Toxicity of Pine Resin Vapors to Three Species of Dendroctonus Bark Beetles

Abstract

The vapor toxicity or saturated resin vapors of both host and non-host pines was determined for three species of Dendroctonus: D. brevicomis Le Conte, D. monticolae Hopkins, and D. jeffreyi Hopkins. Results with hard pines substantiate the hypothesis that bark beetles of this genus can tolerate saturated vapors of host resin but not of non-host resin, suggesting that resin is a determining factor in host specificity. Results with sort pines do not substantiate the hypothesis, suggesting that other properties of resin or non-resinous characteristics of these pines determine host specificity. A delayed effect in many tests with hard pine host resin suggests that even host resins can be deleterious under certain conditions. Variable results were obtained with hybrid pines. Resin vapors of non-host✕non-host hybrids were toxic. D. brevicornis and D. jeffreyi were usually significantly affected by non-hosthost✕host hybrid resin vapors while D. monticolae was not. The overall results suggest that resin in some capacity may be an important factor in host resistance.