The long-term goal of this research is to elucidate the roles played by plant chemistry in the ecology and evolution of a single taxon of herbivorous insects, namely the butterfly family Papilionidae. Emphasis is placed on the chemical basis of plant recognition by ovipositing females. Identification of contact oviposition stimulants for the black swallowtail, Papilio polyxenes (tribe Papilionini), will be extended from carrot, Daucus carota, to other umbelliferous plants to assess the specificity of chemical response profiles in one insect species. Identification of contact stimulants will also be carried out with two subspecies of a close relative, P. machaon, which show apparent steps in a host switch from the Apiaceae to the Asteraceae (genus Artemisia). Identification of contact stimulants from Aristolochia species for Battus philenor, a more distant relative (tribe Troidini), will be completed and followed by similar studies with Eurytides marcellus, an Asimina-feeding species belonging to yet a third tribe (Graphiini). These comparative studies will permit testing of the long-held hypothesis that the adaptive radiation of swallowtail butterflies has been constrained by preadaptation to particular chemical compounds that are used as behavioral cues in host recognition.
