Nonhost Angiosperm Volatiles and Verbenone Disrupt Response of Western Pine Beetle, Dendroctonus brevicomis (Coleoptera: Scolytidae), to Attractant-Baited Traps

Nonhost angiosperm volatiles and verbenone were tested for their ability to disrupt the response of western pine beetle, Dendroctonus brevicomis LeConte (Coleoptera: Scolytidae), to attractant-baited multiple funnel traps. Verbenone significantly reduced attraction; however, no difference was observed between 4 and 50 mg/24-h release rates. Combinations of six bark volatiles (benzyl alcohol, benzaldehyde, trans-conophthorin, guaiacol, nonanal, and salicylaldehyde), three green leaf volatiles [(E)-2-hexenal, (E)-2-hexen-1-ol, and (Z)-2-hexen-1-ol], and the nine compounds combined did not significantly reduce D. brevicomis response to attractant-baited traps. However, a significant effect was observed when the bark and green leaf volatiles were combined with verbenone. The nine nonhost angiosperm volatiles (NAVs) significantly augmented the effect of both release rates of verbenone, reducing trap catches to levels significantly below that of either release rate of verbenone alone. trans-Conophthorin, a compound reported to have behavioral activity in a number of other scolytids, was not critical to the efficacy of our NAV blend. Our results suggest that the addition of nonhost angiosperm volatiles to verbenone could be important for developing successful semiochemical-based management techniques for D. brevicomis.