Thursday, January 10, 2013

Parasitoid nuptial gifts?

A Braconid, Alabagrus texanus, a male. I doubt any nuptial gifts are given in this species scramble-mating system. 

I found something yesterday that I think is really-cool. While browsing old copies of the journal Bulletin of Entomological Research, I stumbled across this quote, in reference to Bracon sp. (probably hancocki).

"Average life-span for mated females was 13.6 days, whereas virgin females lived for an average of 5.6 days."

Here's the catch: parasitoids are unreported (at least that I could find) to give "nuptial gifts" i.e. a resource given by male to female during courtship or copulation. Charles Godfray, in his book (bible), Parasitoids: Behavioral and Evolutionary Ecology, says "I know of no evidence of nutrient transfer during mating in parasitoids". Many other insects are known to (katydids, certain flies, etc.). This quote makes it seem like there could be some transfer of nutrients in the sperm (as the authors made no mention of courtship behavior).

Making the story more interesting, and believable, the authors state that the females copulated many times with the same male upon emergence, then began egg-laying a few days later. Multiple matings are rare in parasitoids, another indication that the female is likely gaining something else besides just sperm from the male.

An interesting observation, and one that probably could be examined, as Bracon is a fairly common genus.

Reference: Olaifa, J. I., & Akingbohungbe, A. E. (1982). Bionomics of Bracon ?hancocki (Wilkinson)(Hymenoptera: Braconidae), a Larval Parasite of Cydia Ptychora (Meyrick)(Lepidoptera: Tortricidae) in Nigeria. Bulletin of Entomological Research, 72(04), 567-572.

Godfray, HC. (1994) Parasitoids: Behavioral and evolutionary ecology. Princeton University Press. 

This is the same species in the photo above emerging from a Herpetogramma caterpillar, prior
to spinning its cocoon. 

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