CHIRALITY OF 5,11-DIMETHYLHEPTADECANE, THE MAJOR SEX-PHEROMONE COMPONENT OF THE HEMLOCK LOOPER, LAMBDINA-FISCELLARIA (LEPIDOPTERA, GEOMETRIDAE)

Of the four possible stereoisomers of 5,11-dimethylheptadecane, the ma jor sex pheromone component of the eastern hemlock looper (EHL), Lambd ina fiscellaria fiscellaria Guen., and the western hemlock looper (WHL ), Lambdina fiscellaria lugubrosa Hulst, (5R, 11S)-5,11-dimethylheptad ecane was the only stereoisomer eliciting electrophysiological respons es by male EHL and WHL antennae. In field bioassays with EHL and WHL p opulations, traps baited with (5R, 11S)-5,11-dimethylheptadecane caugh t as many males as did traps baited with all four stereoisomers combin ed or a synthetic mixture of 5,11-dimethylheptadecanes. Catches in tra ps baited with the other three stereoisomers did not significantly dif fer from those in the unbaited control traps. We conclude that male an tennae lack chemoreceptors for the other three stereoisomers of 5,11-d imethylheptadecane and hypothesize that only (5R, 11S)-5,11-dimethylhe ptadecane is produced by female EHLs and WHLs.