatures, the average temperature above LDT and the length of time when the temperature surpasses LDT are considered for each day, and the number of degree days established in this way is summed. Developmental stage is completed when the summation reaches the SET value.<br />
<br />
A temporal drop in temperature below LDT is associated with developmental block and is counted as 0. Usually, there is no “negative developmental rate” at temperatures below LDT, i.e., no delay of development is observed after transfer to an effective temperature. Natural temperature fluctuations, however, may have a signaling effect and influence the SET value in some species, and this possibility must be checked experimentally.<br />
<br />
The LDT and SET values are species-specific population characteristics. The LDT values are similar for all developmental stages of a given species, even when they develop in diverse seasons and experience disparate temperature fluctuations. The stability of LDT is manifested as developmental thermal isometry, i.e., the percentage of time spent in a particular stage at any constant physiological temperature is a stable fraction of the entire developmental time. The LDT and SET values established in the laboratory enable prediction of the course of development in the field. Control of many insect pests in agriculture and forestry largely relies on such predictions. For example, on the basis of the LDT and SET data for the codling moth (Cydia pomonella) we can predict, on the basis of daily temperature measurements in an orchard, the time of the first egg deposition and time insecticide sprays accordingly.<br />
<br />
Both LDT and, especially, SET may vary between geographical populations because of adjustments to local climatic conditions. Insects that have spread to temperate zones from the tropical regions often maintain a high LDT and can reproduce and develop only in the hot season, spending most of the year in a state of dormancy. The survival in cold is made possible by increased cold hardiness, a parameter that seems to be more plastic than LDT.<br />
DEVELOPMENTAL ARRESTS<br />
<br />
Most insects must overcome long periods of adverse conditions when food is wanting and temperature remains outside the physiological limits. Insects cease development and reproduction but, if the temperature does not reach lethal extremes, they remain capable of resuming these processes as soon as the conditions become favorable. The state of easily reversible, directly temperature-dependent developmental arrest is known as quiescence. It is typical of insects adapted to relatively short periods of unfavorable, nonlethal circumstances, and it is usually associated with temperature acclimation.<br />
<br />
Insects that will be exposed to severely hostile conditions that can last for many months enter a programmed developmental arrest, diapause. Diapause occurs in anticipation of a season in which the insect could not survive in the active state. It is induced by environmental signals acting before the adverse conditions set it, sometimes on a much earlier developmental stage and exceptionally on the parental generation.<br />
<br />
Seasonal changes in the environment are specific for each latitude, altitude, and habitat, but always correlate with changes in the photoperiod, i.e., the length of day versus the length of night. Photoperiodic changes therefore provide ideal signal for the advent of unsuitable conditions. However, temperature can shift the diapause-inducing photoperiod response over a broad range. For example, 50% of caterpillars of Acronycta rumicis are induced to enter pupal diapause at a daylength of 19 h at 15°C, but at 16 h at 25°C. Low temperature normally enhances the effect of short photoperiod and high temperature enhances the effect of long photoperiod. Daily fluctuations of temperature, the thermoperiod, can induce diapause in a few species kept in constant darkness. On the other hand, high temperature can abolish the diapause-inducing effect of a short photoperiod. For most insects, the diapause is facultative and there is a variation in the critical photoperiod/thermoperiod at which each individual enters diapause.<br />
<br />
Once induced, diapause is not terminated immediately after the diapause-inducing conditions disappear. A certain time must elapse, during which neurohormonal regulations return to the pattern supporting development and reproduction. The mechanisms controlling diapause termination are not known. The length of time in diapause depends on its “depth” and on environmental conditions, especially temperature, to which the diapausing insects are exposed. In the overwintering insects, diapause is often shortest at temperatures around 5°C (Fig. 1) and the photoperiod is irrelevant. Due to exposure to low temperatures in late fall, the overwintering insects terminate diapause in early winter, and the resumption of their development or reproduction is then halted only by a direct effect of low temperature: diapause turns into quiescence.<br />
<br />
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjagvLaamyxtZCSzBRTITmPaA8lxM5GWMuLLYiIkqz8Ny0naLEZqEsVejPm0glkY86P3XzfxneeU-G8F3LlDg4Wx4AXf-QhOUJ8_zOBQVzAJX16mfU_YWlvx8WfhKAdZ6iAgf8G5MJxhdM/s1600/1+-+0003.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="348" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjagvLaamyxtZCSzBRTITmPaA8lxM5GWMuLLYiIkqz8Ny0naLEZqEsVejPm0glkY86P3XzfxneeU-G8F3LlDg4Wx4AXf-QhOUJ8_zOBQVzAJX16mfU_YWlvx8WfhKAdZ6iAgf8G5MJxhdM/s400/1+-+0003.jpg" width="400" /></a></div>
<br />
ALTERNATIVE DEVELOPMENTAL PATHWAYS<br />
<br />
In certain insects, temperatures within the physiological range affect the course of non-diapause development. For example,<br />
<br />
larvae of the yellow mealworm, Tenebrio molitor, develop in 11-15 instars at 25°C and in 15-23 instars at 30°C. Less dramatic changes in the number of molts and the growth rate were noted in a number of insects. Abnormal temperatures can also dissociate the onset of metamorphosis from the body size at which it normally occurs. In the wax moth, Galleria mellonella, placing newly ecdysed larvae of the last or penultimate instar on melting ice induces an additional larval molt. To cause such anomalies, the temperature must alter the secretion of hormones that control specific developmental events.<br />
<br />
Some insect species occur in more than one form and their alternation depends on temperature. For instance, development of young caterpillars of Colias eurytheme at 18°C leads to mainly yellow, and development at 27—32°C to orange, butterflies. The spring and summer forms of some other butterflies are well known examples of seasonal dimorphism in which one form is linked to diapause.<br />
<br />
LETHALITY AT EXTREME TEMPERATURES<br />
<br />
A general response of insects to temperatures just below their LDT or above their UDT is the cessation of development and reproduction while the insects remain active and feed. The larvae may slowly grow and the adults accumulate reserves and to some extent undergo gonadal maturation. These processes are terminated at more extreme temperatures when the insects begin to die.<br />
<br />
During cooling, the metabolic rate and motility gradually decrease. At a certain temperature, the neural and muscular activities are impaired and the insect lapses into cold stupor. The metabolic rate of such immobile insects continues to decline with decreasing temperature. The stupor point is as high as 12°C in some tropical insects and the honey bees, around 5°C in many temperate species, near 0°C in most overwintering insects, and below the freezing point in species living in very cold areas.<br />
The nature of chill injuries is little understood. Desiccation and nutrient depletion during the cold-induced starvation are certainly incompatible with long-term survival, but death usually occurs earlier and is probably the result of damaging effects at cellular level. The loss of cell membrane fluidity, imperfect protein functions (enzymatic activities, transport, signaling, etc.), and the resulting asynchrony of the life-supporting processes cause metabolic disorders. For example, the ion pumps in the cell membrane become inefficient and sodium concentration in cytoplasm increases, while the potassium ions flow out into the hemolymph.<br />
<br />
The upper temperature extremes are also lethal. Gradual warming past UDT, which is for many species around 35°C but is never sharply delimited, increases the metabolic rate, loss of water, and motility. At a certain temperatures, usually around 40°C, the water loss, and thereby the evaporative body cooling, increases sharply. The spiracles are wide open and the melting of cuticular lipids permits evaporation through the body surface. After some time at such a high temperature, the losses of water and nutrients lead to exhaustion, manifested as a rapid decrease of motility and a drop of transpiration. If this state is brief, it can be reversed. The temperature at which it occurs is the upper lethal threshold. A gradual temperature increase to this threshold may cause heat stupor.<br />
<br />
Survival at temperatures above the threshold is a function of temperature and length of exposure. Warming to the absolute upper lethal temperature, which is usually around 50—55°C, causes irreversible tissue damage, and even a short exposure is lethal.<br />
<br />
ACCLIMATION AND TEMPERATURE TOLERANCE<br />
<br />
The survival at extreme temperatures is improved after an acclimation. Shortening of the photoperiod in late autumn and early winter usually acts synergistically with descending temperature in triggering a seasonal cold acclimation. An exposure to low temperature alone is often insufficient for full cold acclimation and successful winter survival because some physiological adjustments (for instance down-regulation of the ice nucleators and enhancement of cryoprotectant biosynthesis) require a preceding switch to the diapause developmental mode and this is controlled by the photoperiod. In other insects, cold acclimation is associated with temperature-dependent quiescence and the photoperiod is irrelevant.<br />
<br />
Cold acclimation is a complex adjustment involving profound changes at the organismic and tissue levels. Accumulation of low-molecular-weight cryoprotective polyols and, in some insects, also synthesis of antifreeze proteins are characteristic features of cold acclimation. Other physiological changes include changes in cuticular lipids, increased fluidity of phospholipids in the cell membranes, conformation changes of some proteins, possibly production of alternative enzymes with activity optima at lower temperatures, and synthesis of heat-shock proteins. Acclimation may also encompass changes in morphology (e.g., cold-acclimated lacewings turn from green to reddish brown) and behavior (e.g., formation of cocoons with higher resistance to desiccation and ice penetration, voiding the gut to get rid of ice nucleators, and seeking dry places to prevent ice inoculation from the surroundings).<br />
<br />
The temperature at which insects freeze is relatively low even without cold acclimation. Insects contain only low amounts of nucleators needed for the ice crystal formation and are therefore capable of considerable supercooling. The nonacclimated individuals freeze at —10 to — 15°C, while those with accumulated cryoprotectants and antifreeze proteins can be supercooled to temperatures below —20°C. All cryoprotec-tive compounds disappear from the organism after a certain time. The length of this deacclimation process also depends on temperature, but details have not been examined.<br />
<br />
Changes associated with heat acclimation are litde known. Synthesis of heat-shock proteins, which were discovered in Drosophila exposed to elevated temperature, is a very general response not only to heat but also to cold and various other types of stress. Several types of heat-shock proteins are known from organisms ranging from bacteria to plants. It is believed that they are chaperones enabling or protecting functional protein conformations. Temperature or another stressing factor acts as a signal inducing their synthesis at transcriptional level. Accumulation in the cells of “unfolded” proteins is believed to be the common intracellular message triggering this transcription.<br />
<br />
<br />
<br />
<br />
<i>Ref: Frantisek Sehnal, Oldfich Nedved, and Vladimir Kost’al<br />Institute of Entomology, Academy of Sciences, Czech Republic</i></div>
DR. LAXMIKANT B. DAMAhttp://www.blogger.com/profile/13198225293462944168noreply@blogger.com0tag:blogger.com,1999:blog-4764725322678313110.post-72918715923645408802010-10-11T00:39:00.001-07:002010-10-11T00:39:30.682-07:00Role of insect in biological weaponsRole of insect in biological weapons<br />
THE ROLE OF INSECTS AS BIOLOGICAL WEAPONS <br />
The following is based on the notes for a seminar presented by R.K.D. Peterson in 1990 at the University of Nebraska . The information is from several published primary and secondary sources listed at the end of this article. <br />
WHAT IS A BIOLOGICAL WEAPON? <br />
Before discussing the role of insects in biological warfare (BW), we need to define biological warfare and just what a biological warfare agent is. The definition is from the 1972 biological weapons convention. The definition for a BW agent is fairly straightforward: <br />
