Insect Internal Anatomy

Question 1

How does btk work?

Answer 1

Targets insects midgut to disrupt digestion resulting in imminent death.

Question 2

Describe the basic internal anatomy of insects?

Answer 2

Digestive system: structure correlates with function.**

Morphological, biochemical and physiological modifications reflect food eaten

• Alimentary canal consists of 3 main regions:
• Foregut (ingestion, grinding and transport of food)
• Midgut (production and secretion of digestion enzymes and absorption of food)
• Hindgut (reabsorption of water and salts. excess expelled in feces) similar to humans

Question 3

What are nitrogen wastes excreted from?

Answer 3

Malphigian tubules.

Question 4

How do insects breathe?

Answer 4

Tracheal tube system takes in oxygen and excretes carbon dioxide.

Question 5

What is the function of the salivary glands?

Answer 5

Produce saliva with diverse functions depending on diet and lifestyle:

• Lubricant producing digestive enzymes
• Anticoagulant (e.g. mosquito)
• Toxin (e.g. carnivores)
• Antibiotic properties (e.g. ants, termites) protection of pupa and colony.
• Necrotic (e.g. herbivores) enzymes that break down plants
• Nest construction (social insects)
• Insect saliva also important from disease transmission perspective (e.g. Malaria, plant viruses)

Question 6

What is the insect foregut composed of ?

Answer 6

-Pharynx – muscular pump

• Esophagus (tube connecting mouth to crop)
• Crop (Food storage)
• Proventriculus (grinding gizzard)

All of these modified depending on diet.

Question 7

What are the functions and parts in the midgut?

Answer 7

Two main regions function in digestion and absorption** crucial in all insect pests.

• Ventriculus (stomach) digestion by enzymes
• Gastric cecae (increased surface area for absorption of food)

Question 8

How does structure relate to function of midgut?

Answer 8

• Midgut epithelium ultrastructure complex – cells loaded with mitochondria and endoplasmic reticulum (build protein) and microvilli (increased S.A.)
• Midgut is the major site for complex biochemical and enzymatic interactions

Question 9

How are nutrients transported? How are cellular functions powered?

Answer 9

Through the hemolymph. Cellular functions and nutrient transport powered by mitochondria.

Question 10

What are the main functions of the Hindgut?

Where does it start?

Answer 10

Functions are osmoregulation, excretion and reabsorption.
Landmark for beginning of hindgut are Malpighian tubules (basic kidneys)

• Hindgut - m. tubules play huge roles in regulation of water, conservation and salt balance of hemolymph (osmoregulation)
• Anterior intestine (colon): posterior muscular rectum for reabsorption of water and salts as well as excretion.

Question 11

Give all the functions of the Malpighian tubules

Answer 11

• Malpighian tubules – slender convoluted tubes bathing the hemolymph
• Function to maintain homeostasis:
• Remove excess water from hemolymph
• Excretion of nitrogenous wastes (uric acid)
• Ionic regulation (esp. sodium, potassium, calcium)
• MT work in conjunction with rectum – reabsorption of needed substances (e.g. water, amino acids, ions)
• Huge variety of MT - rectal cycling osmoregulatory systems depending on insect’s

Question 12

How is the insect digestive system inter related?

Answer 12

PTQ*** long answer