The capacity of conophthorin to enhance the attraction of two Xylosandrus species (Coleoptera: Curculionidae: Scolytinae) to ethanol and the efficacy of verbenone as a deterrent

Exotic invasive ambrosia beetles are among the most economically important pests of nursery stock and forest systems in the U.S.A. Conophthorin, a common bark volatile of deciduous trees, acts as an attractant for the exotic black stem borer, Xylosandrus germanus (Coleoptera: Curculionidae: Scolytinae). Nevertheless, the extent to which a congener, Xylosandrus crassiusculus and other ambrosia beetles are attracted to conophthorin remains unclear. It is also unknown whether conophthorin enhances the attraction of these Xylosandrus beetles to traps baited with ethanol. In the present study, we evaluated the extent to which conophthorin enhances the attraction of X. crassiusculus and X. germanus to ethanol-baited traps. We also tested the capacity of verbenone, an anti-aggregation pheromone component of several coniferophagous bark beetles, to deter both species. More X. crassiusculus were captured in traps baited with both conophthorin and ethanol than in those containing either compound alone, suggesting that conophthorin enhances the response of X. crassiusculus to ethanol. This combination was also attractive to the checkered beetles Madoniella dislocatus and Pyticeroides laticornis (Coleoptera: Cleridae). Verbenone deterred both X. germanus and X. crassiusculus, suggesting that the use of conophthorin and ethanol as an attractant and verbenone as a deterrent can be incorporated into an effective integrated pest management programme.