"Microbial or other biological agents, or toxins whatever their origin or method of production, of types and in quantities that have no justification for prophylactic, protective or other peaceful purposes." <br />
This definition includes all living BW agents, including insects, as well as toxins produced from these agents (e.g., the botulinum toxin). <br />
INSTANCES AND ALLEGATIONS OF BW (PRE 1800) <br />
The recorded allegations and instances of BW before 1800 do not involve insects. However, it is important to discuss some of these records to understand the full spectrum of BW. <br />
600 B.C. <br />
Solon, the legislator of the Athenians, contaminated the river Pleisthnes with the plant root of helleborous to give the defenders of Kirrha violent diarrhea, which led to their defeat. <br />
ca. 200 B.C. <br />
Carthaginian general Maharbal purposely retreated from his encampment and left behind a large stock of wine that he treated with mandagora, a toxic root which produces a narcotic effect. The enemy, upon drinking the tainted wine, fell into a deep sleep and the Cartheginians returned to slay their enemy. <br />
190 B.C. <br />
Hannibal won a naval victory over king Eumenes of Pergamon by firing earthen vessels full of snakes into king Eumenes ships. <br />
There are many records throughout the ages of armies dumping dead humans and animals into wells, ponds, streams, and rivers to pollute the enemies’ water supplies. <br />
Mid 1300s<br />
Mongol tartars, sieging the port city of Feodosia (then Kaffa) on the Black Sea , finally broke the three-year siege by catapulting plague-infested cadavers over the walls of the city. <br />
The city fell from plague in 1346 and it was suspected that escaping residents of the city introduces plague into Italy , initiating the pandemic (the Black Death) that decimated the European populace between 1348 and 1350. 1763 <br />
The next recorded instance of BW was in the new world. Smallpox was strongly suspected of being used against the Indians in the French and Indian War. Sir Jeffrey Amherst, commander in chief of the British forces in the American colonies had two blankets and a handkerchief from a British smallpox hospital sent to Indian chiefs. A smallpox epidemic soon erupted. <br />
<br />
INSTANCES AND ALLEGATIONS OF BW (1800-PRESENT) <br />
<br />
The American Civil War<br />
The American Civil War marked the first instance of alleged use of an insect as a weapon of war. The Confederacy accused the Union of deliberately introducing the harlequin bug, Murgentia histrionica, into the South. <br />
Tremendous crop damage resulted in the South because of this pest. This allegation was never proven and it now appears that the harlequin bug moved on its own into the South from Mexico . However, humans may have aided in the movement of this pest. <br />
Disease relationships (microbial and insect vector) were elucidated in the early twentieth century. As soon as the mechanisms were known, military planners began to apply them as possible warfare agents. <br />
<br />
World War I<br />
None of the belligerent countries in WWI took official notice of BW. No country involved had a BW research facility and there was no BW on a large scale. <br />
BW clearly was used in sabotage operations in the war to end all wars. In 1915, German agents inoculated horses and cattle that were leaving the U.S. for allied ports with glanders and anthrax. In 1917, the Germans again were accused of spreading glanders to 4,500 donkeys on the French front, and of spreading plague on the Russian front in 1915 and 1916. <br />
As most people know, WWI was known more for the development of chemical weaponry, which was spawned by advances in the dye industry. <br />
<br />
Between the Wars<br />
17 June 1925. Geneva Protocol for the prohibition of the use in war of asphyxiating, poisonous or other gases, and of bacteriological methods of warfare. Even though biological weapons were not used on a large scale in WWI, the framers of the Geneva Protocol viewed BW as a serious emerging threat and incorporated a bacterial warfare component into the protocol. Most major countries in the world at that time ratified the treaty. <br />
The United States , however, did not ratify the treaty because of the then current isolationist movement in this country. The U.S. finally ratified this treaty in 1975, 50 years after its inception. The failure of the U.S. to ratify the treaty led the Japanese to not ratify the treaty either and to believe that BW was promising and had a future in warfare. <br />
<br />
World War II<br />
The world still is heavily influenced by the events that took place from 1939-1945, and in some respects the war finally ended less than a month ago with German reunification. <br />
World War II also was pivotal when we consider the development and use of BW. I need to look at each belligerent country's involvement because each country's involvement was unique, both axis and allied. <br />
<br />
GERMANY <br />
German involvement in BW was not nearly as advanced as Japan or the Allied Nations. It now appears that BW and BW research was not taken seriously by the German military hierarchy. Hitler, especially, viewed the emerging sciences as some sort of Jewish plot. He called the physics of Einstein, Jew physics, and felt similarly about the new biology, and the new psychology. <br />
After the successful Russian counterattacks in Russia in 1943, Hitler agreed to establish an SS BW research station at Posen. As the Russians got closer to the research station, work accelerated at the station, but no real advances were made before the Russians occupied the station in March 1945. <br />
At the Posen BW research station, the Germans performed work on the diseases plague, cholera, typhus, yellow fever, and performed experiments on the feasibility of using insects such as the Colorado potato beetle to attack Allied potato crops. The Germans were accused of dropping cardboard boxes filled with Colorado potato beetles over England from 1941-1943. The containers were never recovered but abnormalities associated with the presence of the beetles prompted Sir Maurice Hankey, head of Britain 's BW effort, to write a memo to Winston Churchill with his concerns. <br />
Also, as British invasion fears grew after the successful evacuation from Dunkirk , rumors spread that the Germans had created an omnivorous strain of grasshopper which would soon starve the British into surrender. This was a myth. However, the fact that Nazi doctors used human subjects for experiments on insect-borne diseases is no myth. Concentration camp inmates were intentionally infested with typhus-infected lice by SS doctors at Natzweiler, Dauchau, and Buchenwald . Many of these doctors and scientists were sentenced to death by the Nuremberg Tribunal after the war. <br />
<br />
GREAT BRITAIN AND THE COMMONWEALTH<br />
England had a viable BW research program since 1934. After hearing that Germany was initiating a program in 1936, a BW advisory group was established which procured antisera for human and animal diseases, and stocked insecticides and fungicides as a contingency for anti-crop attacks. <br />
In 1939, the BW advisory group assessed BW as less effective than the conventional forms of warfare, but they advised the government to begin a BW research effort. <br />
In 1940, shortly after the fall of France , a BW research unit was established within the chemical warfare research establishment at Porton Down. An experiment conducted in 1941 involved the dissemination of anthrax spores from small aircraft bombs at Gruinard Island off the northwest coast of Scotland . All the other work at Porton Down has been heavily classified and still is unavailable. The only reason the Guinard island episode is known to the general public is because the island is still uninhabitable to this day because of the presence of anthrax spores. <br />
The British effort was combined with the Canadian effort in 1942. Canada had several BW research stations throughout the country. Field testing was performed at a proving ground near Ralston , Alberta . Not much is known about what was studied there. Apparently Canada feared that North American livestock were very susceptible to Old World diseases so several were studied. As a result they studied rinderpest and a few other diseases. Also, botulinal toxins were studied and antidotes were developed. <br />
After the U.S. Entered the war, Canada and Britain shared their BW research experience with the U.S. <br />
<br />
JAPAN <br />
The only verified instance of BW during the war was the use by Japan against the Chinese, from 1937-1945. <br />
The Japanese BW program was headed by General Shiro Ishii, an army surgeon with a doctorate in bacteriology. Before Ishii began his BW efforts, he was famous for developing a portable water filtration system, capable of being transported by army regiments. <br />
Ishii strongly believed that the western powers had advanced BW programs and were prepared to use them. Again, failure of the U.S. to sign the 1925 Geneva Protocol influenced his thoughts and actions. <br />
BW research was considered too risky to study in Japan proper. Therefore, the Japanese puppet state of Manchukuo (formerly Manchuria ), under complete Japanese control since 1932, was chosen as an ideal location for the studies. <br />
Mukden POW Camp<br />
In 1936, detachment 731 was formed in the town of Harbin . The official name of the detachment was “Epidemic Prevention and Water Supply Unit of the Kwantung Army." In reality, the mission of unit 731 was to forge deadly new biological weapons for the Japanese army to be used against all possible enemies. <br />
In 1938, the success of the research and development efforts at Harbin necessitated the move of unit 731 to Pingfan, a more secure area outside of Harbin . The Pingfan complex included an insectary among its 150 buildings, where 1000 staff members worked around the clock. In total, with out-stations and personnel in the water purification units, 10,000 people were involved. <br />
Like the German scientists, human subjects were used to study these diseases. As early as 1932, people were taken from prison camps (mainly Chinese soldiers, intellectuals, and local workers). The study subjects were called Marutas, which means logs of wood. This is how they were treated. Unspeakable horrors awaited those that entered the Ro block. No subjects that entered ever left alive. <br />
The subjects were tied to posts and were forced to be bitten by plague-infested fleas. The progression of the disease was then charted very scientifically until the subjects died. If the subject did not die, he or she was usually killed, and the body dissected. Many of the human subjects were vivisected at the Ro block. A room existed there where body parts were kept and catalogued. <br />
Of course, human subjects were used on all the diseases studied at Pingfan. Gangrene was studied by exploding gangrene soaked shrapnel bombs in front of tied up Marutas. Also, frostbite was studied by gradually freezing subjects. <br />
It is estimated that 3600 people were sacrificed by the Japanese scientists in the Ro block. This was addition to possibly more than 200 American and British POW's, who were studied at the Mukden POW Camp. More than 1500 Allied soldiers may have been used in BW experimentation. The Japanese were curious to see if Anglo-Saxons and Caucasians in general responded differently to the treatments than the Chinese subjects. <br />
The Pingfan facility was able to produce 300 kilograms of viable plague germs every month, Yersinia pestis. The facility also produced cholera, typhoid, paratyphoid, dysentery, and anthrax. <br />
Ishii believed quite strongly that plague was a promising weapon of war and the insect vector was needed for delivery to the enemy. Therefore, a four-story granary was built which housed rats used as the plague reservoir. At production height in 1945, 4500 flea breeding machines were set up to produce 100 million fleas every few days. It is estimated that 3 million rats may have been used. <br />
Bombs made primarily of clay were developed for dissemination of plague-infested fleas. Also, saboteur initiation of plague via distribution of rats with plague was studied. Plans were designed for the Japanese balloon bomb to carry pathogens to America . The balloon bombs were used to attempt to ignite forest fires in the Pacific Northwest (albeit with unsatisfactory results). <br />
The actual use of bioweapons distinguished Japan from the other belligerents. Several attacks were launched against China from 1939-45. Plague-infested fleas were disseminated directly out of aircraft or via specialized bombs. In 1944, an assault team was assembled to sprinkle plague-infested fleas around the Saipan airfield, which the Americans held. The ship carrying the assault team, however, was sunk by an American submarine and the mission was never completed. <br />
By war's end, Unit 731 was preparing for a major war with Russia. The enormous breeding program was interrupted when Russia invaded Manchuria on August of 1945. The remaining human subjects were slaughtered by the fleeing Japanese guards and Pingfan was abandoned with most of the complex intentionally set on fire to destroy particularly damaging information. A plague epidemic in the Harbin and Pingfan area occurred almost immediately after the abandonment of Pingfan. It is strongly suspected that escaped rats were responsible. <br />
