Interspecific effects of pheromones on the attraction of the bark beetles,Dendroctonus brevicomis andIps paraconfusus in the laboratory.

Dendroctonus brevicomis was attracted to a mixture of theIps paraconfusus pheromones, ipsenol,cis-verbenol, and ipsdienol at 10(-9) g each/μl but was not attracted to these pheromones at higher and lower release rates.I. paraconfusus was not attracted to theD. brevicomis pheromonesexo-brevicomin, frontalin, and myrcene at any release rate tested. Increased release rates of a mixture of the three pheromones ofI. paraconfusus inhibited the attraction ofD. brevicomis to its synthetic pheromones. A mixture of ipsenol + ipsdienol orcis-verbenol alone failed to cause inhibition indicating that at least two of theI. paraconfusus pheromones are required to inhibit the response ofD. brevicomis. The pheromones ofD. brevicomis did not inhibit the attraction ofI. paraconfusus to its pheromones; however, verbenone was a potent inhibitor.