Honey bee (Apis mellifera) exposure to pesticide residues in nectar and pollen in urban and suburban environments from four regions of the United States

Authors: DEMARES, FABIEN - Non ARS Employee; SCHMEHL, DANIEL - Bayer Cropscience; BLOOMQUIST, JEFFREY - University Of Florida; CABRERA, ANA - Bayer Cropscience; HUANG, ZACHARY - Michigan State University; Lau, Pierre; RANEL, JULIANA - Texas A&M University; SULLIVAN, JOSEPH - Consultant; XIE, XIANBING - Nanchang University, Nanchang, China; ELLIS, JAMES - University Of Florida

Submitted to: Environmental Toxicology and Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2022
Publication Date: 3/9/2022
Citation: Demares, F.J., Schmehl, D., Bloomquist, J.R., Cabrera, A.R., Huang, Z.Y., Lau, P.W., Ranel, J., Sullivan, J., Xie, X., Ellis, J.D. 2022. Honey bee (Apis mellifera) exposure to pesticide residues in nectar and pollen in urban and suburban environments from four regions of the United States. Environmental Toxicology and Chemistry. https://doi.org/10.1002/etc.5298.
DOI: https://doi.org/10.1002/etc.5298

Interpretive Summary: Pesticides are commonly applied by homeowners and local governments for landscape and pest management in urban and suburban environments. Like agricultural landscapes, pollinators in developed environments may be inadvertently exposed to pesticide residues when foraging for resources. Most studies are focused on residue exposure around intensive agriculture. The rise of beekeeping in urban and suburban areas increases the need for assessing risks bees encounter in these environments. Therefore, we sampled honey bee pollen and nectar from beekeeper colonies in urban and suburban environments across four regions of the United States and performed a risk assessment to determine the toxicity of a compound. We found that most pollen and nectar samples were below the level of detection for pesticide residues. However, this varied based on the sampled region. Overall, there was low exposure of pesticides to honey bees from the resources they collect in urban and suburban environments.

Technical Abstract: The risk of honey bee (Apis mellifera L.) exposure to pesticide residues while foraging for nectar and pollen is commonly explored in the context of agroecosystems. However, pesticides are also used in urban and suburban areas for vegetation management, vector control, and the management of ornamental plants in public and private landscapes. The extent to which pesticides pose a health risk to honey bees in these settings remains unclear. We addressed this at a landscape scale by conducting pesticide residue screening analyses on 768 nectar and 862 pollen samples collected monthly over two years from honey bee colonies located in urban and suburban areas in eight medium-to-large cities in California, Florida, Michigan, and Texas (U.S.A.). A risk assessment was performed using the U.S. Environmental Protection Agency’s BeeREX model whenever an oral toxicity value was available for a compound. Chemical analyses detected 17 pesticides in nectar and 60 in pollen samples during the survey. About 73% of all samples contained no detectable pesticide residues. While the number of detections varied among the sampled regions, fewer pesticides were detected in nectar than in pollen. Per BeeREX, four insecticides showed a potential acute risk to honey bees: imidacloprid, chlorpyrifos, and esfenvalerate in nectar, and deltamethrin in nectar and pollen. In general, exposure of honey bees to pesticides via nectar and pollen collection was low in urban and suburban areas across the U.S. and no seasonal or spatial trends were evident. Our data suggest that honey bees are exposed to fewer pesticides in developed areas than in agricultural ones.