PHEROMONAL PRODUCTION OF AND RESPONSE TO OPTICALLY-ACTIVE EPOXYDIENESIN SOME GEOMETRID MOTHS (LEPIDOPTERA, GEOMETRIDAE)

In pheromone extracts of calling female Chiasma clathrata L. (Lepidopt era: Geometridae), a defoliator pest of alfalfa, (Z,Z,Z)-3,6,9-heptade catriene and (Z,Z)-6,9-cis-3,4-epoxyheptadecadiene was identified. Chi ral gas chromatography using a modified cyclodextrin and synthetic ref erence samples proved the natural epoxide to show (3 R,4S)-configurati on. In field trapping tests, only the pure (3 R,4S)-enantiomer of the epoxide attracted males. The addition of the triene component was syne rgistic. Males of the sympatric species Tephrina arenacearia Hbn. (Lep idoptera:Geometridae) were caught only in traps with baits containing the (3S,4R)-enantiomer [together with a previously described minor com ponent, (Z,Z)-3,9-cis-6,7-epoxyheptadecadiene]. In trapping tests cond ucted in a different biotope, Abraxas grossu-lariata L. (Lepidoptera: Geometridae) males were attracted by the (SS,4R)-enantiomer, whereas t he (3R,4S)-enantiomer attracted a close relative Abraxas sylvata Scop. (Lepidoptera:Geometridae). The present results suggest that one of th e 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 e poxide pheromone components.