Reproductive System of Insects

2. Reproductive System of Insects: • The reproductive organs of insects are similar in structure and function to those of vertebrates. • Both types of gametes are haploid and unicellular, but eggs are usually much larger in volume than sperm. • Most insect species reproduce sexually by internal fertilization.

3. Functions of the Reproductive System: Male Female • Production of sperm. • Storage of sperm. • Delivery of sperms to the female • &Production of eggs, including yolk and chorion formation. • Reception and storage of sperm. • Coordination of events that lead to fertilization and oviposition.

4. Male Reproductive System • Testes - Usually near the back of the abdomen. • Each testes is subdivide into functional units - Follicles - sperm is produced. • At the distal end of each follicle-group of germ cells - Spermatogonia. • Spermatogonia- divide by mitosis - Increase in size to form Spermatocytes.

5. Male Reproductive System • Spermatocytes - migrate toward the basal end of the follicle. • Spermatocytes– undergo meiosis – yields 4 haploid spermatids. • Spermatids– develop into mature spermatozoa. • One or more pair of accessory glands – usually associated with male’s reproductive system.

6. Male Reproductive System

7. Female Reproductive System • A pair of ovaries. • Each ovary - subdivided into functional units – Ovarioles – Eggs are produced. • Near the distal end of each ovariole – group of germ cells – Oogonia – divide by Mitosis. • Oogonia– increase in size to form Oocytes.

8. Female Reproductive System • Each oocyte – undergoes Meiosis – yields 4 cells – 1 egg and 3 polar bodies. • Polar bodies may disintegrate or they may accompany the egg as nurse cells. • Developing eggs move down the ovariole – grow in size by absorbing yolk. • Mature eggs leave the ovaries through short Lateral Oviducts.

9. Female Reproductive System

10. Processes • Copulation – The male deposits its spermatophore in the bursa copultrix. • Peristaltic contractions force the spermatophore into the female’s spermatheca. • Spermathecalgland – Produces enzymes and nutrients. • Ovulation – Each egg passes across the opening to the spermatheca – stimulates release of a few sperm onto the egg’s surface.

11. Reproductive System in Insects Oviparity: Viviparity: • Egg laid shortly after fertilization. • No retention • No nutrients to embryo after fertilization. • Eggs retained. • Embryo fed by mother. • Immaturemay complete development before deposition.