R. Gries et al., SEX-PHEROMONE COMPONENTS OF THE SPRING HEMLOCK LOOPER, LAMBDINA-ATHASARIA (WALKER) (LEPIDOPTERA, GEOMETRIDAE), Journal of chemical ecology, 20(10), 1994, pp. 2501-2511
Two methylated hydrocarbons, 7-methylheptadecane (7) and 7,11-dimethyl
heptadecane (7,11), are female sex pheromone components of the spring
hemlock looper (SHL), Lambdina athasaria (Walker). Compounds extracted
from female pheromone glands were identified by coupled gas chromatog
raphic-electroantennographic detection (GC-EAD) and coupled GC-mass sp
ectrometry (GC-MS) in selected ion monitoring mode. In field trapping
experiments, (7) and (7,11) by themselves were behaviorally inactive,
but in combination attracted numerous male moths. (5,11)-Dimethylhepta
decane (5,11) was detected in female SHL pheromone gland extracts, but
did not enhance attraction to the binary blend of (7) and (7,11). The
sex pheromone of SHL is related to that of congeneric eastern hemlock
looper (EHL), Lambdina fiscellaria fiscellaria (Guen.) [(5,11) and 2,
5-dimethylheptadecane (2,5)] and western hemlock looper (WHL), L.f. lu
gubrosa (Hulst) [(5,11), (2,5) and (7)]. Specificity of the pheromonal
blend, spatial separation of coseasonal EHL and WHL, and temporal sep
aration of sympatric EHL and SHL contribute to reproductive isolation.