Semiochemical interactions between Scolytus ventralis LeConte and Pityokteines elegans (Swaine) (Coleoptera : Scolytidae)

Two experiments evaluated the effect of baiting uninfested grand fir logs a nd trees undergoing initial attack by Scolytus ventralis LeConte with Pityo kteines elegans (Swaine) pheromone, on the subsequent attack by both specie s. Two more experiments assessed the effect of synthetic bark oil, exo-brev icomin, and P. elegans pheromone on the response by each species to multipl e-funnel traps baited with attractants for the other species. The pheromone of P. elegans on unattacked logs did not have an inhibitory effect on the attack by S. ventralis. However, trees attacked by S. ventralis that were b aited with P. elegans pheromone just after attack, yielded significantly fe wer S. ventralis progeny than the unbaited controls. Neither synthetic bark oil nor exo-brevicomin caused a significant change in the catch of P. eleg ans in traps baited with its pheromone, but the predator Thanasimus undatul us Say was caught in traps baited with (+/-)-ipsenol, (+/-)-ipsdienol and s ynthetic bark oil, and another predator, Enoclerus sphegeus F., was caught in traps baited with exo-brevicomin alone or in combination with ipsenol an d ipsdienol. The results do not support the hypothesis that interference co mpetition based on semiochemical communication occurs between the two speci es.