Sound production in Scolytidae: Female sonic stimulus of male pheromone release in two Dendroctonus beetles

The hypothesis that female sonic stimulus may evoke male pheromone release in a behavioural interaction analogous to the known male sonic stimulus of female pheromone release, was confirmed in Dendroctonus pseudotsugae, and also in D. brevicomis. In both species known male-produced substances collected from males stimulated by recorded female stridulation were identified by coupled gas chromatography/mass spectrometry. In a second test with D. pseudotsugae, male pheromone release during recorded female stridulation was evident in the change of male stridulation from the simple attractant chirp to the interrupted chirp, which is known to result from a medium concentration of 3,2-MCH. Also, the D. pseudotsugae male attractant chirp was synthesised with an electronic pulse generator and used to evoke pheromone release. It is concluded that the antiaggregative pheromone of this species is released by each sex at the sonic stimulus of the other sex.