2006 Annual Report 4d.Progress report. This report serves to document research conducted under a specific cooperative agreement between ARS and the Montana State University. Additional details of research can be found in the report for the parent CRIS 5428-21000-010-00D Pollinating Insect-Biology, Management, Systematics Research. Brood Mortality and Sex Ratio. Alfalfa seed growers manage leafcutting bees to reduce developmental mortality, and are particularly concerned with maximizing female production. To test for sex-specific mortality, we estimated the number of bees of each sex lost to different mortality factors in 4,505 bee cells; results were related to management practices by calculating the number of females produced and lost per gallon of cells (10,000 cells). The number of cells not producing adults ranged from 1759-5425 per gallon in the 6 samples. Among the non-productive cells, the overall estimated mean number of females lost was 1183 compared to an average of 2487 females that emerged as adults. Thus, about 32% of the females were lost before adult emergence, a value similar to that for males (31%). Because of the uneven spatial distribution of the sexes and mortality factors within nests, causes of mortality differed between the sexes. In 7 samples, female mortality exceeded male mortality, due to parasites (4 cases), chalkbrood (2), and pollen ball (1). Male mortality exceeded females mortality in 3 samples, though the cause was unknown. Parasites, chalkbrood, and pollen ball did not always cause female-mortality, but they never caused male-biased mortality. Although parasites kill a greater proportion of females than males, pollen ball actually kills more bees in total. Thus, 36.3% of cells constructed for female offspring contained only pollen balls, 27.7% were lost to parasites, 21.3% to unknown mortality factors, and 19.6% to chalkbrood. But, the best mortality factor to target for control will depend on what proportion of the pollen ball category represents undiagnosed chalkbrood. If the proportion is high, then chalkbrood control could have the greatest overall benefit to female offspring production. Pollen preferences. To examine variation in pollen types collected by females, pollen samples were taken from bees with access to both alfalfa and non-alfalfa blooms within the crop and on adjacent BLM land. Alfalfa pollen was found on all 209 females examined (mean = 54,995 grains per female). Although mustard constituted a much smaller proportion of the available flowers in the field, 73% of females carried it (mean =32,789), and 60% carried at least 1,000 grains. In certain parts of the field, sweetclover also attracted females (17% carried at least 1,000 grains). Over 25% of females also carried kochia pollen. Though this is likely due to contamination by wind-borne pollen in many cases, one female carried over 200,000 grains so was probably foraging on kochia. We also found considerable amounts of spotted knapweed pollen on females (over 22,000 grains on one female). Designing Pest Management Strategies in Seed Alfalfa to Conserve Natural Enemies and Pollinators. Our overall goal is to compare the effectiveness and non-target effects of a traditional insecticide (bifenthrin) that is toxic to non-target insects to the effects of potentially safer and less persistent alternatives (Rimon, Venom, and Ecotrol). Our specific research objectives are to evaluate the impact of reduced-risk insecticides on:. 1)pollinator, pest (lygus, aphids), and natural enemy densities,. 2)floral resources available to flower-visiting insects, and. 3)alfalfa seed damage and seed yield. At each of two sites in Montana in 2005, we established a 5 × 4 array of leafcutting bee nest boxes in an area of one acre. Insecticide applications (three types at each site) were applied twice during the summer in a 0.05 acre area around each of 12 nest shelters. Four shelters within the field and four adjacent to the field were left as unsprayed controls. Each plot was repeatedly sampled with sweep nets to estimate the relative densities of pests, natural enemies, and pollinators. We also marked completed nests within boxes so that we can correlate cell conditions with the insecticide treatments used. This study will continue in 2006 and 2007.