Cuticular Hydrocarbons as Chemotaxonomic Characters for Bark Beetles: Dendroctonus ponderosae, D. jeffreyi, D. brevicomis, and D. frontalis (Coleoptera: Scolytidae)

Abstract

Cuticular hydrocarbons were extracted from adults of the sibling species Dendroctonus ponderosae Hopkins and D. jeffreyi Hopkins and from the closely related species D. brevicomis LeConte and D. frontalis Zimmermann. Four distinct chemical mixtures of cuticular hydrocarbons were identified by gas chromatography-mass spectrometry. Five classes of hydrocarbons were present: n -alkanes, alkenes, terminally branched methylalkanes, internally branched monomethylalkanes, and dimethylalkanes. Each of the two species pairs, D. ponderosae-D. jeffreyi and D. brevicomis-D. frontalis, had similar hydrocarbon profiles, yet unique hydrocarbon components were found. The best hydrocarbons for separating D. ponderosae and D. jeffreyi are the 3,7-dimethylalkanes. Obvious diagnostic hydrocarbon components are the 3,X-dimethylnonacosanes in D. frontalis and the homologous series of n -alkanes from n -hentriacontane to n -pentatriacontane in D. brevicomis . Host tree and geographic location did not qualitatively affect the cuticular hydrocarbon composition of D. frontalis. Hydrocarbon patterns of male and female D. frontalis were qualitatively and quantitatively similar. The species-specific nature of cuticular hydrocarbon mixtures in these four species and their potential for nondestructive species discrimination are discussed.