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Native bees are important ecologically and economically because their role as pollinators fulfills a vital ecosystem service. Pollinators are declining due to various factors, including habitat degradation and destruction. Grasslands, an important habitat for native bees, are particularly vulnerable. One highly imperiled and understudied grassland type in the United States is the Pacific Northwest Bunchgrass Prairie. No studies have examined native bee communities in this prairie type. To fill this gap, the bee fauna of the Zumwalt Prairie, a large, relatively intact remnant of the Pacific Northwest Bunchgrass Prairie, was examined. Native bees were sampled during the summers of 2007 and 2008 in sixteen 40-ha study pastures on a plateau in northeastern Oregon, using a sampling method not previously used in grassland studies—blue vane traps. This grassland habitat contained an abundant and diverse community of native bees that experienced marked seasonal and inter-annual variation, which appears to be related to weather and plant phenology. Temporal variability evident over the entire study area was also reflected at the individual trap level, indicating a consistent response across the spatial scale of the study. These results demonstrate that temporal variability in bee communities can have important implications for long-term monitoring protocols. In addition, the blue vane trap method appears to be well-suited for studies of native bees in large expanses of grasslands or other open habitats, and may be a useful tool for monitoring native bee communities in these systems.

Can. Ent. 105: 733-743 (1973)The question of whether the evolutionary origin of the parasitic bumble bees (Psithyrus Lep.) was monophyletic or polyphyletic has not been convincingly resolved by conventional systematics. In this study numerical taxonomic (NT) analysis was applied to data on wing venation from a set of 13 species of Psirhyrus and 60 species of nonparasitic bumble bees (Bombus Latr.), representing 16 of the subgeneric divisions recognized by Richards. The resultant cluster analysis gave an almost perfect grouping of the constituent Bombus species into their 'correct' subgenera. This was taken as evidence that the NT procedure had yielded discriminant criteria of evolutionary significance. Sin= the same criteria also produced a single grouping of the Psithyrus species, the results support a monophyletic origin for Psithyrus.

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Individual nymphs of the predaceous pentatomid Podisus maculiventris Say were each fed a single first instar Douglas Fir tussock moth larva, Orgyia pseudotsugata McDunnough, and held without further feeding at constant temperature for a known number of days before being frozen. Enzyme-linked immunosorbent assay, ELISA, was used to examine these predators for the presence of prey antigens. The concentration of prey antigens in these predators declined at a linear rate over the 7 days they were held post-feeding. Detectable antigens remained in 50% of the predators after three days at 24°C. On the day in which the prey was consumed (day 0) only 80% of the unstarved predators had detectable prey antigens which suggests the possibility of instinctive killing of prey with little or no subsequent ingestion. The amount of prey antigen in molted and unmolted predators was not statistically distinguishable; although molting interrupts feeding, digestion of the antigen(s) employed in this study seems to be continuous.

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Bumble bees pollinate red clover (Trifolium pratense L.) but impact on seed production depends on the species, abundance, and synchrony with bloom. The objectives of the current study were to examine pollination by a native bumble bee, Bombus vosnesenskii (Radoszkowski), determine the bumble bee fauna associated with red clover in Oregon, and assess if seed set is limiting. In a cage study, yields with B. vosnesenskii (average = 661 kg ha−1) and honey bees (Apis mellifera L.) (average = 640 kgha−1) were comparable. Yields were lower compared with open pollinated plots (average = 1127 kg ha−1), which was likely due to cage effect, as seed set (# seeds/# florets per seed head) was similar in all three treatments (excluding control). Examination of the diversity of endemic bumble bees through field counts and trapping in red clover fields indicated the presence of six species. Over 92% of these were B. vosnesenskii indicating that it is the key pollinator in Oregon. Seed set across four commercial fields was high (0.84–0.88) documenting that existing pollinators, including rented honey bees, and indigenous bumble bees and solitary bees, provide close to maximum pollination of red clover in Oregon. Higher yields will require improved production practices and new cultivars with more heads per plant. Sustainability of high yields in Oregon will depend on protection of indigenous bee pollinators through conservation of habitats that provide nesting sites, judicious pesticide use, and provision of floral resources before red clover bloom.