FEEDING RESPONSES OF THE WHITE-PINE WEEVIL, PISSODES STROBI (PECK) (COLEOPTERA, CURCULIONIDAE), IN RELATION TO HOST-RESISTANCE IN BRITISH-COLUMBIA

Feeding preferences of the white pine weevil, Pissodes strobi (Peck), for resistant or susceptible Sitka spruce, Picea sitchensis (Bong) Car r., were investigated using three types of laboratory bioassay. In pai red-twig bioassays, fall weevils were significantly deterred from feed ing up to 80% by resistant clones from four British Columbia provenanc es: Green Timbers, Cedarvale, Haney, and Big Qualicum. Females showed greater discrimination than males. Spring weevils were deterred from f eeding by clones from the Green Timbers and Big Qualicum provenances b y up to 60%. Fall males were more consistently deterred than spring ma les, suggesting that some host selection occurs in the fall. Females w ere significantly deterred from ovipositing on twigs from one clone fr om Big Qualicum, and stimulated by clones from Cedarvale when given a choice. Given no choice, however, they were significantly deterred fro m ovipositing, but not feeding by several resistant clones. In agar-di sc bioassays, spring weevils were significantly deterred from feeding by bark from the provenances of Cedarvale and Big Qualicum by up to 86 %. Trees from the provenances of Big Qualicum and Green Timbers caused the most consistent feeding or oviposition deterrency and may rely on this in part as a resistance mechanism. Because not all resistant clo nes and provenances were deterrent, we hypothesize that these trees ma y employ other resistance mechanisms which could be incorporated along with feeding and oviposition deterrency into breeding for resistance.