Detection of fruit- and flower-emitted volatiles by olfactory receptor neurons in the polyphagous fruit chafer Pachnoda marginata (Coleoptera : Cetoniinae)

Olfactory receptor neurons on the antennae of the African fruit chafer spec ies Pachnoda marginata (Coleoptera: Scarabaeidae) were examined through ext ensive use of gas chromatography linked with electrophysiological recording s from single olfactory receptor neurons. Contacted neurons were stimulated with a large number of extracted volatiles from 22 different fruits and wi th 64 synthetic plant compounds. Extracted fruit volatiles were identified using linked gas chromatography-mass spectrometry. In total, 48 different o dor compounds were found to elicit responses. Analysis of the response spec tra of the contacted neurons (n = 232) revealed the presence of 28 classes of receptor neurons. The neurons exhibited strong selectivity as well as hi gh sensitivity. Eleven of the identified classes were selectively activated by single compounds, while the remaining were activated by 2-6 compounds. Several receptor neurons that were activated by more than one compound resp onded to compounds sharing basic structural similarities. The results suppo rt the growing hypothesis that a significant proportion of plant-odor recep tor neurons in insects are highly sensitive and selective for single odors.