Sexual Dimorphism in Cuticular Hydrocarbons of the White-spotted Longicorn Beetle, Anoplophora malasiaca (Coleoptera : Cerambycidae)

Cuticular hydrocarbons (CHC's) of Anoplophora malasiaca consisted of saturated, monoenyl, dienyl, and trienyl compounds ranging from C22 to C37, but the constituents differed between males and females. Male hydrocarbons were saturated, monoenyl and dienylcompounds from C22 to C30, which accounted for 75.8, 24.0, and 0.2% of total amount, respectively. By contrast, female hydrocarbons contained saturated, monoenyl, dienyl, and trienyl compounds from C22 to C37, which accounted for 80.0, 18.3, 0.6, and 1.1% of the total amount, respectively. Approximately 50% of males showed abdominal bending (AB) behavior towards a glass dummy when female CHC's were applied to it with as yet unidentified active components present in ether eluent from silica gel chromatography of female elytra extract. These male responses were almost at the same level as those to the crude extract of female elytra (53.3%). However, the AB behavior was evoked from 37% of the males when male CHC's were presented along with the female unidentified active components. Few males showed the behavior in response to the ether fraction of male elytra extract even when combined with either female or male CHC's, or to either CHC's or the ether fraction. It was reconfirmed that the unidentified active compounds in the female elytra were a key factor of contact sex pheromone activity. By contrast, CHC's appeared to be non-essential but important for sexual recognition in the mating sequence of A. malasiaca.