Host preference by Saperda calcarata Say (Coleoptera: Cerambycidae)

We conducted five laboratory and one field experiments to examine potential host selection mechanisms of Saperda calcarata Say in British Columbia. Olfactory bioassays indicated that female (and possibly male) beetles were attracted to volatiles from leafy twigs of trembling aspen, Populus tremuloides Michaux. However, wounding of the bole, ethanol baiting, or both, did not result in significant orientation toward or attack of trembling aspens in the field. Feeding preferences for trembling aspen were strong for both sexes in choice bioassays, but in no-choice bioassays, females did not discriminate between trembling aspen and black cottonwood, P. trichocarpa Torrey & Gray. Scouler's willow, Salix scouleriana Barrat in Hooker, was fed upon the least by both sexes. When diameter of bolts offered as oviposition hosts was equalized, frequency of oviposition was similar among the three hosts. Our data suggest that feeding preference is the predominant mechanism of host selection by S. calcarata