Learning of host-infested plant volatiles in the larval parasitoid Cotesia kariyai

The ability to learn plant volatiles in Cotesia kariyai females was examined by wind tunnel bioassays. Searching experience on a host-infested corn plant increased subsequent flight responses of females to the infested plant. Females experiencing host by-products together with the volatiles extracted from infested leaves one time showed an increased response. However, such behavioral changes were not observed in females which experienced only the host by-products or the volatiles. Thus, the increased response is considered to be preference learning. Multiple experiences of C. kariyai with host by-products together with the volatiles did not increase their flight response to the volatiles. Furthermore, this learned response gradually decreased within 2 days. These behavioral modifications based on experience would be advantageous for C. kariyai to locate their polyphagous hosts efficiently.