Abstract
Volatile foliar terpenes were compared both quantitatively and qualitatively among 20 provenances and 11 cloned genotypes of Sitka spruce (Picea sitchensis Bong [Carr.]) that had been classified as resistant or susceptible to the white pine weevil (Pissodes strobi [Peck]). On average, trees in resistant provenances had significantly lower content of ten terpenes than in susceptible provenances. One resistant clone had significantly higher foliar terpene content, and four resistant clones had significantly lower content than susceptible trees. Thus clonal resistance could be expressed respectively by repellency or lack of apparency. Canonical discriminant analysis revealed that several resistant clones, particularly from the Haney provenance, could be distinguished from others on the basis of their terpene profiles. While there was no clear relationship between terpene profile and resistance, these results suggest that there are probably multiple resistant "chemotypes," and that volatile foliar terpenes may be useful in identifying potentially resistant trees. For. Sci. 43(4):501-508.