HESPEROPHYLAX OCCIDENTALIS (TRICHOPTERA, LIMNEPHILIDAE) - ELECTROANTENNOGRAM STRUCTURE-ACTIVITY STUDY OF SEX-PHEROMONE COMPONENT 6-METHYLNONAN-3-ONE

Electroantennogram (EAG) analyses of Hesperophylax occidentalis male a nd female antennae were used to generate dose-response curves for synt hetic, racemic 6-methylnonan-3-one and to demonstrate the chemical spe cificity of male antennal olfactory cells. Male antennae responded to 6-methylnonan-3-one, the main female pheromone component. Females also demonstrated a response to 6-methylnonan-3-one, but a smaller one tha n males. The chemical specificity of male antennal receptors was deter mined by comparing EAG activity of synthetic, racemic 6-methylnonan-3- one and a series of structural analogs. The three structural parameter s considered, including keto position, chain length, and methyl-group position, were demonstrated to contribute significantly to the recepti on of synthetic, racemic 6-methylnonan-3-one by male antennae. For str aight-chain nonanones with keto groups at different positions, nonan-3 -one elicited the greatest EAG responses from male antennae. For strai ght-chain alkan-3-ones with different chain lengths, the EAG responses of male antennae to nonan-3-one and decan-3-one were the same, but gr eater than those to other chain lengths. For methyl-branched nonan-3-o nes, 6-methylnonan-3-one elicited greater EAG responses from antennae than analogs with the methyl group at another position.