Electrophysiological and behavioral responses Dendroctonus frontalis and D. terebrans (Coleoptera: Curculionidae) to resin odors of host pines (Pinus spp.)

Southern pine beetle (Dendroctonus frontalis Zimmermann) and black turpentine beetle (Dendroctonus terebrans Olivier) are two sympatric bark beetle pests of the southeastern United States of America that adversely affect pine (Pinus spp.) health. Successful host tree colonization and reproduction is dependent on a chemical communication system that includes compounds produced by both the beetles and their host trees. To better understand the role of host volatiles in the ecology of these species, we (1) used coupled gas chromatography-electroantennographic detection (GC-EAD) to analyze olfactory sensitivity of D. frontalis and D. terebrans to volatile constituents of host resin, and (2) investigated olfactory stimulants for behavioral effects on both pest species and a major predator, Thanasimus dubius Fabricius (Coleoptera: Cleridae) in field trapping studies. In GC-EAD analyses of the headspace of fresh host resin, antenna of both D. frontalis and D. terebrans produced strongest responses to alpha-pinene, beta-pinene, myrcene, and 4-allylanisole. Field tests indicated that alpha-pinene, beta-pinene, and 4-allylanisole significantly enhanced attraction of D. frontalis, D. terebrans, and T. dubius to traps baited with attractive pheromone components of both bark beetle species, and myrcene diminished this response for D. frontalis. The observed attractive synergism of 4-allylanisole contrasts with previously reported repellency of this compound for D. frontalis and instead suggests this semiochemical may have multiple ecological roles for this species. Lures used for monitoring D. frontalis may be enhanced in sensitivity by adjusting the composition of their host odor components.