The role of semiochemicals in host location by the parasitoid Pteromalus cerealellae (Boucek) was investigated in Y-tube and three-way olfactometers, by measuring responses to stimuli associated with the cowpea weevil, Callosobruchus maculatus. Orientation of mated parasitoid females was measured in response to five stimuli: live virgin female bruchid beetles, solvent extracts of whole body virgin female bruchids, solvent extracts of the oviposition marking pheromone from a glass substrate, previously infested cowpea seeds with adult emergence holes, and uninfested cowpea seeds. All stimuli elicited significantly better responses than those to blank controls. Female parasitoids that had previous exposure to live, virgin beetles and infested seeds exhibited shorter latency and response times to the stimuli than did naïve females. Live, virgin female bruchids and whole body solvent extracts of virgin female bruchids elicited the strongest responses. Comparison of responses in a three-way olfactometer of whole body solvent extracts of virgin female bruchids, infested seeds, and solvent extracts of bruchid oviposition marker pheromone showed that whole body extracts of virgin female bruchids elicited the strongest response by both host-experienced and naïve female parasitoids. The potential for innate responses to host-specific chemical cues and the possibility of female parasitoids using chemical cues from adult hosts are discussed.
Annals of the Entomological Society of America
Vol. 97 • No. 2
Vol. 97 • No. 2