Host preference ofPissodes strobi peck (Coleoptera: Curculionidae) reared from three native hosts

Abstract

In forced feeding bioassays,Pissodes strobi reared from eastern white pine, Engelmann spruce, or Sitka spruce failed to discriminate between these three host species. However, results of choice feeding bioassays suggest that eastern white pine is the ancestral host of the two westernP. strobi populations. Comparative feeding data obtained under conditions of choice support the hypothesis thatP. strobi has dispersed westward across the North American continent, adapting its host selection behavior in turn to Engelmann spruce and then Sitka spruce. WhereasP. strobi reared from eastern white pine preferred to feed on its natural host rather than on the two western spruces,P. strobi reared from Engelmann spruce did not discriminate between eastern white pine and its natural host, Engelmann spruce, but fed significantly more on these two hosts than on Sitka spruce.P. strobi reared from Sitka spruce, on the other hand, fed equally on all three native host species. Our data support the contention of Smith and Sugden (1969) that the two western weevils are eco types ofP. strobi. Comprehensive research on behavioral adaptations to new host species may allow the threeP. strobi populations to be distinguished as legitimate ethospecies.