Genetic variation in behavioral response to herbivore-infested plants in the parasitic wasp, Cotesia glomerata (L.) (Hymenoptera : Braconidae)

Female Cotesia glomerata (L.) relies on stimuli front herbivore-infested pl ants to select suitable hosts, but behavioral response to such stimuli is h ighly variable among individuals. This study investigates a genetic compone nt of phenotypic variability in both short-range host-search and long-range host-location behaviors in the tritrophic system consisting of cabbage pla nts (Brassica oleracea L.), cabbage butterfly (Pieris brassicae L.) and the parasitoid, by comparing full-sib families established from a laboratory p opulation and isofemale strains from a field population. Short-range host-s earch behaviors were examined within a Petri-dish test arena and long-range host-location behaviors assessed in a wind tunnel. Significant differences among full-sib families were shown in the duration of walking on a plant-h erbivore complex (i.e., a leafsection with two host caterpillars, their sil k and feces) and searching off the complex, and the total time elapsed for wasps to locate a host larva after release into the test arena. Flight resp onses to and landing choices between the intact and the herbivore-infested plants were also significantly different among these families. Effects of f amilies on both short-range hostsearch and long-range host-location behavio rs were consistent, without significant influences of host larvae from whic h wasps emerged. The analysis of isofemale strains reveals that strains acc ount for significant variation in the oriented flight response to herbivore -infested plants, and the "isofemale heritability" for this behavioral char acter is estimated as 0.447. The results suggest that genetic variation exi sts nt different behavioral levels of the host-selection process in this pa rasitoid.