3. • Insect are member of one of the biggest classes and phylum
arthopoda ( non chordates) with jointed legs.
• Body divided into head, thorax and abdomen.
Insect :-
4. General characters:-
• Triploblastic coelomate with bilateral symmetry.
• Segmented body aned jointed appendag.
• Exoskeleton.
• Lomotary system with skeleton muscles.
• 3 pair of peristomal appendages.
• Sense organ,antennae and coumpound eyes.
6. Abdomen :-
• An insect’s abdomen is third function region(tagma) of it’s
body .
• The abdomen is located is just behind the thorax.
• It consist of sclerotized, tergum and sternum.
• They jointed by membranous pleural region which are
commonly hidden beneath the sides of the tergum
7. • There is no sclerotization and the abdomen consist of serious
of membranous segments. This is true in many diptera,
coleoptera and hymenoptera
• The tergum sternum and pleural element sometimes fuse to
form a complete sclerotized ring this is in ephemeroptera and
dermaptera.
• In acrididae terga of segments 9 and 10 fuse together
• In some coleoptera the second sternum fuse with the next two
and the sutures between them are largely obliterated.
8. • The reproductive opening of male insect is usually on segment 9 .
• In females insect the opening of oviduct is on or behind segment 8
and 9.
•
9. Abdominal structure:-
• Spiracle :- opening of the respiratory system near the pleural
membrane on each side of the first eight abdomen.
• Anus :- rear opening to the respiratory system is present between
three protective sclerites.
• Cerci :- the pair of sensory organ located near the anterior margin
of paratop.
• Clasper :- the external genitalia may also include other sclerites.
10. Other abdominal structure
• Pincers :- the cerci are heavily sclerotized and foreceps. They are
used mostly for defense and sometimes to help in folding the
wing. ex- dermaptera.
• Median caudal filament :- a thread like projection arising
between the cerci. Ex- diplura, thysanura.
• Cornicles :- paired secretory structure located dorsally on the
abdomen of aphids. They produces substance that repel
predators or care-giving behavior by symbiotics ants.
11. • Abdomen proleg :- flesy locomotary appendages found only in
the larvae of certain order.
• Sting :- a modified ovipositor, found only in females of aculeate
hymenoptera.
• Abdominal gills :- respiratory organ found in the
nymphs(naiads) of certain aquatic insect.
12. • Furcula :- jumping organ. In springtail found in collembolan
on the ventral side of the fifth abdominal segment.
• Collophore :- a flesy peg like str. Found in collembola on the
ventral side of first abdominal segment. It appears to maintain
homeostasis by regulation of water from the environment.
