Chemical structure and final steps of biosynthesis of the female sex pheromone of Gastropacha quercifolia (Lepidoptera: Lasiocampidae)

The major volatile constituents in the sex pheromone gland of females of Gastropacha quercifolia (Lepidoptera: Lasiocampidae) were identified as (Z)-5-Dodecenal 1, (Z)-5-dodecenol 2 and (Z)-5-dodecenyl(Z)-5-dodecenoate 3. Synthetic samples of the first two compounds 1 and 2 were able to evoke strong electroantennographic responses from male antennae, however, no electrophysiological activity was found for the ester 3. The final steps involved in the biosynthesis of the three compounds were investigated using deuterated biosynthesis intermediates. (Z)-5-Dodecenoic acid 14 was established as the immediate precursor of (Z)-5-dodecenol 2 which is subsequently converted to the (Z)-5-dodecenal 1. Since a direct desaturation of dodecanoic acid was not observed, the introduction of the double bond appears to take place at an earlier stage of biosynthesis. No evidence was found that the ester 3 might serve as a pheromone pool from which the components 1 and 2 can be derived; on the other hand, (Z)-5-dodecenol and (Z)-5-dodecenoic acid served as the bioprecursors of the ester 3.