Heritability of insect resistance in balsam fir (Abies balsamea)

Balsam gall midge (Paradiplosis tumifex) and balsam twig aphid (Mindarus abietinus) are two major pests in balsam fir (Abies balsamea) Christmas tree plantations in Atlantic Canada. To test the hypothesis that insect resistance is under genetic control, and to evaluate the potential to breed insect resistant trees, I measured the frequency of symptoms associated with feeding by each insect on balsam fir clones in New Brunswick and Nova Scotia tree orchards. Results of a 3 year study suggest moderate to high clone heritability for resistance to each pest. Heritability of resistance, genetic correlations and implications for breeding strategies will be discussed.