Effect of Leptoglossus occidentalis (Heteroptera - Coreidae) on Seed Development of Douglas-fir at Different Times During the Growing Season in Western Oregon

1990

S. 1485-1486

1 Tab., 8 Lit. Ang.

Unselbständiges Werk

200091746

We tested the hypothesis that feeding by the western conifer seed bug, Leptoglossus occidentalis Heidemann, has different effects on Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, seed development at different times during the growing season. Seed bugs were caged on developing cones at densities of 0 and 0.5 per coe for 2-wk periods in mid-June, early July, and late July. Cones were dissected in August and seeds were categorized as undeveloped (aborted), empty seed coat, partially filled seed coat, or healthy. Total number of aborted seeds was significantly related to seed bug feeding, especially during early and mid-season treatments. Partially filled seed was significantly related to both seed bug feeding and season, with the seed of bug effect increasing during seed development. Seed aborted as a result of seed bug feeding during early stages of seed development was 50% higher than in control cages and was indistinguishable from seed abortion attributed to other factors in pprevious studies. These data suggest that effect of seed bugs on seed production have been greatly underestimated in the past.