After the U.S. occupation of Japan, Russia began to begin making protests that the U.S. government knowingly was protecting Japanese BW specialists, and failing to bring them to justice. At the same time, the Truman administration sent a team of bacteriologists to investigate the Japanese BW program during the war. <br />
It now appears that General Douglas Macarthur, who was in charge of the occupation of Japan after the war, and his intelligence staff deliberately withheld contacts and information from the Washington scientists. These U.S. scientists found out, after they granted immunity from prosecution to the Japanese scientists in exchange for their bw knowledge, that the Japanese scientists experimented on human subjects, and specifically American POWs. Immunity would not have been granted had the scientists known this. It appears, however, that Macarthur's intelligence staff knew this, but was so desperate for the Japanese BW information, that they deliberately coached the Japanese interviewees. The fear of Russia as the next major adversary was strong in Macarthur's eyes. <br />
The Soviet Union was so frustrated by this episode, that they had their own trial and sentenced many of the scientists they captured in Manchuria to various prison terms, from 1 to 30 years. Many of the top Japanese BW scientists, however, lived comfortably in Japan, and some went on to become respected scientists of international repute. <br />
Ishii continued to consult with American authorities, especially during the height of the Cold War, and died in 1959 of throat cancer. <br />
<br />
THE SOVIET UNION<br />
Russian outrage at the Japanese BW research and use may have been hypocritical. There are numerous reports that the Soviets themselves conducted studies involving human experimental subjects in Mongolia before and during the war. In one account, political prisoners and prisoners of war were chained in tents with pens of diseased rats until the subjects were bitten by the fleas. Supposedly, in the summer of 1941, one of the prisoner/experimental subjects escaped and began an epidemic that was controlled only because the Soviets bombed entire Mongol communities. It may never be known as to what extent Russia was involved in BW before, during, or after the war. <br />
<br />
THE UNITED STATES<br />
The U.S. army medical corps maintained a passing interest in BW since the 1920's. However, it was not until 1941 that the U.S. BW research program got off the ground, mainly because BW was viewed as a national security threat as the U.S. was drawn closer to the war. <br />
In 1937, Roosevelt declared that the U.S. would never resort to the use of chemical or biological weapons unless they were first used by the enemy. Roosevelt, however, had to agree to increased research in BW as America was being drawn into the war. <br />
The U.S. may have been one of the last major belligerent nations to research BW, but by the war's end the U.S. was probably the most advanced. By war's end, in August 1945, the U.S. BW effort employed 4,000 civilian and military workers, and vied with the Manhattan project for talented scientists and staff. <br />
In all, the U.S. spent $45-50 million for BW installations during the war. The installations included the main research station at Camp Detrick, Maryland, a field-test station on Horn Island in the Mississippi sound, and a huge field-testing facility at the dug way proving grounds in Utah. Also, an ordnance plant was constructed at Terre Haute, Indiana was converted into BW agent production center. <br />
Little is known about the U.S. BW research during the war. Most of the information is still heavily classified and may never be published. A 500 page monograph exists which details the U.S. effort during the war, but it is unavailable for publication because of its classification. <br />
From the flood of journal papers published, it is known that during the war the bacteria of anthrax, glanders, brucellosis, tularemia, meliodosis, and plague were studied. <br />
The fungus of coccidioimycosis was studied, as well as several plant .pathogens, including rice blast, rice brown-spot disease, late blight of potato, and stem rust of cereals. Also, animal pathogents such as rinderpest virus, newcastle disease virus, and fowl plague virus were studied. <br />
Of course, insects played a large role in the study of many of these diseases. Fleas, lice, the yellow fever mosquito, and the Colorado potato beetle were reared in large quantities. <br />
The U.S. also worked on aerosol transmission of pathogens, and freeze-drying of BW agents. <br />
Korea and the Cold War<br />
The U.S. BW research and development continued after WWII. As the cold war heated up, so did the BW effort at Fort Detrick. <br />
In 1952, China accused the U.S. of engaging in germ warfare against the people of North Korea. The Chinese began producing large amounts of evidence which suggested that the U.S. was spreading bacteria-laden insects and other objects over the Korean countryside. <br />
Also plague appeared in areas where it had not been documented for over 500 years. <br />
Chinese entomologists accused the U.S. of distributing disease-carrying anthomyid flies, springtails, and stoneflies with P-51 fighters. Also, accusations were leveled stating that America was contaminating areas with plague infested rats and fleas, and anthrax infested flies and spiders. In all, the U.S. was accused of dropping ants, beetles, crickets, fleas, flies, grasshoppers, lice, springtails, and stoneflies. The alleged associated diseases included anthrax, cholera, dysentery, fowl septicemia, paratyphoid, plague, scrub typhus, and typhoid. <br />
The Chinese set up an international scientific commission for investigating the facts about bacterial warfare. The commission, consisting of scientists from all over the world, ruled that the United States probably did engage in limited biological warfare in Korea. <br />
The U.S. maintains that the commission was nothing more than a communist front, however, and denied all the allegations. The U.S. proposed that the United Nations send a formal inquiry committee to China and Korea and investigate, but China and Korea refused. <br />
Most of the allegations were based on eyewitness reports, photographs of strange paper cartons, anomalous appearances of the insects in question, and testimony by POW's. <br />
It is strange why the Chinese would pick insects such as springtails and stoneflies and allege they were deliberately infected with disease and dropped on Korea. Clearly these insects would not be the best choices if the U.S. wanted to initiate BW. <br />
U.S. and Canadian entomologists claimed that the accusations were ridiculous and argued that the anomalous appearances of insects and appearances of new species to an area could be explained through natural phenomena. The U.S. wrote off the whole incident as communist propaganda, but speculation to this day exists as to whether the U.S. may have been experimenting in the field during the Korean war. <br />
Ten years later it was admitted by Dale Jenkins, the chief entomologist at Fort Detrick, that the U.S. at the time of the allegations was able to initiate BW if they saw fit and this BW would have involved insects as vectors of human diseases. Also, during the Korean War U.S. BW specialists were consulting heavily with former Japanese 731 scientists who were granted immunity from war crimes prosecution. <br />
Despite the allegations and negative press from the Korean war episode, BW research by the U.S. and Britain progressed at an accelerated pace through the 50's and 60's. Britain's BW effort tripled after WWII extensive fundamental research was done, including field testing, and promising results were passed on to the U.S. Top BW leaders in Britain and the U.S. grouped bioweapons in with atomic weapons as "weapons of mass destruction." They felt that situations might exist in which BW agents would be preferable to atomic weapons. <br />
In 1951, BW and chemical warfare were incorporated into official strategic planning by the armed forces of the U.S. Brig. General Rothchild, chemical officer of the Far East command, in 1953 wrote that BW could have played a vital role in the Korean War, by distributing anthrax or yellow fever pathogens into the cold air flows that travel from Siberia through the populated areas of China. <br />
Clearly, BW received strong support among the brass in the U.S. and British armed forces. By the end of the 50's the Fort Detrick labs were set up to breed 130 million yellow fever mosquitoes a month, infect them with yellow fever, and deliver them to the enemy via cluster bombs or from the warheads in a Sergeant Missile. Also, the facilities could accommodate the breeding of 50 million fleas per week. By 1960, the labs were experimenting with malaria, dengue, cholera, anthrax, and dysentery, relapsing fever, tularemia. <br />
The 1960's and Vietnam<br />
After the Cuban Missile Crisis, BW research and testing accelerated even further. President John F. Kennedy wished to balance the defense forces of the U.S. and therefore decided that BW and chemical weapons should be stepped up even further. <br />
In 1962, General Stubbs told congress that insect strains were being developed that were more cold hardy and were resistant to insecticides. All other information pertaining to BW involving insects during the 60's to the present have been classified and have not appeared in the congressional testimonies. <br />
In the early 60's, insects as BW vectors fell out of favor with the scientists and planners. This was due in large part to the successful development of dry biological formulations of toxins and microbes. <br />
With dry formulations of BW agents, the practicality and ease of disseminating diseases was greatly increased. It became easy for pneumonic plague, botulinum toxin, q-fever, and other diseases to be spread reliably and efficiently without the need for insects. <br />
Insects, however, were studied which could vector plant diseases. During the Cuban missile crisis, the U.S. considered destroying the sugarcane crop in Cuba with Fiji disease, which is vectored by leafhoppers. <br />
<br />
THE BIOLOGICAL WEAPONS CONVENTION<br />
In 1969, President Nixon called for the unilateral destruction of biological weapons. Three years later, the U.S. signed the Biological Weapons Convention Treaty, which banned the development, production, stockpiling, transfer, and acquisition of BW. In 1975, the U.S. also signed the Geneva Protocol of 1925, which also banned the use of these weapons in war. The treaties, however, do not ban research on BW. <br />
<br />
BIOLOGICAL WEAPONS TODAY<br />
BW development after 1975 virtually is unknown. Because all major nations signed the BW convention making BW illegal, little information is available as to what is going on today.DR. LAXMIKANT B. DAMAhttp://www.blogger.com/profile/13198225293462944168noreply@blogger.com0tag:blogger.com,1999:blog-4764725322678313110.post-57180727744040918892010-10-09T19:16:00.000-07:002010-10-09T19:16:41.013-07:00Zoology jobs<a href="http://www.blogtopsites.com/post/zoology">Zoology jobs</a><br />
click above link to reach to your destination (if u r willing to work with the subject)....<br />
check it out each job and accordingly choose your educational carrier...<br />
think over it...DR. LAXMIKANT B. DAMAhttp://www.blogger.com/profile/13198225293462944168noreply@blogger.com0tag:blogger.com,1999:blog-4764725322678313110.post-27287026633212171712010-10-09T18:59:00.001-07:002010-10-09T18:59:57.649-07:00insects in medicineINSECTS IN MEDICINE<br />
<br />
Insects and the substances extracted from them have been used as medicinal resources by human cultures all over the world. Besides medicine, these organisms have also played mystical and magical roles in the treatment of several illnesses in a range of cultures. Science has already proven the existence of immunological, analgesic, antibacterial, diuretic, anesthetic, and antirheumatic properties in the bodies of insects. Several authors have surveyed the therapeutic potential of insects, either recording traditional medical practices or employing insects and their products at the laboratory and/or clinical level. Thus, insects seem to constitute an almost inexhaustible source for pharmacological research. Chemical studies are needed to discover which biologically active compounds are actually present within insect bodies. The therapeutic potential of insects represents a significant contribution to the debate on biodiversity conservation, as well as opening perspectives for the economic and cultural valorization of animals traditionally regarded as useless. Their use needs to be at a sustainable level to avoid overexploitation insects. <br />
<br />
Insects and insect-derived products have been widely used in folk healing in many parts of the world since ancient times. Promising treatments have at least preliminarily been studied experimentally. Maggots and honey have been used to heal chronic and post-surgical wounds and have been shown to be comparable to conventional dressings in numerous settings. Honey has also been applied to treat burns. Honey has been combined with beeswax in the care of several dermatologic disorders, including psoriasis, atopic dermatitis, tinea, pityriasis versicolor, and diaper dermatitis. Royal jelly has been used to treat postmenopausal symptoms. Bee and ant venom have reduced the number of swollen joints in patients with rheumatoid arthritis. Propolis, a hive sealant made by bees, has been utilized to cure aphthous stomatitis. Cantharidin, a derivative of the bodies of blister beetles, has been applied to treat warts and molluscum contagiosum. Combining insects with conventional treatments may provide further benefit.<br />
