Pesticide use is linked to the shrinking of wild bee distributions across the contiguous United States

Authors: GUZMAN, LAURA MELISSA - University Of Southern California; ELLE, ELIZABETH - Simon Fraser University; MORANDIN, LORAN - Pollinator Partnership; COBB, NEIL - Biodiversity Outreach Network; CHESSHIRE, PAIGE - Northern Arizona University; McCabe, Lindsie; HUGHES, ALICE - University Of Hong Kong; ORR, MICHAEL - Stuttgart State Museum Of Natural History; M'GONIGLE, LEITHEN - Simon Fraser University

Submitted to: Nature Sustainability
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2024
Publication Date: 8/27/2024
Citation: Guzman, L., Elle, E., Morandin, L., Cobb, N.S., Chesshire, P.R., Mccabe, L.M., Hughes, A., Orr, M., M'Gonigle, L.K. 2024. Pesticide use is linked to the shrinking of wild bee distributions across the contiguous United States. Nature Sustainability. https://doi.org/10.1038/s41893-024-01413-8.
DOI: https://doi.org/10.1038/s41893-024-01413-8

Interpretive Summary: The decrease in wild bees, especially bumblebees, in North America and Europe has been well-studied. This decline will have significant effects on pollination in natural areas and farms. One possible reason for the drop in native bees is the increase in agricultural activities. Farming intensification can harm wild bees in multiple ways. First, it leads to more pesticide use. Second, it reduces places for bees to nest and flowers for them to find food. This may happen directly or because honey bees could compete for resources. Although there have been experiments and evidence pointing to farming's negative impact on wild bees, it's not clear if these changes are the main cause for the widespread decline across large areas. The study found that certain pesticides, like neonicotinoids and pyrethroids, are major factors contributing to the decline of wild bees in the contiguous United States. These pesticides have led to a decrease in many bee species, with some groups, like Apidae, experiencing up to a 44% decline. This study indicates that certain types of agricultural pesticides are not suitable for conserving pollinators.

Technical Abstract: The decline of wild bees, particularly of prominent groups such as bumblebees, in both North America and Europe has been well-documented. These declines will have major consequences for pollination in natural and agro-ecosystems. One potential driver of declines in native bees is increasing agricultural intensification. Agricultural intensification can have negative impacts on wild bees. First, agricultural intensification has increased the use of pesticides. Second, it can reduce the availability of nesting resources, and floral resources either directly, or via competition with introduced honey bee colonies. While there are a number of field and laboratory experiments, as well as circumstantial evidence, that suggest that agricultural intensification has pernicious effects on wild bees, we have yet to identify whether any of these agricultural-associated changes are responsible for the observed population declines at large (i.e., continental) spatial scales. Testing for such large-scale effects has been hampered by major data gaps for many groups of wild bees and by the fact that many of the hypothesized factors co-vary in complex ways. Here we aggregate museum records, ecological surveys, and community science data from across the contiguous U.S.A. to construct one of the largest data sets of wild bee records to date, which includes 204, 346 observations from 1, 079 bee species with linked ecological and land-use data. Using tools of causal inference and occupancy models, we found that neonicotinoids and pyrethroids are major drivers of wild bee declines across the contiguous United States. Our analysis shows that pesticide use has contributed to declines in wild bee occupancy across many species, with declines of up to 44% in the most affected groups, such as Apidae. These results suggest that the use of some types of agricultural pesticides is not compatible with pollinator conservation.