Antennal olfactory responsiveness of three sympatricIps species [Ips avulsus (Eichhoff),Ips calligraphus (Germar),Ips grandicollis (Eichhoff)], to intra- and interspecific behavioral chemicals.

Electroantennograms (EAGs) from male and femaleIps avulsus, I. calligraphus, andI. grandicollis to their pheromones and selected host odorants or kairomones verified the presence of antennal olfactory receptors in both sexes of each species capable of detecting ipsdienol, ipsenol,cis- andtrans-verbenol,endo-brevicomin α-pinene, frontalin, and verbenone. Each species possesses receptors with lower thresholds and in greater abundance for the compounds they produce and to which they are behaviorally most responsive. Detection of bothIps andDendroctonus pheromones by the three cohabiting species provides a sensory basis for olfactory interactions among the species. Differences in both threshold and saturation levels for EAGs for the various behavioral chemicals could denote differences in specific behavioral roles for each compound.