Introduction: Why Insects?<br />
Insects and other arthropods provide ingredients that have been a staple of traditional medicine for centuries in parts of East Asia, Africa, and South America. While many of these ingredients have not been evaluated experimentally, an increasing number have been shown in preliminary trials to have beneficial properties. Although medical practitioners in more economically robust countries may prefer conventional treatments, it may be more a result of squeamishness rather than science. Furthermore, in parts of the world where conventional medical care is scarcer than arthropods used by folk healers, insects may represent a feasible substitute in some cases. In sub-Saharan Africa alone, the World Health Organization estimates that $20 billion will be needed to replace the shortage of 800,000 conventional health care workers by 2015. (1) Globally ubiquitous, arthropods potentially provide a cheap, plentiful supply of healing substances in an economically challenged world.<br />
Maggots<br />
The most well-studied medical application of arthropods is the use of maggots--the larvae of flies (most frequently that of Lucilia sericata, a blowfly) that feed on necrotic tissue .(2) Traditional healers from many parts of the world including Asia, South America, and Australia have used "larval therapy," (3) and records of physician use of maggots to heal wounds have existed since the Middle Ages. (3) Figure 1 depicts maggots on a wound.<br />
Fly larvae aid in wound healing via a number of mechanisms: (1) larval secretions break the larger adhesion molecules, fibronectin and collagen, into smaller fragments that promote fibroblast aggregation and tissue repair; (4) (2) larvae eat necrotic tissue that would otherwise form a nidus for infection, liquefying such tissue and aiding its digestion; (4) (3) maggots release antibacterial substances, some of which are produced by Proteus mirabilis bacteria that live naturally in the larval intestine; and (4) ingested bacteria are destroyed within maggots. (3)<br />
Maggots commercially grown under sterile conditions are used in wound healing. In one application technique, a hole is cut in a hydrocolloid dressing over a wound. (3) The maggots are lifted out of a container on a piece of nylon netting, which is folded together and taped onto the dressing over the hole after removal of the moisture in the maggot growth medium. A piece of gauze is placed over the nylon and taped in place. (3)<br />
[FIGURE 1 OMITTED]<br />
In one study, maggots were grown in vitro and placed in the wounds of 30 individuals after bacterial swabs of the wounds were taken. (5) The patients had arterial or venous stasis ulcers, diabetic or pressure ulcers, or chronic postoperative wounds. Secretions taken either from maggots grown on sterile plates or from wound sites sampled from 1-5 days after the introduction of larvae were studied for antibacterial properties. Larval secretions successfully suppressed Staphylococcus aureus growth in vitro. In vivo, 51 wounds (83.2%) healed, with reduced bacterial counts within the wounds.<br />
Maggots were also used to treat chronic leg wounds in several patient series. In one case series involving 34 leg wounds of at least three months duration in subjects ages 32-84, 85 percent of the wounds healed. (6) Of the healed wounds, 93 percent resolved within 7-10 days. In a second series, 70 patients, ages 25-94 with wounds of at least six weeks duration, were given treatment with one-day-old larvae added at a concentration of 5-10 larvae/[cm.sup.2]. (2) Eighty-six percent of the subjects had a 66- to 100-percent reduction of wound size. During treatment, 35 percent of subjects perceived more pain, 25 percent less pain, and 46 percent no difference in pain. In a third case series, larval therapy was applied to 70 chronic wounds; 43 percent of the wounds were completely debrided, and 29 percent were partially debrided. (7) There are also case reports of the successful use of maggots for treating the wound of a terminally ill patient (8) and for non-healing venous ulcers. (9)<br />
One study examined the factors that predict better outcomes of larval therapy in a series of 117 wounds. Greater wound depth, older patient age, and presence of septic arthritis portended a worse outcome. (10)<br />
Larval therapy has also been evaluated in controlled trials. In a randomized trial, 267 subjects with venous or arterial ulcers at least 25-percent covered with necrotic material were assigned to receive maggots or a conventional hydrogel dressing. (11) Although there was no difference in rate or timing of healing between groups, the maggot-treated wounds were debrided significantly faster (2.31 days; p< 0.001). On the other hand, subjects treated with maggots had a significantly higher pain score (approximately 40 points higher on a 150-point analog scale; p< 0001). In another trial involving diabetic leg ulcers, non-healing wounds were treated with either maggots, a conventional hydrogel, or the conventional therapy followed by larval treatment. (12) Wounds treated with maggots had significantly less necrotic tissue after two weeks. Thus, there is limited evidence that larval therapy can provide wound healing for lower extremity ulcers comparable to conventional treatment. A systematic review concluded that, in appropriate patients, use may be safe and effective. (13) Maggots may be appropriate especially when conventional therapies cannot be used, or in parts of the world where larvae are more easily obtainable than conventional treatment.<br />
Honey Treatment<br />
Honey is another insect-derived substance that has been used in wound healing and for treatment of other disorders, such as infections and irritable bowel syndrome. Therapeutic effects of honey have been documented from ancient times and it is still used in African folk medicine. (14, 15) Honey composition varies widely throughout the world depending on the species of bee and plants the bees feed on, both of which influence the honey's antioxidant and antimicrobial properties. (16-18) Four phenolic compounds in honey--p-hydroxybenzoic acid, naringenin, pinocembrin, and chrysin--are antimicrobials and antioxidants. The carbohydrate in honey is also antimicrobial. (16, 17) Honey also has antimutagenic properties. (19)<br />
Wound Healing<br />
The best studied use of honey is for wound healing. Honey promotes wound healing through osmotic properties that serve to moisturize the wound bed and reduce the risk of maceration. It also works via anti-inflammatory processes that reduce exudate and inhibit fibrin that adheres eschar to the wound bed, impairing tissue repair. (20)<br />
Honey has been used to heal wounds in numerous situations. Many studies have found dressings that contain honey comparable to conventional dressings. In a randomized, double-blind, placebo-controlled trial, 100 patients who had toenail surgery were assigned to receive either a honey-coated dressing or a conventional paraffin dressing. (21) There was no significant difference between groups in days taken to heal the wounds.<br />
However, in a single-blind study (blind to the investigator who examined the wounds), honey proved inferior in healing time to a conventional iodine dressing in 57 patients who had total avulsion toenail surgery, but comparable in wound-healing time to standard treatment after partial avulsion surgery. (22)<br />
n a case series, eight patients (ages 22-83) with leg wounds that had not healed in a month were given once- or twice-weekly applications of honey on a non-adhesive dressing. (23) After a month of treatment there was an average 54.8-percent reduction in wound size, from a baseline mean wound size of 5.62 to 2.25 [cm.sup.2]. (23)<br />
Two open (unblinded) trials also found significant wound healing with honey.DR. LAXMIKANT B. DAMAhttp://www.blogger.com/profile/13198225293462944168noreply@blogger.com0tag:blogger.com,1999:blog-4764725322678313110.post-84416720322619231532010-09-10T03:21:00.000-07:002010-09-10T03:21:06.303-07:00first internal marks<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtr3kHrcHAUMKSowM0wIgbUzxYq0iouWaoqyMPGWb5LlVfawDnjH6QcPWFTwHMe9rWdRVEGi7v2dlbiIqXyCyO5Lu-xSm08-LcG-2GpIjzqwVdDDLpvSjQ5WEAwXSuhS_g-DWSI3zKPAg/s1600/3.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtr3kHrcHAUMKSowM0wIgbUzxYq0iouWaoqyMPGWb5LlVfawDnjH6QcPWFTwHMe9rWdRVEGi7v2dlbiIqXyCyO5Lu-xSm08-LcG-2GpIjzqwVdDDLpvSjQ5WEAwXSuhS_g-DWSI3zKPAg/s640/3.JPG" width="578" /></a></div>DR. LAXMIKANT B. DAMAhttp://www.blogger.com/profile/13198225293462944168noreply@blogger.com0tag:blogger.com,1999:blog-4764725322678313110.post-60282289869648338382010-09-07T17:42:00.000-07:002010-09-07T17:42:00.527-07:00antennaThe antenna<br /><br />The antenna are a pair of jointed appendages articulated with the head in front of the eyes or between them. The antenna vary greatly in form; in some insects they are thread-like, consisting of a series of similar segments; in others certain segments are greatly modified. The thread-like form is the more generalized.<br /><br />In descriptive works names have been given to particular parts of the antennae, as follows (Fig. 5 i):<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZypwj67h2CezmgzvaglxWGTVU-ZTRcdcnruGrRc-VFDM0msWo9B6gt6Zm4sU7D_aSZL7Mad3DpNU6nwWlaaM1mjKc8Lz1E8zovjQ4ts2fNlj86ASyhNnoHyf6aVNRxwbEbAIlr1XODDk/s1600/antenna.bmp"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 320px; height: 320px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZypwj67h2CezmgzvaglxWGTVU-ZTRcdcnruGrRc-VFDM0msWo9B6gt6Zm4sU7D_aSZL7Mad3DpNU6nwWlaaM1mjKc8Lz1E8zovjQ4ts2fNlj86ASyhNnoHyf6aVNRxwbEbAIlr1XODDk/s320/antenna.bmp" alt="" id="BLOGGER_PHOTO_ID_5512482126803983266" border="0" /></a>The Scape.—The first or proximal segment pf an antenna is called the scape (a). The proximal end of this segment is often subglobose, appearing like a distinct segment; in such cases it is called the bulb (a1).<br /><br />Pedicel—The pedicel is the second segment of an antenna (b). In it differs greatly in form from the other segments.<br /><br />The Clavola.—The term clavola is applied to that part of the antenna distad of the pedicel (c) ; in other words, to all of the antenna except the 1st and second segments. In some insects certain parts of the clavola are specialised antenna and have received particular names. These are the ring-joints, the funicle, and the club.<br /><br />Ring-joints.—In certain insects (e.g., Chalcididae) the proximal segment or segments of the clavola are much shorter than the proceeding segments; in such cases they have received the name of ring-joins (c1).<br /><br />The Club.—In many insects the distal segments of the antennae are more or less enlarged.<br /><br />in such cases they are termed the club (c2).<br /><br />The Funicle.—The funicle (e’) is that part of the clavola between the dub and the ring joints; or, when the latter are not specialized, between the club and the pedicel.<br /><br />The various forms of antennae are designated by special terms. The more common of these forms are represented in Fig. 52. They are as follows: -<br /><br />1. Setaceous : or bristle-like, in which the segments are successively smaller and smaller,<br /><br />the whole organ tapering to a -point.<br /><br />2. Filiform : or thread-like, in which the segments are of nearly uniform thickness.<br /><br />3.Moniliform: or necklace-form, in which ‘the segments are more or less globosa, suggesting a string of beads.<br /><br />4. Serrate: or saw-like, in which the segments are triangular and project like the teeth of a saw.<br /><br />5. Pectinate : or comb-like, in which the segments have long processes on one side, like the teeth of a comb).<br /><br />6. Clavate :club-shaped, in which the segments become gradually broader, so that the whole organ assumes the form of a club.<br /><br />7. Copitate : or with a head, in which the terminal segment or segments form a large knob.<br /><br />8. Lamellate: in which the segments that compose the knob are extended on one side into broad plates.<br /><br />9. Geniculate: When an antenna is bent abruptly at an angle like a bent knee (Fig. 5) it is<br /><br />said to be geniculate.<br /><br />10. Aristate: (in house fly) pouch-like with lateral bristle on last clubbed segment.<br /><br />11. Plumose: (brush-like) in mosquito.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcDampM-cG79HIxHWuCl45JNhByOryGWlJqxRJ1Og6OkuWN_7fXHRtxT5YEfkiRzNrDZSDg1ULSUgwhlfy3pNFRt5sQiLqdjWNQu0NdC4VyO_ctcnQjRoVvhzT494Dvwhnx2OCBvLOKPw/s1600/types+of+antenna.