Effects of Drainage and Severe Defoliation on the Rawfiber Content of Balsam Fir Needles and Growth of the Spruce Budworm (Lepidoptera: Tortricidae)

Analysis of rawfiber content of balsam fir, Abies balsamea (L.) Miller, needles in conjunction with laboratory-reared larvae of spruce budworm, Choristoneura fumiferana (Clemens), during the 1985 growing season indicated significant variations in the quality of food available for consumption by the insect. Two consecutive years of defoliation as well as poor drainage were directly related to higher rawfiber content of the current year's foliage which, in turn, caused a decrease in pupal weight, larval development rate, and survival.