Parasitoids modify their oviposition behavior according to the sexual origin of conspecific cuticular hydrocarbon traces.

Hydrocarbons play a crucial role in insect behavior in general and in sexual recognition in particular. Parasitoids often modify their oviposition behavior according to hydrocarbons left by conspecifics on the reproductive patch, such as oviposition markers left by females after oviposition, or cuticular hydrocarbon (CHC) traces left by individuals by walking or rubbing. This study determined whether Eupelmus vuilleti females are able to distinguish CHCs left by male or female conspecifics on seeds. The results show that the cuticular profile of E. vuilleti differs according to its gender, and that females are able to detect the sexual origin of these CHCs. Moreover, they adjust their oviposition behavior according to the nature of these traces. Although females lay fewer eggs on hosts when confronted with female CHCs, they lay more daughters when confronted with male CHCs, thus changing the sex ratio.