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 320px; height: 318px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcDampM-cG79HIxHWuCl45JNhByOryGWlJqxRJ1Og6OkuWN_7fXHRtxT5YEfkiRzNrDZSDg1ULSUgwhlfy3pNFRt5sQiLqdjWNQu0NdC4VyO_ctcnQjRoVvhzT494Dvwhnx2OCBvLOKPw/s320/types+of+antenna.jpg" alt="" id="BLOGGER_PHOTO_ID_5512482134115776770" border="0" /></a>DR. LAXMIKANT B. DAMAhttp://www.blogger.com/profile/13198225293462944168noreply@blogger.com1tag:blogger.com,1999:blog-4764725322678313110.post-22591318999305339702010-09-07T05:27:00.000-07:002010-09-07T05:27:00.099-07:00Simple eye<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_hlDixNCqb6IRh1cpLQAUQi4WJJOmfzlpRD-GoWHcJSlDo05nfIi0Y95FpXPHya4_tV06zV-MiLSN-HNae6JzQ7WAEUv2P0SJf48kfGc9ETWAvBVeCMOSAS1EUNVLSDOgZFEiSrXV3FU/s1600/ocili.JPG"><br /></a><br />THE ORGANS OF PHOTORECEPTION<br />A. THE GENERAL FEATURES<br />The two types of eyes of insects.—insects possess two types of eyes, the ocelli or simple eyes and the compound or facetted eyes. Typically both types of eyes are present in the same insect, but either may be absent. Thus many adult insects lack ocelli, while the larva of insects with a complete metamorphosis lack compound eyes. When all are present there are two compound eyes and, typically two pairs of ocelli; but almost invariably the members of one pair of ocelli are united and form a single median ocellus The median ocellus is absent in many insects that possess the other two ocelli. The distinction between ocelli and compound eyes.—The most obvious distinction between ocelli and compound eyes is the fact that in an ocellus there is a single cornea while in a compound eye there are many. Each ommatidium of a compound eye has been considered as a separate eye because its nerve-endings constituting the retinula are isolated from the retinube of other ommatidia by surrounding accessory pigment cells; but a similar isolation of retinui exist in some ocelli. It has also been held that in compound eyes there is a layer of cells between the corneal hypodermis and the retinas. the crystalline-cone- cells, which is absent in ocelli; but in the ocelli of adult Ephemerida there is a layer of cells between the lens and the retina, which, at least, is in a position analogous to that of the crystallinecone-cells; the two may have had a different origin, but regarding this, we have, as yet, no conclusive data.<br /><br />The absence of compound eyes in most of the Apterygota.—<br />Typically insects possess both ocelli and compound eyes; when either kind of eyes is wanting it is evidently due to a; loss of these organs and<br />not to a generalized condition. Although compound eyes are almost universally absent in the Apterygota-in the few cases where they are present in this group they are of a highly developed type and not rudimentary; the compound eyes of Machills, for example, are as perfect as those of winged insects.<br /><br />The absence of compound eyes in 1arve.—<br />The absence. of compound eyes in larva is evidently a secondary adaptation to their particular mode of life, like the internal development of wings in the same forms. In the case of the compound eyes of larva, the development of the organs is retarded, taking place in the pupal stage instead of in an embryonic stage, as is the case with nymphs and naiads. While, the development of the compound eyes as a whole is retarded in larva, a few ommatidia may be developed and function as ocelli during larval life.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_hlDixNCqb6IRh1cpLQAUQi4WJJOmfzlpRD-GoWHcJSlDo05nfIi0Y95FpXPHya4_tV06zV-MiLSN-HNae6JzQ7WAEUv2P0SJf48kfGc9ETWAvBVeCMOSAS1EUNVLSDOgZFEiSrXV3FU/s1600/ocili.JPG"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 291px; height: 320px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_hlDixNCqb6IRh1cpLQAUQi4WJJOmfzlpRD-GoWHcJSlDo05nfIi0Y95FpXPHya4_tV06zV-MiLSN-HNae6JzQ7WAEUv2P0SJf48kfGc9ETWAvBVeCMOSAS1EUNVLSDOgZFEiSrXV3FU/s320/ocili.JPG" alt="" id="BLOGGER_PHOTO_ID_5512480349423402450" border="0" /></a><br />B. THE OCELLI: There are two classes of ocelli found in insects: first, the ocelli of adult insects and of nymphs and naiads, which may be termed the primary ocelli; and second, the ocelli of most larva possessing ocelli, which may be termed adaptive ocelli.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhMjqvddp-Fryc9zD1EVTkNelymRz0fmaqt0jUv91YC-2YPLhlDiurVOOhdLV8ZoonfbQNzjWqsR9P0MTBPoDYwBQgGxZ49QvROCjO4h8yLRk44uno-VRnnkPXXu7_I7gynhBoKTtm2LYQ/s1600/image+3.JPG"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 189px; height: 320px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhMjqvddp-Fryc9zD1EVTkNelymRz0fmaqt0jUv91YC-2YPLhlDiurVOOhdLV8ZoonfbQNzjWqsR9P0MTBPoDYwBQgGxZ49QvROCjO4h8yLRk44uno-VRnnkPXXu7_I7gynhBoKTtm2LYQ/s320/image+3.JPG" alt="" id="BLOGGER_PHOTO_ID_5512478771599783330" border="0" /></a><br />The primary ocelli.—The ocelli of adult insects and of nymphs and naiads having been originally developed as ocelli are termed the primary ocelli. Of these there are typically two pairs; but usually when they are present there are only three of them, and in many cases only a single pair. When there are three ocelli, the double nature of the median ocellus is shown by the fact that the root of the nerve is double, while that of each of the other two is single. In certain generalized insects, as some Plecoptera, (Fig. 150) all of the ocelli are situated in the front; but in most insects, the paired ocelli have either migrated into the suture between the front and the vertex (Fig. xi), or have proceeded farther and are situated in the vertex.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirkKeXlxiYyIE7mic-U2uzMSzZifvrBnanmGxJ3zUq2QORZJWe7auDbs3f8AL8uKJ7MPmNf12OIjivcHj0GViM2Kb35AjHuil5OGmmYMaRjouSlTm3L95CsxsZRQj90fHK7WeH9D9nPsc/s1600/image2.JPG"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 142px; height: 320px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirkKeXlxiYyIE7mic-U2uzMSzZifvrBnanmGxJ3zUq2QORZJWe7auDbs3f8AL8uKJ7MPmNf12OIjivcHj0GViM2Kb35AjHuil5OGmmYMaRjouSlTm3L95CsxsZRQj90fHK7WeH9D9nPsc/s320/image2.JPG" alt="" id="BLOGGER_PHOTO_ID_5512478762616691490" border="0" /></a><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtGnkTSq2OsjtebAHjs5emSSENKSgtrkOzW7AsB_sTM1U4I8MHmqHeQOAdnGx_PkXoZb_N8T4IQnkBLeWIrCfRzt1mR1yHFsVfK77UZYE7lMC2goP76OOHUJ9s22l-VwFPSShNsZzURgE/s1600/image+5.JPG"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 262px; height: 320px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtGnkTSq2OsjtebAHjs5emSSENKSgtrkOzW7AsB_sTM1U4I8MHmqHeQOAdnGx_PkXoZb_N8T4IQnkBLeWIrCfRzt1mR1yHFsVfK77UZYE7lMC2goP76OOHUJ9s22l-VwFPSShNsZzURgE/s320/image+5.JPG" alt="" id="BLOGGER_PHOTO_ID_5512478779630403378" border="0" /></a><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNyEKPJtbKMDZqGSjw2sIFsCulh6ZouEzYZCjr4Cuirw0pgvDx6OVOVAv9R5WH5dOr9HVjQfWS_GgpU9hTwQlZ1c05zSS9LJQwS20V33WrD6JWDHNOLfsTPcZCvqSkp37l9QtQJWZmRqo/s1600/image+4.JPG"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 212px; height: 320px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNyEKPJtbKMDZqGSjw2sIFsCulh6ZouEzYZCjr4Cuirw0pgvDx6OVOVAv9R5WH5dOr9HVjQfWS_GgpU9hTwQlZ1c05zSS9LJQwS20V33WrD6JWDHNOLfsTPcZCvqSkp37l9QtQJWZmRqo/s320/image+4.JPG" alt="" id="BLOGGER_PHOTO_ID_5512478777515843282" border="0" /></a>DR. LAXMIKANT B. DAMAhttp://www.blogger.com/profile/13198225293462944168noreply@blogger.com0tag:blogger.com,1999:blog-4764725322678313110.post-7039677011946139552010-09-06T17:24:00.000-07:002010-09-06T17:24:00.177-07:00Cuticular appendagesCuticular appendages:<br />Cuticular structural components, waxes, cements, pheromones (Chapter 4), and defensive and other compounds are products of the epidermis, which is a near continuous, single-celled layer beneath the cuticle. Many of these compounds are secreted to the outside of the insect epicuticle. Numerous fine pore canals traverse the procuticle and then branch into numerous finer wax canals (containing wax filaments) within the epicuticle (enlargement in Fig. 1); this system transports lipids (waxes) from the epidermis to the epicuticular surface. The wax canals may also have a structural role within the epicuticle. Dermal glands, part of the epidermis, produce cement and/or wax, which is transported via larger ducts to the cuticular surface. Wax-secreting glands are particularly well developed in mealybugs and other scale insects. The epidermis is closely associated with molting – the events and processes leading up to and including ecdysis (eclosion), i.e. the shedding of the old cuticle. Insects are well endowed with cuticular extensions, varying from fine and hair-like to robust and spine-like. Four basic types of protuberance (Fig. 2), all with sclerotized cuticle, can be recognized on morphological, functional, and developmental grounds:<br />1. Spines are multicellular with undifferentiated epidermal cells;<br />2. Setae, also called hairs, macrotrichia, or trichoid sensilla, are multicellular with specialized cells;<br />3. acanthae are unicellular in origin;<br />4. microtrichia are subcellular, with several to many extensions per cell.<br />Setae sense much of the insect’s tactile environment. Large setae may be called bristles or chaetae, with the most modified being scales, the flattened setae found on butterflies and moths (Lepidoptera) and sporadically elsewhere. Three separate cells form each seta, one for hair formation (trichogen cell), one for socket formation (tormogen cell), and one sensory cell (Fig. 4.1). There is no such cellular differentiation in multicellular spines, unicellular acanthae, and subcellular microtrichia. The functions of these types of protuberances are diverse and sometimes debatable, but their sensory function appears limited. The production of pattern, including color, may be significant for some of the microscopic projections. Spines are immovable, but if they are articulated, then they are called spurs. Both spines and spurs may bear unicellular or subcellular processes.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixLLajjK5DgqWkpATzfC0bwgklhVOSuNuU-PQRdl9SRazdnnhQjfKO2ufLaK834Si1fECCokY8uCOPN3QhZR8N42PV0q9tlsN37ugVTm2yrGfFppcXgQ6cOS7DjFv7aPW_azV7bWtmyMs/s1600/image1.JPG"><br /></a><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3h915H0HLJfT2aAjFVUzCBu6hqUOLckGl4HfiyQz5amm-8XerXo_HT4EGvwbMfYp1UcrSOAYuYVA4no4oFB1zx7ZSS6eCd7foiwvrzk4dntA0xGvcKqKAb0_h00VdVg-gAw2BaL3bdrs/s1600/image5.JPG"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 201px; height: 320px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3h915H0HLJfT2aAjFVUzCBu6hqUOLckGl4HfiyQz5amm-8XerXo_HT4EGvwbMfYp1UcrSOAYuYVA4no4oFB1zx7ZSS6eCd7foiwvrzk4dntA0xGvcKqKAb0_h00VdVg-gAw2BaL3bdrs/s320/image5.JPG" alt="" id="BLOGGER_PHOTO_ID_5512474712542721986" border="0" /></a><br />Fig. 1 The general structure of insect cuticle; the enlargement above shows details of the epicuticle.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixLLajjK5DgqWkpATzfC0bwgklhVOSuNuU-PQRdl9SRazdnnhQjfKO2ufLaK834Si1fECCokY8uCOPN3QhZR8N42PV0q9tlsN37ugVTm2yrGfFppcXgQ6cOS7DjFv7aPW_azV7bWtmyMs/s1600/image1.JPG"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 320px; height: 254px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixLLajjK5DgqWkpATzfC0bwgklhVOSuNuU-PQRdl9SRazdnnhQjfKO2ufLaK834Si1fECCokY8uCOPN3QhZR8N42PV0q9tlsN37ugVTm2yrGfFppcXgQ6cOS7DjFv7aPW_azV7bWtmyMs/s320/image1.JPG" alt="" id="BLOGGER_PHOTO_ID_5512474374405552914" border="0" /></a><br />Fig. 2 The four basic types of cuticular protuberances: (a) a multicellular spine; (b) a seta, or trichoid sensillum; (c) acanthae; and (d) microtrichia.DR. LAXMIKANT B. DAMAhttp://www.blogger.com/profile/13198225293462944168noreply@blogger.com1tag:blogger.com,1999:blog-4764725322678313110.post-19700820051099620732010-09-04T05:12:00.000-07:002010-09-04T05:12:00.315-07:00Functions of the IntegumentFunctions of the Integument<br /><br />Most functions of the integument relate to the physical structure of the cuticle though the latter may serve as a source of metabolites during periods of starvation. The primary functions may be discussed under three headings: strength and hardness, permeability, and production of color.<br /><br /><br />1. Strength and Hardness<br /><br />The few studies that have been carried out on the mechanical properties of insect cuticle indicate that is of medium rigidity and low tensile strength (Locke, 1974). There is, however, wide variation from this general statement; for example, the cuticles of most endopterygote larvae are extremely plastic, whereas the mandibular cuticle of many biting insects may be extremely hard, enabling them to bite through metal. Further, there is an obvious difference<br />in properties between sclerites and intersegmental membranes, and between typical non- elastic cuticle and that which contains a high proportion of resilin.<br />Though the above properties indicate that the cuticle is satisfactory as a “skin” pre- enting physical damage to internal organs, discussion of the suitability of the cuticle as a skeletal component must include an appreciation of overall body structure (Locke, 1974). Most components of insect (and other arthropod) bodies may be considered as cuticular cylinders or spheres. Such a tubular shell (used here in the engineering sense to mean a surface-supporting structure that is thin in relation to total size) is about three times as strong as a solid rod of the same material having the same cross-sectional area as the shell<br />(i.e., they both contain the same amount of skeletal material). The force required to dis- tort the shell is proportional to the thickness of the shell and inversely proportional to the cross-sectional area of the whole body. Thus, in small organisms where the thickness of the shell is great relative to the cross-sectional area of the body, the use of a shell as an xoskeletal structure is quite feasible. In larger organisms the advantage of the extra strength relating to a shell type of skeleton is greatly outweighed (literally as well as metaphori-<br />cally) by the massive increase in thickness of the shell that would be required and, perhaps,<br />by the physiological problems of producing the large amounts of material required for its construction.