Comparative behavioural responses of Dryocoetes confusus Swaine, Dendroctonus rufipennis (Kirby), and Dendroctonus ponderosae Hopkins (Coleoptera: Scolytidae) to angiosperm tree bark volatiles

Abstract

Synthetic, angiosperm bark-derived volatiles, which elicit antennal responses in a number of coniferophagous bark beetles (Coleoptera: Scolytidae), were tested in groups for their ability to disrupt the pheromone-positive response of the spruce beetle (SB), Dendroctanus rufipennis (Kirby), the western balsam bark beetle (WBBB), Dryocoetes confusus Swaine, and the mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins, to attractant-baited traps. One complex mixture disrupted WBBB response to pheromone-baited multiple-funnel traps to a level not significantly different than that in unbaited control traps. No group of compounds, including a group of green leaf volatiles, was active in disrupting SB response, a result that contrasts other published findings and that is different from the behavioral responses that are elicited by nonhost volatiles in other species of coniferophagous bark beetles. For the MPB, the two green leaf alcohols, 1-hexanol and (Z) -3-hexen-1-ol, were highly disruptive. In addition, combinations of compounds from the group consisting of salicylaldehyde, benzaldehyde, nonanal, guaiacol, benzyl alcohol, and conophthorin acted to augment the disruptive activity of the green leaf alcohols.