Impact of Leptoglossus occidentalis (Hemiptera : Coreidae) on Douglas-fir seed production

We investigated the effect of feeding by the western conifer-seed bug, Lept oglossus occidentalis Heidemann, on seed production in developing cones of coastal Douglas-Br, Pseudostuga menziesii (Mirb.) France. with respect to s eed bug life stage and sex (nymphs, adult females, and adult males) and tim ing of feeding (early, mid-, and late season cone development). Feeding by females on caged cones for a a-wk period during late season cone developmen t reduced the proportion of full seeds in cones by approximate to 70% compa red with caged control cones. There was no significant difference among nym phs, adult females, and adult males with respect to the proportion of empty or partially fed-upon seeds produced during the same feeding period. Feedi ng by nymphs for 2 wk early in the season resulted in a threefold increase in the number of unextractable seeds fused to cones compared with the contr ol. Weight measurements of harvested seeds indicated that radiography is an accurate tool to distinguish among Douglas-fir seeds that have sustained l ight, moderate, or severe damage. Determining the full impact of L. occiden talis on conifer seed production will require the development of a reliable method to distinguish between naturally alerted seeds and seeds emptied th rough feeding by seed bugs.