Identification of a female-produced pheromone in a destructive invasive species: Asian longhorn beetle, Anoplophora glabripennis.
Male-produced pheromone components have been reported in the Asian longhorn beetle, Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), but field attraction to these components has been less than overwhelming. Female ALBs were observed rhythmically extending the genitalia in a manner reminiscent of female calling behaviors in other cerambycid species. We thus hypothesized that female ALBs release volatile pheromone while performing this sex-specific behavior. A group of sesquiterpenes, including a major compound α-longipinene and several minor ones α-cubebene, α-ylangene, (-)-α-copaene, α-bergamotene, β-caryophyllene, and α-farnesene, found in genitalia extracts from virgin females elicited male antennal responses. Y-tube olfactometer assays indicated significant attraction of α-longipinene to both sexes in either the presence or absence of host volatiles. This compound was also detected in genitalia extracts from virgin males, though in much lower quantities than in females. Dose-response experiments conducted in the y-tube olfactometer and field both revealed that α-longipinene was attractive at the higher doses, but not at the lower ones. In the field, traps baited with a blend containing α-longipinene, α-cubebene, and β-caryophyllene captured significantly more ALB than solvent controls. The trap catches of α-longipinene combined with either the minor components or host compounds were both greater than those of α-longipinene alone, but the difference was not significant. These results indicate that α-longipinene is a new type of female-produced volatile pheromone in ALB, and the attraction may be synergistically enhanced by several minor components. Sesquiterpenes may play an important role in intraspecies chemical communication of this insect.