Dose-Dependent and Species-Specific Responses of Pine Bark Beetles (Coleoptera: Scolytidae) to Monoterpenes in Association With Pheromones

Monoterpenes affected the attraction of three sympatric species of bark beetles (Coleoptera: Scolytidae) to pheromone-baited multiple-funnel traps in stands of lodgepole pine. Catches of Ips pini (Say) in traps baited with its pheromone, ipsdienol, were directly related to the release rates of 3-carene, β-phellandrene, and β-pinene. Catches of Dendroctonus ponderosae Hopkins in traps baited with exo-brevicomin and cis- and trans-verbenol were directly related to the release rates of 3-carene, myrcene, and β-phellandrene. Ips latidens (LeConte) exhibited preferences for traps baited with ipsenol and β-phellandrene or β-pinene but not in a dose-dependent fashion. Catches of I. latidens in traps baited with its pheromone, ipsenol, were inversely proportional to the release rates of 3-carene, myrcene, and terpinolene. Similarly, catches of I. pini in traps baited with its pheromone, ipsdienol, were inversely proportional to the release rates of myrcene and terpinolene. These results demonstrate a degree of species specificity among three phloeophagous species with respect to preferred host odours. The bark beetle predators–associates Lasconotus complex LeConte (Coleoptera: Colydiidae) and Corticeus Piller and Mitterpacher sp. (Coleoptera: Tenebrionidae) demonstrated some measure of specificity to monoterpenes in their responses to ipsdienol-baited funnel traps. γ-Terpinene increased attraction of L. complex but had no effect on Corticeus sp., whereas α- and β-pinene increased attraction of Corticeus sp. but had no effect on L. complex.