The chemical ecology of the lesser chestnut weevil : behavioral and electrophysiological responses of Curculio sayi (Coleoptera: curculionidae) to host-plant volatile organic compounds

Abstract

The most abundant volatile organic compounds (VOC) from chestnut reproductive plant tissue (catkin, nut and bur) were identified with gas chromatography and mass-spectrometry (GC-MS). Two-choice behavioral bioassays were conducted with a Y-tube olfactometer using chestnut plant tissues (leaf, catkin, nut and bur) and individual VOC to assess the response of adult lesser chestnut weevil, Curculio sayi. Additionally, the electrophysiological response of the antennae of C. sayi adults towards both plant tissue and individual VOC from chestnut was examined using an electroantennogram (EAG). The behavioral bioassay and EAG data associated with chestnut plant tissue demonstrated that the insect does not respond directly to the sites of oviposition (nut tissue), but rather more strongly to the spiked bur encasing the nuts, the leaves, and the spring florescence (catkins). There were several differences between male and female responses to plant tissue and individual VOC, as well as significant differences between those insects collected in the spring compared to those from the fall season. A qualitative analysis of the reproductive organs of C. sayi adults revealed distinct differences in their development across the spring and fall seasons for both males and females.