ACOMPARATIVE STUDY ON THE ELECTROANTENOGRAM RESPONSES OF THREE APHID SPECIES TO PLANT VOLATILES

Abstract  Electroantennogram responses (EAGs) to 39 plant volatiles from Aphis glycines, A. gossypii and Myzus persicae were recorded. The olfactory system of these three aphid species differentially responded to green leaf, aromatic, mono-and sequiterpene chemicals. The EAG depolarizatin to green leaf chemicals and their isomers were more pronounced than to terpenes, alcohols and aldehydes, 6 carbon atom compounds being the most effective. It was shown that there was certain difference in the olfactory spectra of these three aphid species to plant volatiles. Higher responses in A. glycines and A. gossypii were elicited by the leaf aldehydes and esters than by the corresponding alcohols, which are in contrast with those in M. persicue . The activity of aphid olfactory system was related to molecular structures of the compounds. The responses to saturated alcohols and aldehydes were higher than those to unsaturated. The responses of spring emigrants of A. glycines to terpene derivatives (alcohols, aldehydes and esters) were higher than those of A. gossypii , but were lower to terpene hydrocarbons. The dissimilarity in olfactory spectra of the aphid species reflected the evolution of their host plant selection specificity. In the evolution, their chemosensory system adapted to perceive host plants. The shapes of the EAGs evoked by the various components were consistently different, with the slowest recovery for geraniol, 1-decanol and (±)-β-cit-ronellol, and ware related to number of carbon atoms in straight chain saturated alcohols.