external morphology, digestion and microscopic details.

1. INSECT
DIGESTIVE
SYSTEMS
Presented By:
M.Abdullah
Islamia University of
Bahawalpur

2. FOREGUT MIDGUT HINDGUT

3. pharynx
esophagus
crop
Malpighian tubulessalivary glands
cibarium
salivarium
gastric caeca
proventriculus
pylorus
ileum
rectum
ventriculus
anus

4. Variation in insect guts

5. What does the digestive system do?
1. Obtaining food
2. Mechanically breaks good down into smaller particles
that facilitate the activity of digestive enzymes.
3. Enzymatic breakdown of larger food molecules into
molecules that can enter the hemolymph.
4. Produce molecules that coordinate feeding and other
digestive activities

6. Salivary Glands

7. Functions of Salivary Glands
1. Moisten food
2. Lubricate mouthparts
3. Contains digestive enzymes
3a. Amylase – complex sugars to simple sugars
3b. Salivary enzymes for preoral digestion
4. Non-digestive functions
4a. Toxins of predators that affect CNS of prey
4b. Counter toxins of plant allelochemicals
4c. Anti-coagulants
4d. Silk production

8. Insect Saliva - Composition
e.g. Mosquito saliva
- 20 polypeptides
> 70 unique proteins

9. Salivary Glands
Aphid Blood feeders
Silk cocoons Plant galls

10. Foregut
Cicada (Homoptera)

11. pharynx
esophagus
crop
Malpighian tubulessalivary glands
cibarium
salivarium
gastric caeca
proventriculus
pylorus
ileum
rectum
ventriculus
anus

12. Peritrophic membrane
Secretion
Delamination

13. Peritrophic membrane
Peritrophic membrane
Bacterium
Food

14. Peritrophic membrane
Peritrophic membrane

15. Peritrophic membrane
Enclosing fecal
pellet
Peritrophic
membrane

16. pharynx
esophagus
crop
Malpighian tubulessalivary glands
cibarium
salivarium
gastric caeca
proventriculus
pylorus
ileum
rectum
ventriculus
anus

17. Midgut Enzymes -
Insect Diet Protease Lipase Amylase Invertas
e
Maltase
Cockroach omnivorous √ √ √ √ √
Carausius phytophagou
s
√ √ √ √ √
Lepidopter
a larvae
phytophagou
s
√ √ √ √ √
adults nectar √
adults Non-feeding
Lucilia meat √ √
Glossina blood √

18. Termites

19. Absorption of digested material

20. Absorption of digested material
Movement of H20
Movement of water, inorganic ions, sugars & amino acids
caecum
Malpighian
tubule

21. Fat Body
Functions of fat body
- metabolism of carbohydrates, lipids and nitrogenous compounds
- storage of glycogen, fat and protein
- regulation of blood sugar
-synthesis of major hemolymph (blood) proteins
(haemoglobins, vitellogenins, storage proteins)

22. Fat Body
Functions of fat body – changes with needs – e.g. calliphorin
10
5
0
Amountofcalliphorininhemoglobin
~7
~3
~.03

23. Fat Body – cell types
Trophocytes
-carry out most of
functions of fat body
Urocytes
- storage of urates/uric acid