BATHYPLECTES PARASITOIDS (HYMENOPTERA, ICHNEUMONIDAE) OF ALFALFA WEEVIL, HYPERA-POSTICA, (COLEOPTERA, CURCULIONIDAE) IN WYOMING

Six Sites were surveyed for Bathyplectes parasitoids (Hymenoptera: Ich neumonidae) of alfalfa weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae), to compare parasitism rates across Wyoming and among Bathyplectes spp. Fourth instars of alfalfa weevil were collected and reared individually until a weevil or parasitoid (adult or pupa) emerg ed. Though relative rates of parasitism for the two most prevalent spe cies (B. curculionis [Thomson] and B. stenostigma [Thomson]) differed among survey sites, the rank order of parasitoids (species prevalence) was consistent across survey sites and three survey years. Of a total of 4,463 weevils assessed, parasitism rates of B. curculionis (mean = 34.5%) > parasitism rates of B. stenostigma (mean = 3.7%) > parasitis m rates of B. anurus [Thomson] (mean = 0.045%). The range of B. curcul ionis parasitism rates (7.4 to 65.3%) was similar to that reported bef ore the last release effort involving B. anurus that occurred in the 1 980's. B. stenostigma was present at all sites, but at low densities: parasitism rates ranged from 0.2 to 16.9%. B. anurus was uncommon, and contributed little to the overall larval parasitism of alfalfa weevil in Wyoming, despite the substantial release effort in the 1980's. Ear lier reports of B. curculionis dominance in the western U.S., and the relative scarcity and ineffectiveness of B. anurus in Wyoming were sup ported by our data.