Green leaf volatiles disrupt responses by the spruce beetle, Dendroctonus rufipennis, and the western pine beetle, Dendroctonus brevicomis (Coleoptera: Scolytidae) to attractant-baited traps

Abstract

We tested the hypothesis that green leaf volatiles (GLVs) disrupt the response of spruce beetles, Dendroctonus rufipennis Kirby, and western pine beetles, Dendroctonus brevicomis LeConte, to attraetant-baited traps. Two green leaf aldehydes, hexanal and (E)-2-hexenal, reduced the number of spruce beetles captured to intermediate levels and one green leaf alcohol, hexanol, significantly reduced spruce beetle trap catches. Together, the green leaf alcohols and aldehydes reduced trap catches by 78.7 and 89.3% for males and females, respectively. The green leaf aldehyde, (E)-2-hexenal, and two green leaf alcohols, (E)-2-hexen-l-ol and (Z)-2-hexen-l-ol, significantly reduced the numbers of male western pine beetles captured and the latter compound also reduced the numbers of female western pine beetles captured. The greatest disruptive effect for the western pine beetle was 46.7% for (Z)-2-hexen-l-ol on males. These results support the hypothesis that GLVs common to non-host angiosperms are disruptive to pheromone and kairomone attraction of conifer-attacking bark beetles. While general GLVs are disruptive to several scolytid species, the most disruptive individual GLV components and blends differ by scolytid species and may reflect differences in the volatile characteristics of their particular ecosystems.