Comprehensive survey of area-wide agricultural pesticide use in southern United States row crops and potential impact on honey bee colonies

Authors: ZAWISLAK, JON - University Of Arkansas; Adamczyk, John; JOHNSON, DONALD - University Of Arkansas; LORENZ, GUS - University Of Arkansas; BLACK, JOE - University Of Arkansas; HORNSBY, QUINTON - University Of Arkansas; STEWART, SCOTT - University Of Tennessee; JOSHI, NEELENDRA - University Of Arkansas

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/27/2019
Publication Date: 9/2/2019
Citation: Zawislak, J., Adamczyk Jr, J.J., Johnson, D.R., Lorenz, G., Black, J., Hornsby, Q., Stewart, S.D., Joshi, N. 2019. Comprehensive survey of area-wide agricultural pesticide use in southern United States row crops and potential impact on honey bee colonies. Insects. 10(9):280. https://doi.org/10.3390/insects10090280.
DOI: https://doi.org/10.3390/insects10090280

Interpretive Summary: Honey bees forage across a large area, continually scouting the local landscape for diverse food resources. Beekeepers often rely on flowering plants in and around irrigated farmland to maintain their colonies during dry seasons, despite the potential risk of pesticide exposure. Recent declines in pollinator abundance and diversity have focused attention on the role of pesticides and their effects on honey bee health. This investigation examined the landscape within a 2-mile (3.2 km) radius around honey bee colonies in an agricultural setting, and a rural setting without intensive agriculture. More than 10,000 acres of Agricultural land was surveyed to quantify the area of cultivated crops, and area treated with pesticides, including seeds treated with various insecticides as well as those applied to the foliage. Multiple samples of honey, pollen, beeswax and bees were collected from hives in both locations and screened for pesticide residues, to determine if foraging bees were transporting pesticides to hives. Some samples of bee-collected pollen and honey did contain pesticide residues, but were mostly at levels too insignificant to impact bee health. Beeswax samples contained the highest levels of contamination, but most were still relatively low. Samples were screened for 174 common agricultural chemicals and their breakdown products, but only 26 compounds were detected during the two-year study. Of these, 19 were agricultural pesticides, and 7 were miticides applied by beekeepers to control the mite pest, varroa, or the breakdown products of these miticides. These results suggest that bee colonies foraging in agricultural landscapes are potentially exposed to numerous pesticide applications, but these chemicals did not significantly contaminate bees, hives or hive products in this study. And while pesticide exposure can contribute to colony failure, discussions of pollinator health should not narrowly focus on pesticide exposure alone.

Technical Abstract: Honey bees forage across a large area, continually scouting the local landscape for ephemeral food resources. Beekeepers often rely on flowering plants in and around irrigated farmland to maintain their colonies during dry seasons, despite the potential risk of pesticide exposure. Recent declines in pollinator abundance and diversity have focused attention on the role of pesticides and their effects on honey bee health. This investigation examined the landscape within a 2-mile (3.2 km) radius around honey bee colonies in an agricultural setting, and a rural setting without intensive agriculture. More than 10,000 acres of Agricultural land was surveyed to quantify the area of cultivated crops, and area treated with pesticides, including seed treatments and foliar applications of insecticides. Multiple samples of honey, pollen, beeswax and bees were collected from hives in both locations and screened for pesticide residues, to determine if foraging bees were transporting pesticides to hives. Some samples of bee-collected pollen and honey did contain pesticide residues, but were mostly at levels too insignificant to impact bee health. Beeswax samples contained the highest levels of contamination, but most were still relatively low. Samples were screened for 174 common agricultural chemicals and metabolites, but only 26 compounds were detected during the two-year study. Of these, 19 were agricultural pesticides, and 7 were miticides applied by beekeepers, or the breakdown products of these miticides. These results suggest that bee colonies foraging in agricultural landscapes are potentially exposed to numerous pesticide applications, but these chemicals did not significantly contaminate bees, hives or hive products in this study. And while pesticide exposure can contribute to colony failure, discussions of pollinator health should not narrowly focus on pesticide exposure alone.