The document details the insect digestive system, which consists of three main parts: the foregut, midgut, and hindgut, and includes the structure and function of salivary glands. It discusses the composition of saliva, types of salivary glands, and their roles in digestion, such as enzyme secretion and food lubrication. Additionally, it explains the regulation of these processes by the nervous system and neurohormones.

1. INSECT
DIGESTIVE
SYSTEM

2. FOREGUT MIDGUT HINDGUT
Insect digestive system
1. Foregut (stomodeum) - ectodermal
2. Hindgut (proctodeum) - ectodermal
3. Midgut (mesenteron) - endodermal

3. Index
• Alimentary canal
1. Foregut
2. Midgut
3. Hindgut
• Salivary glands
1. Types
2. Composition of Saliva
3. Regulation
4. Functions of salivary glands

4. pharynx
esophagus
crop
Malpighian tubulessalivary glands
mouth
salivarium
Hepatic caeca
gizzard
pylorus
ileum
rectum
ventriculus
anus
FOREGUT MIDGUT HINDGUT

5. Peritrophic membrane
Type 1
Type 2

6. Salivary Glands
salivary glands
salivarium

7. Two types
1. Acinar – multicellular with sac-like units
-Regulated by CNS
-Eg-Orthoptera

8. 2. Tubular – Regulated by serotonin from hemolymph.
-Eg- Diptera , Lepidoptera , Hymenoptera

9. Composition
• Depends on diet of insect.
• Consist of-
1. Amylase-Starch to Maltose
2. Invertase-Sucrose to Glucose and fructose
3. Lipase-Fat to fatty acid and glycerol
4. Pectinase
5. Hyaluronidase
6. Antihaemostatic agent

10. Subesophageal
ganglion
Stomatogastric NS
Regulation
1. By stomatogastric nervous system and subesophagal
ganglion
2. Neurohormone

11. Functions of Salivary Glands
1. Moisten food
2. Lubricate mouthparts
3. Contains digestive enzymes
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