Trail-pheromone sensing in the Asian longhorned beetle (Anoplophora glabripennis): A behavioral study

The Asian longhorned beetle (Anoplophora glabripennis; ALB) is a polyphagous cerambycid that feeds on valuable hardwood tree species such as those in the genera Acer, Populus, and Ulmus. Native to Asia, ALB has become an invasive threat to urban landscapes and forests in Europe and North America. ALB has a complex suite of mate-finding behaviors that are not completely understood, including both chemical and visual cues. Chemical cues include male-produced volatile pheromones, a cuticular hydrocarbon blend serving as a sex-identification pheromone, and a recently identified female-produced trail pheromone used by mate-seeking males. However, the sensory structures used to detect the trail pheromone have not been identified.

Using a two-choice behavioral bioassay, we evaluated the ability of male ALB to follow a pheromone trail after removal of the terminal antennal segments and/or maxillary and labial palps. Results indicate that the palps are primarily responsible for sensing the pheromone; most males without palps did not make a correct choice compared with the majority of intact males that correctly chose the pheromone. Trail-following capabilities of males with removed antennal segments were also impaired in comparison with intact males, indicating that structures responsible for sensing the trail pheromone may also be located on the antennae. The next step in this project is to identify the sensilla responsible for detecting the pheromone using electrophysiological techniques. Our findings will contribute to elucidating the behaviors and mechanisms involved in mate finding, and in determining if the trail pheromone has applications for monitoring and management.