Verbenone interrupts the response to aggregation pheromone in the northern spruce engraver, Ips perturbatus (Coleoptera: Scolytidae), in south-central and interior Alaska

Field tests of verbenone, a potential antiaggregation pheromone of the northern spruce engraver, Ips perturbatus (Eichhoff), were conducted in south-central and interior Alaska in stands of Lutz spruce, Picea xlutzii (Little), and white spruce, P. glauca (Moench) Voss, respectively. Addition of 84%-(-)-verbenone at a high release rate to the three-component aggregation pheromone of I. perturbatus (racemic ipsenol, racemic ipsdienol, and 83%-(-)-cis-verbenol), significantly reduced trap catches. The results of this study, combined with previous results on the presence of verbenone in extracts of volatiles collected from feeding I. perturbatus and GC-EAD data, are consistent with antiaggregant behavioral activity of verbenone for I. perturbatus. Key words: Bark beetles; Ips perturbatus; semiochemicals; pheromones; antiaggregation pheromones; verbenone; white spruce; Picea glauca; Lutz spruce; Picea xlutzii; Alaska