Location: Honey Bee Research2012 Annual Report
1a. Objectives (from AD-416):
1: Determine the nutrients in pollen that promote worker longevity. 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. 2: Determine the effects of undigested saccharides in high fructose corn syrup (HFCS) on worker physiology and longevity. 2.A. Identify the saccharides in HFCS. 2.B: Determine the effect of saccharides in HFCS on worker physiology and longevity. 3: Evaluate the effects of supplemental feeding on Varroa tolerance, queen production and foraging activity of honey bee colonies. 3.A. Modify the MegaBee diet by adding chemical components that were identified in the pollen mixture analysis. 3.B. Determine the effects of nutrition on Varroa infestation and reproduction in worker and drone cells. 3.C. Determine the role of nutrition on queen production and reproductive potential. 3.D. Evaluate the effects of supplemental protein feeding on the foraging rates of honey bee colonies. 3.E. Improving honey bee immune response to CCD by determining the role of symbiotic microbes in bee nutrition.
1b. Approach (from AD-416):
1. Nutritional value will be evaluated by measuring protein and lipid levels and on bee longevity. The chemical composition of pollens that are more nutritious than MegaBee will be determined. 2. Determine the effects of high fructose corn syrup containing higher saccharides on honey bee longevity. 3. Determine the effects of improved nutrition of the longevity of bees parasitized by Varroa, the reproductive potential of queens, and foraging activity of colonies used for pollination.
3. Progress Report:
We are in the final year of our 5-year plan with only sub-objectives under objective 3 remaining. ARS researchers in Tucson, AZ, made progress on understanding the role of nutrition in maintaining colony health by studying the effects of diet on the growth of parasitic Varroa mite populations, queen rearing, and gene expression in nurse bees. We also identified biomarkers associated with nutritional stress. Microbial communities associated with nutrient acquisition also were identified, and their role in digestion and immunity is being discerned. Under sub-objective 3b, we found that infestation levels and reproductive rates of Varroa were affected by diet. Brood from colonies fed pollen or from open foraging colonies had lower mite levels than colonies fed a supplemental protein diet. A second replicate of this study is underway to determine if results can be repeated. Pollen collected by honey bees often is contaminated with fungicides and pesticides. Under sub-objective 3c, we found that queen rearing was negatively affected when colonies were fed pollen contaminated with a commonly used pesticide alone and in combination with a fungicide. The percentage of queens that were reared to emergence was reduced and those that emerged had incidence of virus compared with queens reared in colonies without pesticide contamination. These results are underscored by findings that nutrition affects the expression of genes in nurse bees that are associated with immunity, protein breakdown and metabolic pathways. Under sub-objective 3d, we found that chronically-malnourished colonies that were completely dependent on supplemental protein diets had lower levels of ß-ocimene, a volatile compound associated with brood and egg laying by queens. The decline was associated with cannibalism of young larvae by adult workers. Subsequent examination of nutrient stores in developing young adult workers revealed that their protein stores were much lower in the pollen-deprived colonies than the pollen-fed colonies. When pollen feeding was resumed, both brood and ß-ocimene production increased. These results underscore the importance of feeding pollen to nutritionally-stressed colonies and further demonstrate the limitations of feeding protein supplements for extended periods. An important difference between pollen and protein supplements is the lack of beneficial microbes that honey bees acquire from collecting nectar and pollen. Studies conducted under sub-objective 3e showed that the most abundant bacteria found in stored pollen and the honey bee’s crop are typically found in the pollination environment or floral nectar. A subset of these bacteria might play a role in preserving pollen, converting it to beebread, inhibiting pathogens, and providing amino acids and other nutrients through metabolic activities. Our study on the protein and amino acid content of pollen before and after it was converted to bee bread showed lower protein levels and higher amino acid concentrations in the bee bread in most instances. These changes might be due to microbial activity during the making of bee bread that cannot be duplicated in protein supplements.
Hoffman, G.D., Eckholm, B., Anderson, K.E. 2012. Honey bee health: The potential role of microbes. In: Sammataro, D. and Yoder, J., editors. Honey Bee Colony Health: Challenges and Sustainable Solutions. Boca Raton, FL. CRC Press. p. 1-12.