Abstract
In pheromone extracts of calling female Chiasma clathrata L. (Lepidoptera: Geometridae), a defoliator pest of alfalfa, (Z,Z,Z)-3,6,9-heptadecatriene and (Z,Z)-6,9-cis-3,4-epoxyheptadecadiene was identified. Chiral gas chromatography using a modified cyclodextrin and synthetic reference samples proved the natural epoxide to show (3 R,4S)-configuration. In field trapping tests, only the pure (3 R,4S)-enantiomer of the epoxide attracted males. The addition of the triene component was synergistic. Males of the sympatric species Tephrina arenacearia Hbn. (Lepidoptera:Geometridae) were caught only in traps with baits containing the (3S,4R)-enantiomer [together with a previously described minor component, (Z,Z)-3,9-cis-6,7-epoxyheptadecadiene]. In trapping tests conducted in a different biotope, Abraxas grossu-lariata L. (Lepidoptera: Geometridae) males were attracted by the (SS,4R)-enantiomer, whereas the (3R,4S)-enantiomer attracted a close relative Abraxas sylvata Scop. (Lepidoptera:Geometridae). The present results suggest that one of the key mechanisms responsible for pheromone specificity among both the two alfalfa geometrids and the two Abraxas species in their respective biotops, may be the use of different enantiomers of the same polyene-derived epoxide as a sex pheromone component. It is probable that this discrimination mechanism is widespread among moth species utilizing epoxide pheromone components.
