REDUCTASE SPECIFICITY AND THE RATIO REGULATION OF E Z ISOMERS IN PHEROMONE BIOSYNTHESIS OF THE EUROPEAN CORN-BORER, OSTRINIA-NUBILALIS (LEPIDOPTERA, PYRALIDAE)/

Species specificity of moth sex pheromones is in many cases achieved b y means of specific blends rather than by specific components, Two phe romone strains of the European corn borer, Ostrinia nubilalis, use (E) - and (Z)-11-tretradecenyl acetate in different ratios as their pherom one, but show the same ratio of the pheromone precursors (70:30 E/Z-11 -tetradecenoic acid), The hypothesis that the ratio of the pheromone c omponents in the two strains and their hybrids is controlled by the sp ecificity of the reductase system, responsible for conversion of acid to the corresponding alcohol precursors, was tested. Deuterium-labeled alcohols, aldehydes and fatty acids corresponding to the tao pheromon e components were topically applied to the pheromone glands in differe nt ratios and their selective incorporation into pheromone components was determined by gas chromatography with mass: selective detection, A cetylation of the (E)- and (Z)-11-tetradecenols was unselective, where as the corresponding aldehydes and acids were selectively incorporated into the pheromone components, Z strain females selectively metaboliz ed the Z-isomers whereas E strain females converted the E-isomers, The E strain being the most selective of the two strains, Hybrids convert ed both geometric isomers, The relative conversion rate of both E- and Z-isomers of all tetradecenoic acids with the double bond in position s from 7-12, was also determined, In addition to the Delta 11-isomers, the E strain females converted (E)-8-tetradecenoic acid into acetate and the Z strain females converted (E)-12-tetradecenoic acid. None of these substrates occur naturally in the pheromone gland, but (E)-12-te tradecenyl acetate is a pheromone component of the Asian corn borer O. furnacalis, Thus the possibility for conversion of (E)-12-tetradeceno ic acid to acetate in the Z strain, as well as the earlier reported co nversion of (Z)-11-tetradecenoic acid to acetate in O. furnacalis, sug gests that O. furnacalis is closest related to the Z strain of O. nubi lalis.