Abstract
AbstractDouglas-fir cones were collected from 17 seed orchards in California, Oregon, and Washington in the fall of 1983. Cones were completely dissected and seed losses ascribed to the Douglas-fir cone gall midge (Contarinia oregonensis(Foote)), the Douglas-fir seed chalcid (Megastigmus spermotrophus(Wachtl)), the Douglas-fir cone moth (Barbara colfaxiana(Kearfott)), and the fir coneworm (Dioryctria abietivorella(Groté)). There appear to be great differences between orchards, but overallC. oregonensisandM. spermotrophuscollectively destroyed approximately 70% of the filled seed. Physiographic province significantly (P<0.05) explained variation in damage by all insect species between seed orchards. In general, damage by all species increased from northern provinces to southern mountainous provinces. Damage byC. oregonensisandB. colfaxianaappeared to be related to land use or management factors, as well.
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