Pheromonal basis of courtship behavior in two gypsy moth parasitoids:Brachymeria intermedia (Nees) andBrachymeria lasus (Walker) (Hymenoptera: Chalcididae).

The pheromonal basis of the courtship behavior of two gypsy moth parasitoids,Brachymeria intermedia andBrachymeria lasus, was traced to a single component in each case. This component was isolated by a combination of absorption and gas-liquid chromatography and shown to elicit some of the courtship behavior typical of these species. Bioassays of extracts from several independent techniques for sequestering pheromones, as well as interspecific assays, support this conclusion. Comparative analyses of both male and female extracts by capillary chromatography show the uniqueness of the pheromonal peak to the female volatile profile.