Spruce terpenes: expression and weevil resistance

White spruce (Picea glauca (Moench) Voss) and Engelmann spruce (Picea engel mannii Parry) parent trees were selected that were rated as highly resistan t or highly susceptible to white pine weevil (Pissodes strobi Peck) attack, based upon attack measurements on their open-pollinated progeny. For each parent, levels of terpenes or other volatiles in leaf and bark were highly correlated within ramets and highly variable within progeny. For the ramets , levels of individual terpenes could not be used to predict resistance cla ss because of their large variability. A multivariate model developed using the terpenes showing the greatest differences between resistant classes wa s found to predict the resistance levels of the original ortets well, with 15 of 16 parent trees correctly predicted using either leaf or bark chemica ls. These models failed to predict the resistance level of the open-pollina ted progeny. Discriminant analysis was also attempted by dividing the ramet data into independent sets and using each set to predict the other. Again, prediction was no better than chance. We conclude that there is no merit i n using terpenes as a selection tool to find resistant genotypes amongst wh ite and Engelmann spruce populations.