Single Sensillum responses in the male moth Adoxophyes orana (F.v.R.) to female sex pheromone components and their geometrical isomers

A technique is described for the recording of receptor and action potentials from the outer dendritic segments of the olfactory cells in individual antennalSensilla trichodea in insects. The 50 μm long olfactory hairs on the antennae of adult male summerfruit toftrix moth,Adoxophyes orana, are shown to possess two cells responsive to the female sex pheromone (a 9∶1 mixture ofcis-9 andcis-11-TDA (= tetradecen-1-ol acetate)). One of these cells (typeB) is sensitive tocis-9-TDA, the other (type A) mainly responds tocis-11-TDA and, to a much smaller extent, tocis-9-TDA. The behavioural inhibitorstrans-9 andtrans-11-TDA evoke small responses in both cells, which may have been caused by contamination of these substances by thecis isomers (Fig. 6). It appears that the pheromone receptor cells are not ‘tuned’ to the optimal 9∶1 mixture (Fig. 7). Hence, the attractiveness of the pheromone should be determined in the central nervous system by comparison of the responses from theA andB cells. A rough calculation indicates that the males are very well able to discriminate between different mixture ratios. It is suggested that thecis-9-/cis-11-TDA ratio excreted by the females shows a considerable variation