<br /><br /><br />4.2. Permeability<br /><br />For different insects there exists a wide range of materials that are potential permeants<br />of the integument, and of factors that affect their rate of permeation. Sometimes specific regions of the integument are constructed to facilitate entry or exit of certain materials; more often the integument is structured to prevent entry or loss. At this time we shall consider only the permeability of the cuticle to water and insecticides, of which the latter may now be considered a normal hazard for most insects. The passage of gases through the integument<br />is considered in Chapter 15.<br />Water. Water may be either lost or gained through the integument. In terrestrial insects, which exist in humidities that are almost always less than saturation, the problem is to prevent loss through evaporation. In freshwater forms the problem is to prevent entry related to osmosis.<br />In many terrestrial insects the rate of evaporative water loss is probably less than 1% per hour of the total water content of the body (i.e., of the order of 1–3 mg/cm2 per hr for most species). Most of this loss occurs via the respiratory system, despite the evolution of mechanical and physiological features to reduce such loss (Chapter 15). Water loss through the integument (sensu stricto) is extremely slight, mainly because of the highly impermeable epicuticle and in particular the wax components. Early experiments demonstrated that permeability of the integument is relatively independent of temperature up to a certain point (the transition temperature), above which it increases markedly. As a result of his studies on both artificial and natural systems, Beament (1961) concluded that the initial impermeability is related to the highly ordered wax monolayer whose molecules sit on the tanned cuticulin envelope at an angle of about 25 to the perpendicular axis, with their polar ends facing inward and nonpolar ends outward. In this arrangement the molecules are closely packed and held tightly together by van der Waals forces. As temperature increases, the molecules gain kinetic energy, and eventually the bonds between them rupture. Spaces appear and water loss increases significantly. The nature of the wax and its transition temperature can be correlated with the normal niche of the insect. Insects from humid environments or that have access to moisture in their diet, for example, aphids, caterpillars, and bloodsucking insects, have “soft” waxes, with low transition temperatures. Forms from dry environments or stages with water-conservation problems, for example, eggs and pupae, are covered with “hard” wax, whose transition temperature is high (in most species above the thermal death point of the insect).<br />More recent studies have questioned the validity of Beament’s ordered monolayer model. Evidence against it includes the observation that hydrocarbons (non-polar molecules) are the dominant component of wax, physicochemical analyses that indicate that the lipids have no preferred orientation, and mathematical calculations that show the abrupt permeability changes at the so-called transition point to be artifactual (Blomquist and Dillwith, 1985).<br />Some insects that are normally found in extremely dry habitats and may go for long periods without access to free water, for example, Tenebrio molitor and prepupae of fleas, are able to take up water from an atmosphere in which the humidity is relatively high.<br />Originally it was believed that uptake occurred across the body surface perhaps via the pore canals. However, it has now been demonstrated that uptake occurs across the wall of the rectum (Chapter 18, Section 4.1).<br />In many freshwater insects, for example, adult Heteroptera and Coleoptera, the cuticle is highly impermeable because of its wax monolayer and water gain is probably 4% or less of the body weight per day. In most aquatic insects, however, the wax layer is absent. Thus, gains of up to 30% of the body weight per day are experienced, the excess water being removed via the excretory system (Chapter 18, Section 4.2).<br />Insecticides. Economic motives have stimulated an enormous interest in the perme- ability of the integument to chemicals, especially insecticides and their solvents (Ebeling,1974). Though, for the most part, the cuticle acts as a physical barrier to decrease the rate of entry of such materials, there is evidence that in some insects it may also bring about metabolic degradation of certain compounds, and consequently reduction of their potency.<br />It follows that increased resistance to a particular compound may result from changes in ei- ther the structure or the metabolic properties of the integument (see also Chapter 16, Section 5.5). For most insects, the primary barrier to the entrance of insecticides is the epicuticular wax, which dissolves and retains these largely lipid-soluble materials. For the same reason, the cement layer also probably provides some protection against penetration. The procuti- cle offers both lipid and aqueous pathways along which an insecticide may travel, but the precise rate at which a compound moves depends on many variables, especially thickness of the cuticle, presence or absence of pore canals, and whether the latter are filled with cytoplasmic extensions or other material. It follows that the rate of penetration will vary according to the 1ocation of an insecticide on the integument. However, it has also been noted that dissolution in the wax will facilitate lateral movement of the insecticides, perhaps allowing them to reach the tracheal system and thus gain access. Thin, membranous cuticle such as occurs in intersegmental regions or covers tactile or chemosensory hairs generally provides little resistance to penetration. The tracheal system is another site of entry. The extent to which tanning of the procuticle occurs is also related to penetration rate. As the chitin-protein micelles become more tightly packed and the cuticle partially dehydrated, permeability decreases.<br />In addition, but obviously related to the physical features of the cuticle, the physico- chemical nature of an insecticide is an important factor in determining the rate of entry. Especially significant is the partition coefficient (the relative solubility in oil and in water) of an insecticide or its solvent. In order to penetrate the epicuticular wax the material must be relatively lipid-soluble. However, in order to pass through the relatively polar procuti- cle and, eventually, to leave the integument to move toward its site of action, the material must be partially water-soluble. Thus, correct formulation of an insecticidal solution is an important consideration.<br />It should be apparent from the above discussion that few generalizations can be made.<br />At the present time, therefore, the suitability of an insecticide must be considered separately for each species. Because of the factors that affect the entry of insecticides, a great difference usually exists between “real toxicity,” that is, toxicity at the site of action, and “apparent toxicity,” the amount of material that must be applied topically to bring about death of the insect. The chief feature that relates the two is obviously the “penetration velocity,” that is, the rate at which material passes through the cuticle. When the rate is high, the real and apparent toxicity values will be nearly identical.<br />4.3. Color<br />As in other animals, the color of insects serves to conceal them from predators (some- times through mimicry), frighten or “warn” predators that potential prey is distasteful, or facilitate intraspecific and/or sexual recognition. It may be used also in thermoregulation. The color of an insect generally depends on the integument. Rarely, an insect’s color may be the result of pigments in tissues or hemolymph below the integument. For example, the red color of Chironomus larvae is caused by hemoglobin in solution in the hemolymph. Integumental colors may be produced in two ways. Pigmentary colors are produced when pigments in the integument (usually the cuticle) absorb certain wavelengths of light and reflect others (Fuzeau-Bresch, 1972). Physical (structural) colors result when light waves of a certain length are reflected as a result of the physical features of the surface of the integument.<br />Pigmentary colors result from the presence in molecules of particular bonds between atoms. Especially important are double bonds such as C C, C O, C N, and N N which absorb particular wavelengths of light (Hackman, 1974; Kayser, 1985). The integument may contain a variety of pigment molecules that produce characteristic colors. Usually the molecule, known as a chromophore, is conjugated with a protein to form a chromo- protein. The brown or black color of many insects results usually from melanin pigment. Melanin is a molecule composed of polymerized indole or quinone rings. Typically, it is located in the cuticle, but in Carausius it occurs in the epidermis, where it is capa- ble of movement and may be concerned with thermoregulation as well as concealment. Carotenoids are common pigments of phytophagous insects. They are acquired through feeding as insects are unable to synthesize them. Carotenoids generally produce yellow, orange, and red colors, and, in combination with a blue pigment, mesobiliverdin, produce green. Examples of the use of carotenoids include the yellow color of mature Schistocerca and the red color of Pyrrhocoris and Coccinella. Pteridines, which are purine derivatives, are common pigments of Lepidoptera, Hymenoptera, and the hemipteran Dysdercus, and produce yellow, white, and red colors. Ommochromes, which are derivatives of trypto- phan, an amino acid, are an important group of pigments that produce yellow, red, and brown colors. Examples of colors resulting from ommochromes are the pink of immature adult Schistocerca, the red of Odonata, and the reds and browns of nymphalid butter- flies. In some insects the characteristic red or yellow body color is the result of flavones originally present in the foodplant. Uric acid, the major nitrogenous excretory product of insects (Chapter 18, Section 3.1), is deposited in specific regions of the epidermis in some insects. For example, in Dysdercus it is responsible for the white areas of the integument.<br />Physical colors are produced by scattering, interference, or diffraction of light though the latter is extremely rare. Most white, blue, and iridescent colors are produced using the first two methods. White results from the scattering of light by an uneven surface or by granules that occur below the surface. When the irregularities are large relative to the elength of light, all colors are reflected equally, and white light results. An interference color is produced by laminated structures when the distance between successive laminae is similar to the wavelength of light that produces that particular color. As light strikes the laminae light waves of the “correct” length will be reflected by successive surfaces, and the color they produce will therefore be reinforced. Light waves of different lengths will be out of phase. Changing the angle at which light strikes the surface (or equally the angle at which the surface is viewed) is equivalent to altering the distance between laminae. In turn, this will alter the wavelength that is reinforced and color that is produced. This change of color in relation to the angle of viewing is termed iridescence. Iridescent colors are common in many Coleoptera and Lepidoptera.<br /><br /><br />4.4. Other Functions<br /><br />The cuticular waxes may have important roles in preventing the entry of microorganisms and in chemical communication (i.e., they serve as semiochemicals). It has been suggested that the waxes may prevent adhesion of microorganisms or may be toxic to them. Cuticular hydrocarbons are also known to serve as contact sex pheromones, for example, in female Diptera and Blattella, attracting or inducing copulatory behavior in males, or serving as<br />an aphrodisiac to keep the male in position until insemination has occurred (Schal et al 1998). In termites, the cuticular hydrocarbon blend is highly specific and serves as a species- and/or caste-recognition pheromone. (See also Chapter 13, Section 4.1.2.) Interestingly, some beetles that live in termite colonies produce the same hydrocarbon profile as the host, enabling them to remain unmolested in the nest. The species-specific nature of the lipids has been turned to advantage by some parasitic Hymenoptera who use these chemical cues (known as kairomones [Chapter 13, Section 4.2.) to locate their host (Blomquist and Dillwith, 1985).DR. LAXMIKANT B. DAMAhttp://www.blogger.com/profile/13198225293462944168noreply@blogger.com0tag:blogger.com,1999:blog-4764725322678313110.post-91938783040556366302010-09-04T05:09:00.000-07:002010-09-04T05:09:00.168-07:00Cuticle structureCuticle<br />The cuticle is secreted by the epidermis and covers the whole of the outside of the body as well as lining the foregut and hindgut and the tracheal system, which are formed as in- vaginations of the epidermis. Most of the cuticle is composed of a mixture of proteins and the polysaccharide chitin. Out- side this chitinous cuticle is a chemically complex epicuticle that does not contain chitin. It is only a few microns thick.