Cotesia congregata
| Cotesia congregata | |
|---|---|
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| Parasitic wasp Cotesia congregata on hornworm Manduca sexta | |
| Male C. congregata courtship song | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hymenoptera |
| Family: | Braconidae |
| Genus: | Cotesia |
| Species: | C. congregata |
| Binomial name | |
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Cotesia congregata (Say, 1836) |
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| Synonyms | |
Cotesia congregata is a parasitoid wasp of the genus Cotesia. The genus is particularly noted for its use of polydnaviruses. Parasitoids are distinct from true parasites in that a parasitoid will ultimately kill its host or otherwise sterilize it.
Adult wasps lay their eggs in tobacco hornworm (Manduca sexta) larvae in their 2nd or 3rd instar (each instar is a stage between moltings, i.e. the second instar is the life stage after the first molt and before the second molting) and at the same time injects symbiotic viruses into the hemocoel of the host along with some venom. The viruses knock down the internal defensive responses of the hornworm. The eggs hatch in the host hemocoel within two to three days and simultaneously release special cells from the egg's serosa. These special cells, called teratocytes, grow to become giant cells visible to the naked eye. The teratocytes secrete hormones which work in tandem with the virus and the wasp venom to arrest the development of the host. Following hatching in the caterpillar, the wasp larvae will undergo 2 molts inside the host caterpillar’s hemocoel and, after 12 to 16 days post oviposition, the 3rd instar wasp larvae will emerge from the caterpillar and spin cocoons from which the adult wasps fly about 4 to 8 days later.
This insect has the shortest flagellated spermatozoa in animals, being 6.6 µm long (nucleus and flagellum), 8800 times shorter than the longest ones (Drosophila bifurca).
An important aspect of the symbiotic polydnavirus is the fact that the virus does not and cannot replicate on its own- it does not contain the genes necessary to replicate itself. Instead, the genes that code for the virus are contained within the genome of the wasp. The wasp contains special cells called calyx cells within its ovary, which in females will produce the virion particles. Male wasps contain the viral sequence, but do not have the capacity to produce it. The proteins and genetic payload of the virus are produced by these cells, and the virions are assembled within the nucleus of these cells. As the female matures, the nuclear membrane will dissolve, followed by the cell membrane, releasing the virions and cell debris into the lumen of the oviduct. Phagocytic cells will clean up the debris, and the virions will be injected into the host along with eggs and venom upon oviposition.
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Wikipedia