Postemergence learning in the insect parasitoid,Cotesia congregata (Say) (Hymenoptera: Braconidae)

Exposing newly emerged females of Cotesia congregata(Say) to wild cherry, an inherently unattractive plant, and their host larvae at 0–4 h after adult emergence induced a positive searching response to wild cherry and an inhibited response to cabbage, an attractive plant. Inherent responses were not affected when females were exposed to their hosts at 0–12 h and to cherry at 8–12 h after emergence. The induced response to cherry was constant until its disappearance at 6–7 days;inhibition of the response to cabbage was released at 4–5 days after emergence. Postemergence exposure to cherry and parasitoid cocoons induced similar but weaker searching responses. Induced searching responses exhibit features of associative learning and receptor modification. In addition to its presumed role in foraging, postemergence experience with plants may encourage assortative mating of C. congregatawithin suitable host habitats and, thus, facilitate local adaptations to specific plants.