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ARS Home » Southeast Area » Baton Rouge, Louisiana » Honey Bee Lab » Research » Publications at this Location » Publication #406347
Research Project: Using Genetics to Improve the Breeding and Health of Honey Bees

Location: Honey Bee Breeding, Genetics, and Physiology Research

Title: Relative impacts of varroa infestation and pesticide exposure and their effects on honey bee colony health and survival in a high-intensity corn and soybean producing region in northern Iowa

Author
item Rinkevich, Frank
item Danka, Robert
item Rinderer, Thomas
item MARGOTTA, JOSEPH - Louisiana State University
item BARTLETT, LEWIS - University Of Georgia
item HEALY, KRISTEN - Louisiana State University

Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/9/2024
Publication Date: 5/18/2024
Citation: Rinkevich Jr, F.D., Danka, R.G., Rinderer, T.E., Margotta, J., Bartlett, L., Healy, K. 2024. Relative impacts of varroa infestation and pesticide exposure and their effects on honey bee colony health and survival in a high-intensity corn and soybean producing region in northern Iowa. Journal of Insect Science. Vlume 25 Issue 3 Page 18. https://doi.org/10.1093/jisesa/ieae054.
DOI: https://doi.org/10.1093/jisesa/ieae054

Interpretive Summary: Honey bee colonies face a number of pressures that may result in colony losses. Pesticide exposure and Varroa infestation are two of the most frequently cited causes of colony losses. To measure the relative contribution of pesticide exposure and Varroa infestation on colony losses, we set up honey bee colonies across landscapes with a gradient of pesticide exposure levels based on surrounding land use and recorded colony performance in terms of adult bee population, honey production, and colony survival while monitoring Varroa infestation levels. In the first year, colony losses were >70% mostly owing to very high Varroa infestation. In the second year, colonies were treated to control Varroa. Colony losses were significantly reduced to 30% losses due to lower Varroa infestation. Pesticide exposure likely played a secondary role compared to Varroa since pesticide exposure was higher in the second year despite lower colony losses in the second year. Our data shows that colony losses were mostly due to Varroa infestation.

Technical Abstract: The effects of pesticides on honey bee colony health and survival are among the most important concerns in the commercial beekeeping industry. A two-year longitudinal study was performed in corn and soybean growing areas of northern Iowa. Pesticide exposure was measured in stored pollen from three apiaries across a gradient of potential pesticide exposure and compared to measurements of colony health and survival. Pesticide exposure was highest in areas with high intensity corn and soybean production and reduced in areas with forest and pasture. The effects of pesticide exposure on colony performance and survival were influenced by location, season, and year. Pesticide exposure was positively associated with honey bee population size in May 2015 in the Honey and Seed apiaries. Varroa populations across all apiaries in October 2015 were negatively correlated with miticide and chlorpyrifos exposure. Miticide exposure across all apiaries and neonicotinoid exposure in the Honey apiary in May 2015 was higher in colonies that survived at the end of the study. In July 2015, colony survival was positively associated with total pesticide detections in all apiaries and chlorpyrifos exposure in the Honey and West apiaries. Lower Varroa levels were associated with larger honey bee populations, increased honey production, and higher colony survival. This research suggests that honey bees are resilient upon low to moderate pesticide exposure and Varroa are a major cause of reduced colony performance and increased colony losses.