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Reproductive System in Insects
The reproductive systems of insects are similar to those of vertebrates, with both male and female gametes being haploid and unicellular. Most insect species reproduce sexually through internal fertilization. The male reproductive system produces and stores sperm in the testes and seminal vesicles before delivering it to the female through the aedeagus. The female system produces eggs in the ovaries which develop and move into the common oviduct for fertilization and laying. Accessory glands support these processes by providing fluids and forming the eggshell. Fertilization occurs when sperm fuses with the egg nucleus, and the fertilized egg then undergoes embryonic development.
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Reproductive System in Insects
- 1. Reproductive System inInsects. AEN 201 Fundamentals Of Entomology. Course Mentor: Dr Pretheep Kumar Expounded by: Chandini S 2013-009-005 II B.Sc.(Sericulture)
- 2. &The reproductive organsof 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 theReproductive System: Male: &Production of sperm. &Storage of sperm. &Delivery of sperms to the female. Female: &Production of eggs, including yolk and chorion formation. &Reception and storage of sperm (may be for long times). &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. &Spermatocytes - migratetoward 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. &2 major functions of accessory glands: Manufacture of seminal fluid. Production of spermatophores.
- 6. &Mature sperm passout of the testes through short ducts – Vasa efferentia. &Collected in storage chambers – Seminal vesicles. &Similar ducts – Vasa deferentia – from the seminal vesicles – join together near the body mid line – form a single Ejaculatory duct – leads out of the body through copulatory organ – Aedeagus.
- 8. Female Reproductive System: &Apair 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. &Each oocyte – undergoes Meiosis – yields 4 cells – 1 egg and 3 polar bodies.
- 9. &Polar bodies maydisintegrate 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. &Near the body midline – lateral oviducts join to form a common oviduct – opens into a genital chamber – Bursa Copultrix. &Female accessory glands – supply lubricants for the reproductive system and screte a protein-rich egg shell – Chorion. &Accessory glands – usually connected by small ducts to the common oviduct – Bursa Copultrix.
- 11. Processes: &Copulation – Themale deposits its spermatophore in the bursa copultrix. &Peristaltic contractions force the spermatophore into the female’s spermatheca. &Spermathecal gland – 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.
- 12. &Fertilization – Occursas soon as one sperm’s nucleus fuses with the egg cell’s nucleus. &Oviposition – Egg laying – usually follows closely after fertilization. &After the completion of all the processes – the egg is ready to begin embryonic development.
- 13. Oviparity: &Egg laid shortlyafter fertilization. &No retention &No nutrients to embryo after fertilization. &Eggs retained. &Embryo fed by mother. &Immature may complete development before deposition. Viviparity:
- 14. Types of Reproduction: &Paedogenesis – Reproduction by larval insects. & Parthenogenesis – Developments without fertilization – Unfertilized eggs produce – Males, Female, Or Both. & Polyembryony . Mating: & Females of some species – essentially Monogamous – mate only once. & Most female insects – Polygamous - mate several to many times.
- 15. CITATION: “The Reproductive Systemof Insects” Dr Arwa Elaagip, Department of Parasitology and Medical Entomology, University of Kartoum.
- 16.
Editor's Notes
- #5 Seminal fluid- a liquid medium that sustains and nourishes mature sperm while they are in the males’s genital system. Speramtophores- pouch like structures(mostly ptn) that encase the sperm and protect them as they are delivered to the female’s body during copulation.
- #12 Enzymes for digesting the protein coat of the spermatophore. Nurtrients for sustaining the sperm while they are in storage. A sperm may live in spermatheca for weeks, months or even years!