Variation in damage by terminal shoot insects among jack pine families

The susceptibility of jack pine, Pinus banksiana Lamb., to damage by the white pine weevil, Pissodes strobi (Peck) and the eastern pine shoot borer, Eucosma gloriola Heinrich, was examined over a three-year period (1994–1996) in a 400-family genetic test near New Liskeard, Ontario. Of the 7180 trees examined, white pine weevil damaged 1041 and eastern pine shoot borer damaged 1913 trees, yielding damage frequencies of 14.5% and 26.6%, respectively. Thirty families of jack pine never sustained weevil damage during the study period, while only one family escaped damage by the shoot borer. The expected, and observed, damage rates were significantly different for the weevil, but not for the shoot borer. There was no discernible spatial pattern in the incidence of shoot damage by either insect species, based on the geographic location of the parent trees. The data suggest that there is a basis for pursuing further studies to evaluate genetic resistance in tree improvement programs.