2012 Annual Report
1a.Objectives (from AD-416):
1. Evaluate the performance of selected colonies during pollination of different crops in a migratory beekeeping operation. 2. Examine colony nutrient processing of forage collected from crops of varying nutritive value. 3. Compare levels of known beneficial and pathogenic colony microbes during pollination of different crops. 4. Determine exposure of commercial colonies to chemical treatments encountered during pollination. 5. Characterize the microbial communities associated with colonies during pollination of different crops in a migratory beekeeping operation.
1b.Approach (from AD-416):
Examine nutrient processing , pesticide exposure, microbial communities, and colony performance in selected colonies over an entire migratory pollination season.
This is the final report for this project which terminated May 31, 2012. ARS scientists in Tucson, AZ, found that migratory bee colonies experienced repeated cycles in population and health related to the accumulation and depletion of pollen stores. Twenty-four individual migratory beekeeping colonies were followed through five crop environments and a holding yard from February to October 2010. During 14 biweekly timepoints, colony performance and key colony components were evaluated to assess changes in colony nutrition, brood rearing, chemical exposure, microbes, and colony health. Fifty percent of colonies experienced supersedure or loss of a queen through the season. Comb area estimates indicate that stored pollen accumulated rapidly during bloom periods and decreased rapidly as bee populations increased. Most notably, bees did not adjust their populations to match the available forage outside the colony. Instead, worker and drone brood production followed accumulation of stored pollen within the colony with a 1-2 week lag period. The nutritional state of nurse bees, as shown by total body mass, hypopharyngeal gland protein content, and fat body lipid contents, was also strongly correlated with stored pollen availability with a slight 1-2 week lag time. This lag period between peak stored pollen accumulation, peak brood production and nurse bee health occurred as bee populations increased and overshot available colony food stores. Beneficial microbes also followed the cycle of stored pollen and colony health with a slight lag period. Microbial titers of the beneficial lactic acid bacteria Lactobacillus konkeii in nurse bees were strongly correlated with positive colony metrics of growth, performance, and worker health. Honey bees were also exposed to a variety of agricultural chemical treatments in their incoming food materials. Three herbicides, nine fungicides, six insecticides, and two miticides were detected in corbicular pollen collected from foragers in four crop environments. Significant chemical exposure may come from forage located outside the immediate apiary. Notably, the highest chemical exposures came from corbicular pollen collected from colonies in an organic almond orchard. These results indicate that migratory colonies do not adjust their populations to match available floral forage outside the colony, but endure population cycles of increase and decline due to overexploitation of colony pollen stores.
This project addresses the following objectives in the parent project by providing background field data:
1.A. Determine the effects of pollen mixtures on worker protein and lipid stores and longevity.
1.B. Characterize the chemical composition of pollen mixtures that optimize worker protein and lipid stores and longevity.
3.C. Determine the role of nutrition on queen production and reproductive potential.