<br /><br />Chitinous cuticle<br />Chitin occurs as long molecules that are bound together to form microfibrils. These microfibrils lie parallel to the plane of the surface and, at any depth below the surface, to each other. In successive layers the orientation changes, usu- ally giving rise to a helicoid (spiral) arrangement through the thickness of the cuticle. This gives strength to the cuticle in all directions. Sometimes layers of helicoidally arranged mi- crofibrils alternate with layers in which the microfibrils have a consistent orientation. These layers differ in their refractive indexes, and the metallic colors of insects typically are the re- sult of differences in the optical properties of the successive layers, so that only specific wavelengths of light are reflected.<br /><br />The helicoid arrangement of microfibrils provides strength to the cuticle, but it does not impart hardness or rigidity. Hard- ness in insect cuticle derives from the linking together of pro- teins. The process of linking the proteins is called sclerotization, and the hardened cuticle that results is said to be sclerotized or tanned. Hardening is restricted to the outer parts of chitinous cuticle, so that the cuticle becomes differentiated into the outer sclerotized exocuticle and an inner endocuticle that remains un- sclerotized. Sclerotization does not take place until the cuticle is expanded fully after a molt and depends on the transport of chemicals from the epidermis. This is achieved via a series of slender processes of the epidermal cells that extend through the chitinous cuticle, creating canals in the cuticle that run at right angles to the surface. These are called pore canals.<br /><br />Sclerotization affords some rigidity in addition to hard- ness, but in many areas of the cuticle this rigidity is enhanced by shallow folds in the cuticle. Their effect is comparable to that of a T-girder. The folds are seen as grooves, called sulci (singular: “sulcus”), on the outside of the cuticle. Sulci are most common on the head and thorax, where they define ar- eas of cuticle that are given specific names. Additional rigid- ity is achieved where fingerlike inpushings of the cuticle, called apodemes, meet internally, forming an endophragmal skeleton. This occurs in the head of all insects, where two pairs of apodemes, originating anteriorly and posteriorly on the head, join beneath the brain to form the tentorium, which provides the head with great rigidity in the horizontal plane. In winged insects lateral and ventral apodemes in the thorax may join or be held together by muscles forming a strut that holds the sides (pleura) of the thorax rigid with respect to the ventral surface (sternum). This is essential for the movement of the wings in flight. The tubular form of the legs and other appendages makes them rigid.<br /><br />Flexibility in the cuticle, which allows different parts of the body to move with respect to each other, depends on regions of movable cuticle between the hardened plates (sclerites). Sclerotization does not occur in this flexible cuticle, which is referred to as “membranous.” It is most extensive in the re- gion of the neck, between the abdominal segments, and between segments of the appendages. Membranous cuticle also is found where the wings join the thorax and at the bases of the antennae, mouthparts, and other appendages, giving them freedom to move. Precision of movement is achieved by points of articulation at which there is only a very small re- gion of membrane between adjacent sclerites.<br /><br />A rubberlike protein, called resilin, also is known to be pre- sent in some insects and may occur more widely. When it is distorted, it retains the energy imparted to it and, like a rubber ball, returns to its original shape when the tension is re- leased. There is a pad of resilin in the hind wing hinge of the locust and also in the side of the thorax of the flea, where the release of stored energy gives rise to the jump. Small amounts also are present in the hinge of the labrum in the locust and in the abdomen of some beetles.<br />The strength, rigidity and articulations of the cuticle pro- vide the insect with support, protection, and precision of movement. In larval forms, such as caterpillars and fly larvae, most of the cuticle remains unsclerotized. In these cases, the hemolymph (insects’ blood) functions as a hydrostatic (held by water pressure) skeleton, and movements are much less precise.<br />Epicuticle<br />Three or, in some species, four chemically distinct layers are present in the epicuticle. The innermost layer (inner epi- cuticle) contains lipoproteins but is chemically complex. Its functions are unknown. The next layer, the outer epicuticle, is made of polymerized lipid, though it probably also contains some protein. It is believed to be inextensible, such that it can unfold but not stretch. It defines the details of patterns on the surface of the cuticle. Outside the outer epicuticle is a layer of wax. This comprises a mixture of chemical compounds whose composition varies considerably between insect taxa. The wax limits water loss through the cuticle and so is a major feature contributing to the success of insects as terrestrial organisms, for whom water is at a premium. Because this layer becomes abraded (worn away) during normal activities, it has to be renewed continually. New compounds are synthesized in the epidermis and are thought to be transported to the sur- face via wax canal filaments that run through the pore canals and the inner and outer epicuticles. A fourth layer sometimes occurs outside the wax, but its functions are unknown.<br /><br />Epidermis<br />The epidermis is a single layer of cells. In addition to pro- ducing the cuticle, it contains many glands that secrete chem- icals to the outside of the insect. These chemicals include many pheromones, involved in communication with other members of the same species, and defensive compounds that often are repellent to potential enemies. In the latter case, the glands frequently include a reservoir in which the noxious substances are accumulated until they are needed.DR. LAXMIKANT B. DAMAhttp://www.blogger.com/profile/13198225293462944168noreply@blogger.com0tag:blogger.com,1999:blog-4764725322678313110.post-85854153433536581182010-09-02T16:41:00.001-07:002010-09-02T17:05:49.848-07:00Insect HeadThe Head<br /><br />The head, being the anterior tagma, bears the major sense organs and the mouth parts. Considerable controversy still surrounds the problem of segmentation of the insect head, especially concerning the number and nature of segments anterior to the mouth. At various times it has been argued that there are from three to seven segments in the insect head, though it is now widely agreed that there are six.<br /><br />The embryological studies have demonstrated convincingly that an acron is present. However, it is never seen in fossil insects or other arthropods because it moved dorsally to merge imperceptibly into the region between the compound eyes. Both embryology and paleontology have confirmed that there are three preoral and three postoral segments The first preoral segment is preantennal; it is called the protocerebral clypeolabral segment. The segment itself has disappeared but its appendages remain as the clypeolabrum. The second preoral (antennal/deutocerebral) segment bears the antennae which are therefore true segmental appendages. The third preoral (intercalary/tritocerebral) segment appears briefly during embryogenesis, then is lost. Its appendages, however, remain as part of the hypopharynx (Kukalova´-Peck, 1992). Head segments 4–6 are post-oral and named the mandibular maxillary, and labial, respectively. Their appendages form the mouthparts from which their names are derived. In addition, the sternum of the mandibular segment becomes part of the hypopharynx.<br /><br />General Structure<br /><br />Primitively the head is oriented so that the mouthparts lie ventrally (the hypognathous condition) (Figure 3.3B). In some insects, especially those that pursue their prey or use their mouthparts in burrowing, the head is prognathous in which the mouthparts are directed anteriorly (Figure 3.4A). In many Hemiptera the suctorial mouthparts are posteroventral in position (Figure 3.4B), a condition described as opisthognathous (opisthorhynchous).<br />The head takes the form of a heavily sclerotized capsule, and only the presence of the antennae and mouthparts provides any external indication of its segmental construction. In most adult insects and juvenile exopterygotes a pair of compound eyes is situated dorsolater- ally on the cranium, with three ocelli between them on the anterior face (Figure 3.3A). The two posterior ocelli are somewhat lateral in position; the third ocellus is anterior and median. The antennae vary in location from a point close to the mandibles to a more median position between the compound eyes. On the posterior surface of the head capsule is an aperture, the occipital foramen, which leads into the neck. Of the mouthparts, the labrum hangs down from the ventral edge of the clypeus, the labium lies below the occipital foramen, and the paired mandibles and maxillae occupy ventrolateral positions (Figure 3.3B). The mouth is situated behind the base of the labrum. The true ventral surface of the head capsule is the hypopharynx (Figure 3.3D), a membranous lobe that lies in the preoral cavity formed by the ventrally projecting mouthparts.<br />There are several grooves and pits on the head (Figure 3.3A–C), some of which, by virtue of their constancy of position within a particular insect group, constitute important taxonomic features. The grooves are almost all sulci. The postoccipital sulcus separates the maxillary and labial segments and internally forms a strong ridge to which are attached the muscles used in moving the head and from which the posterior arms of the tentorium arise (see following paragraph). The points of formation of these arms are seen externally as deep pits in the postoccipital groove, the posterior tentorial pits The epicranial suture is a line of weakness occupying a median dorsal position on the head. It is also known as the ecdysial line, for it is along this groove that the cuticle splits during ecdysis. In many insects the epicranial suture is in the shape of an inverted Y whose arms diverge above the median ocellus and pass ventrally over the anterior part of the head. The occipital sulcus which is commonly found in orthopteroid insects, runs transversely across the posterior part of the cranium. Internally it forms a ridge that strengthens this region of the head. The subgenal sulcus isa lateral groove in the cranial wall running slightly above the mouthpart articulations. That part of the subgenal sulcus lying directly above the mandible is known as the pleurostomal sulcus; that part lying behind is the hypostomal sulcus, which is usually continuous with the postoccipital suture. In many insects the pleurostomal sulcus is contin- ued across the front of the cranium (above the labrum), where it is known as the Epistomal ( frontoclypeal) sulcus. thin this sulcus lie the anterior tentorial pits, which indicate the internal origin of the anterior tentorial arms. The antennal and ocular sulci indicate internal cuticular ridges bracing the antennae and compound eyes, respectively. A subocular sulcus running dorsolaterally beneath the compound eye is often present.<br /> The tentorium (Figure 3.5) is an internal, cranial-supporting structure whose morphology varies considerably among different insect groups. Like the furca of the thoracic segments (Section 4.2), with which it is homologous, it is produced by invagination of the exoskeleton. Generally, it is composed of the anterior and posterior tentorial arms that may meet and fuse within the head. Frequently, additional supports in the form of dorsal arms are found. The latter are secondary outgrowths of the anterior arms and not apodemes. The junction of the anterior and posterior arms is often enlarged and known as the tentorial bridge corporotentorium In addition to bracing the cranium, the tentorium is also a site for the insertion of muscles controlling movement of the mandibles, maxillae, labium, and hypopharynx.<br />The grooves described above delimit particular areas of the cranium that are useful in descriptive or taxonomic work. The major areas are as follows. The frontoclypeal area is the facial area of the head, between the antennae and the labrum. When the epistomal sulcus is present, the area becomes divided into the dorsal frons and the ventral clypeus. The latter is often divided into a postclypeus and an anteclypeus The vertex is the dorsal surface of the head. It is usually delimited anteriorly by the arms of the epicranial suture and posteriorly by the occipital sulcus. The vertex extends laterally to merge with the gena, whose anterior, posterior, and ventral limits are the subocular, occipital, and subgenal sulci, respectively. The horseshoe-shaped area lying between the occipital sulcus and postoccipital sulcus is generally divided into the dorsal occiput, which merges laterally with the postgenae. The postocciput is the narrow posterior rim of the cranium surrounding the occipital foramen.<br />It bears a pair of occipital condyles to which the anterior cervical sclerites are articulated. Below the gena is a narrow area, the subgena, on which the mandible and maxilla are articulated. The labium is usually articulated directly with the neck membrane (Figure 3.3C), but in some insects a sclerotized region separates the two. This sclerotized area develops in one of three ways: as extensions of the subgenae which fuse in the midline to form a subgenal bridge, as extensions of the hypostomal areas to form a hypostomal bridge, or(in most prognathous heads) through the extension ventrally and anteriorly of a ventral cervical sclerite to form the gula. At the same time the basal segment of the labium may also become elongated (Figure 3.4A).<br /><br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTteFME86QgGdA-dGbZRWfrnnUrOlPGwlOidyrH3YeUSP6CouDRS57W7uFIUMSnKebrVtaPeCVklUT3QPzVhfimSIbp8PZ4w2TWqoHplwMkz2pFQnZnkEr0QpndkeZQsOStW2J6rEf2n8/s1600/image1.bmp"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 300px; height: 320px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTteFME86QgGdA-dGbZRWfrnnUrOlPGwlOidyrH3YeUSP6CouDRS57W7uFIUMSnKebrVtaPeCVklUT3QPzVhfimSIbp8PZ4w2TWqoHplwMkz2pFQnZnkEr0QpndkeZQsOStW2J6rEf2n8/s320/image1.bmp" alt="" id="BLOGGER_PHOTO_ID_5512469574768464642" border="0" /></a><br /><br />FIGURE 3.3. Structure of the typical pterygotan head. (A) Anterior; (B) lateral; (C) posterior; and (D) ventral<br />(appendages removed). [From R. E. Snodgrass. Principles of Insect Morphology. Copyright 1935 by McGraw-Hill, Inc. Used with permission of McGraw-Hill Book Company.]<br /><br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggrO4OnbHmOc6YUYOgGaooMDbXlGHDb-VNWm0-YUoAQUEQBWi6M5B4efxEH41B_pYVmqWSJGi0oqbw_gSj2oFbL4j_aiWfYqJYxS4cI88rXUYV3D2fwlQdoL3HjWj7prKZu-L0uB21rAU/s1600/image2.bmp"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 234px; height: 320px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggrO4OnbHmOc6YUYOgGaooMDbXlGHDb-VNWm0-YUoAQUEQBWi6M5B4efxEH41B_pYVmqWSJGi0oqbw_gSj2oFbL4j_aiWfYqJYxS4cI88rXUYV3D2fwlQdoL3HjWj7prKZu-L0uB21rAU/s320/image2.bmp" alt="" id="BLOGGER_PHOTO_ID_5512469826830100114" border="0" /></a><br /><br /><br />FIGURE 3.4. (A) Prognathous; and (B) opisthognathous types of head structure. [A, from R. E. Snodgrass, Principles of Insect Morphology Copyright 1935 by McGraw-Hill, Inc. Used with permission of McGraw-Hill Book Company. B, after R. F. Chapman, 1971, The Insects: Structure and Function By permission of Elsevier North-Holland, Inc., and the author.]<br /><br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgj0lcO5ecqFoqqG7nFWovoDRZhpA4GoYqADWXtZBapwubXxF8RTVN8cIDyqHns_kjUNLeVGtAqIy1h85uNN5XIzbWErO-BYfG_RGgS7GHfU2OhWll4WwmJS1IvsmN23G7IktWcFz96U7U/s1600/image3.bmp"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 320px; height: 245px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgj0lcO5ecqFoqqG7nFWovoDRZhpA4GoYqADWXtZBapwubXxF8RTVN8cIDyqHns_kjUNLeVGtAqIy1h85uNN5XIzbWErO-BYfG_RGgS7GHfU2OhWll4WwmJS1IvsmN23G7IktWcFz96U7U/s320/image3.bmp" alt="" id="BLOGGER_PHOTO_ID_5512470177579834962" border="0" /></a><br /><br />FIGURE 3.5. Relationship of the tentorium to grooves and pits on the head. Most of the head capsule has been cut away. [From R. E. Snodgrass. Principles of Insect Morphology Copyright 1935 by McGraw-Hill, Inc. Used with permission of McGraw-Hill Book Company.]DR. LAXMIKANT B. DAMAhttp://www.blogger.com/profile/13198225293462944168noreply@blogger.com5tag:blogger.com,1999:blog-4764725322678313110.post-82246266212762778532010-09-02T16:41:00.000-07:002021-11-06T19:09:20.758-07:00The Head<br /><br />The head, being the anterior tagma, bears the major sense organs and the mouthparts. Considerable controversy still surrounds the problem of segmentation of the insect head, especially concerning the number and nature of segments anterior to the mouth. At various times it has been argued that there are from three to seven segments in the insect head, though it is now widely agreed that there are six. <br /><br />The embryological studies have demonstrated convincingly that an acron is present. However, it is never seen in fossil insects or other arthropods because it moved dorsally to merge imperceptibly into the region between the compound eyes. Both embryology and paleontology have confirmed that there are three preoral and three postoral segments The first preoral segment is preantennal; it is called the protocerebral clypeolabral segment. The segment itself has disappeared but its appendages remain as the clypeolabrum. The second preoral (antennal/deutocerebral) segment bears the antennae which are therefore true segmental appendages. The third preoral (intercalary/tritocerebral) segment appears briefly during embryogenesis, then is lost. Its appendages, however, remain as part of the hypopharynx (Kukalova´-Peck, 1992). Head segments 4–6 are post-oral and named the mandibular maxillary, and labial, respectively. Their appendages form the mouthparts from which their names are derived. In addition, the sternum of the mandibular segment becomes part of the hypopharynx.<br /><br />General Structure<br /><br />Primitively the head is oriented so that the mouthparts lie ventrally (the hypognathous condition) (Figure 3.3B). In some insects, especially those that pursue their prey or use their mouthparts in burrowing, the head is prognathous in which the mouthparts are directed anteriorly (Figure 3.4A). In many Hemiptera the suctorial mouthparts are posteroventral in position (Figure 3.4B), a condition described as opisthognathous (opisthorhynchous).<br />The head takes the form of a heavily sclerotized capsule, and only the presence of the antennae and mouthparts provides any external indication of its segmental construction. In most adult insects and juvenile exopterygotes a pair of compound eyes is situated dorsolater- ally on the cranium, with three ocelli between them on the anterior face (Figure 3.3A). The two posterior ocelli are somewhat lateral in position; the third ocellus is anterior and median. The antennae vary in location from a point close to the mandibles to a more median position between the compound eyes. On the posterior surface of the head capsule is an aperture, the occipital foramen, which leads into the neck. Of the mouthparts, the labrum hangs down from the ventral edge of the clypeus, the labium lies below the occipital foramen, and the paired mandibles and maxillae occupy ventrolateral positions (Figure 3.3B). The mouth is situated behind the base of the labrum. The true ventral surface of the head capsule is the hypopharynx (Figure 3.3D), a membranous lobe that lies in the preoral cavity formed by the ventrally projecting mouthparts.<br />There are several grooves and pits on the head (Figure 3.3A–C), some of which, by virtue of their constancy of position within a particular insect group, constitute important taxonomic features. The grooves are almost all sulci. The postoccipital sulcus separates the maxillary and labial segments and internally forms a strong ridge to which are attached the muscles used in moving the head and from which the posterior arms of the tentorium arise (see following paragraph). The points of formation of these arms are seen externally as deep pits in the postoccipital groove, the posterior tentorial pits The epicranial suture is a line of weakness occupying a median dorsal position on the head. It is also known as the ecdysial line, for it is along this groove that the cuticle splits during ecdysis. In many insects the epicranial suture is in the shape of an inverted Y whose arms diverge above the median ocellus and pass ventrally over the anterior part of the head. The occipital sulcus which is commonly found in orthopteroid insects, runs transversely across the posterior part of the cranium. Internally it forms a ridge that strengthens this region of the head. The subgenal sulcus isa lateral groove in the cranial wall running slightly above the mouthpart articulations. That part of the subgenal sulcus lying directly above the mandible is known as the pleurostomal sulcus; that part lying behind is the hypostomal sulcus, which is usually continuous with the postoccipital suture. In many insects the pleurostomal sulcus is contin- ued across the front of the cranium (above the labrum), where it is known as the Epistomal ( frontoclypeal) sulcus. thin this sulcus lie the anterior tentorial pits, which indicate the internal origin of the anterior tentorial arms. The antennal and ocular sulci indicate internal cuticular ridges bracing the antennae and compound eyes, respectively. A subocular sulcus running dorsolaterally beneath the compound eye is often present.<br /> The tentorium (Figure 3.5) is an internal, cranial-supporting structure whose morphology varies considerably among different insect groups. Like the furca of the thoracic segments (Section 4.2), with which it is homologous, it is produced by invagination of the exoskeleton. Generally, it is composed of the anterior and posterior tentorial arms that may meet and fuse within the head. Frequently, additional supports in the form of dorsal arms are found. The latter are secondary outgrowths of the anterior arms and not apodemes. The junction of the anterior and posterior arms is often enlarged and known as the tentorial bridge corporotentorium In addition to bracing the cranium, the tentorium is also a site for the insertion of muscles controlling movement of the mandibles, maxillae, labium, and hypopharynx.<br />The grooves described above delimit particular areas of the cranium that are useful in descriptive or taxonomic work. The major areas are as follows. The frontoclypeal area is the facial area of the head, between the antennae and the labrum. When the epistomal sulcus is present, the area becomes divided into the dorsal frons and the ventral clypeus. The latter is often divided into a postclypeus and an anteclypeus The vertex is the dorsal surface of the head. It is usually delimited anteriorly by the arms of the epicranial suture and posteriorly by the occipital sulcus. The vertex extends laterally to merge with the gena, whose anterior, posterior, and ventral limits are the subocular, occipital, and subgenal sulci, respectively. The horseshoe-shaped area lying between the occipital sulcus and postoccipital sulcus is generally divided into the dorsal occiput, which merges laterally with the postgenae. The postocciput is the narrow posterior rim of the cranium surrounding the occipital foramen.<br />It bears a pair of occipital condyles to which the anterior cervical sclerites are articulated. Below the gena is a narrow area, the subgena, on which the mandible and maxilla are articulated. The labium is usually articulated directly with the neck membrane (Figure 3.3C), but in some insects a sclerotized region separates the two. This sclerotized area develops in one of three ways: as extensions of the subgenae which fuse in the midline to form a subgenal bridge, as extensions of the hypostomal areas to form a hypostomal bridge, or(in most prognathous heads) through the extension ventrally and anteriorly of a ventral cervical sclerite to form the gula. At the same time the basal segment of the labium may also become elongated (Figure 3.4A).<br /><br /><br /> <br /><br />FIGURE 3.3. Structure of the typical pterygotan head. (A) Anterior; (B) lateral; (C) posterior; and (D) ventral<br />(appendages removed). [From R. E. Snodgrass. Principles of Insect Morphology. Copyright 1935 by McGraw-Hill, Inc. Used with permission of McGraw-Hill Book Company.]<br /><br /><br /><br /> <br /><br />FIGURE 3.4. (A) Prognathous; and (B) opisthognathous types of head structure. [A, from R. E. Snodgrass, Principles of Insect Morphology Copyright 1935 by McGraw-Hill, Inc. Used with permission of McGraw-Hill Book Company. B, after R. F. Chapman, 1971, The Insects: Structure and Function By permission of Elsevier North-Holland, Inc., and the author.]<br /><br /><br /><br /><br /> <br /><br />FIGURE 3.5. Relationship of the tentorium to grooves and pits on the head. Most of the head capsule has been cut away. [From R. E. Snodgrass. Principles of Insect Morphology Copyright 1935 by McGraw-Hill, Inc. Used with permission of McGraw-Hill Book Company.]<br />DR. LAXMIKANT B. DAMAhttp://www.blogger.com/profile/13198225293462944168noreply@blogger.com0tag:blogger.com,1999:blog-4764725322678313110.post-43938243866717850502010-08-08T19:34:00.000-07:002010-08-08T19:40:17.649-07:00Hi, welcomeHi,<br />Dear students,<br />This blog is created for you, All T.Y.B.Sc.Zoology specialization, Puna University Students who are learning Entomology.<br />Here I will post notes of Basic entomology ( new syllabus).<br />Also if you have any particular difficulty I will solve it here, lots of information on insect is available on the Internet, but to save your time i decided to post all sorted information here.<br />so join this post....tell your friends about this... spread information...<br />avoid papers...., be paper less........ save forest...... save earth....DR. LAXMIKANT B. DAMAhttp://www.blogger.com/profile/13198225293462944168noreply@blogger.com0