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New Report: How Neonicotinoids Can Kill Bees

By Aimée Code on 14. December 2016
Aimée Code

The plight of pollinators has grabbed the public’s attention, helped by media stories of parasites, pesticide poisonings, and deserts of urban and agricultural lands where little to no forage can be found. Most experts agree that the startling declines of native bee and butterfly populations, as well as the high annual losses of managed honey bees, can be attributed to multiple factors, including disease, parasites, and a lack of habitat. The role of pesticides in these declines, and specifically of neonicotinoid insecticides, remains unsettled in the minds of many people, in part because pesticide companies have adopted the strategy used so successfully by the tobacco industry and climate change deniers, one of amplifying small uncertainties to sow seeds of doubt about the research or the motives of scientists.

To bring clarity to the debate and to inform discussion, the Xerces Society has published How Neonicotinoids Can Kill Bees. Summarizing hundreds of studies, the new report provides an in-depth look at the science behind the role these insecticides play in harming bees. The text is illustrated with photos and graphics that explain key information, making research that can appear daunting more approachable.


2016 neonic report cover
The new report summarizes the research about the impacts neonicotinoids have on bees, from changing foraging behavior and reduced reproduction to death.


This report replaces the groundbreaking 2012 report, Are Neonicotinoids Killing Bees? The question in that title reflected the uncertainty at that time. Since then, there has been a substantial quantity of published research and the understanding of how neonicotinoids harm bees and other pollinators has grown considerably—removing the question mark. For example, four years ago, knowledge of how neonicotinoids interacted with bumble bees was limited. Studies completed since then create a solid body of evidence showing the damaging effects of these insecticides on bumble bees. This is summarized in How Neonicotinoids Can Kill Bees.

Understanding how neonicotinoids harm bumble bees is especially important as it is estimated that more than a quarter of North America’s bumble bee species are at risk of extinction. In fact, in proposing Endangered Species Act protection for the rusty patched bumble bee, the U.S. Fish and Wildlife Service specifically noted that neonicotinoids and other pesticides could be part of the problem.

How Neonicotinoids Can Kill Bees also highlights risks that neonicotinoids can pose to monarch butterflies. The previously abundant monarch has experienced a more than 80% decline in the eastern United States and an estimated 74% decline in the western states. While there are multiple factors that have driven down monarch numbers, new studies show that larval monarchs can be harmed when milkweeds are contaminated neonicotinoids.

With the U.S. Environmental Protection Agency scheduled to release pollinator risk assessments for three high profile neonicotinoids—clothianidin, thiamethoxam, and imidacloprid—by early 2017, this report provides agency staff with valuable information about the findings by independent researchers. Currently, most decisions about pesticide regulations are made using data provided by companies seeking pesticide registration.

Accompanying the report, Xerces provides recommendations for how to respond to the concerns of neonicotinoids. The recommendations cover issues extending from federal regulation of pesticides to ways backyard gardeners can make a difference. These are published separately.

How Neonicotinoids Can Kill Bees reviews a considerable number of recent studies, but additional research was published after the report was finished—and continues to be released. To ensure that information about the latest studies is accessible, Xerces has created the IPI Database, an online annotated bibliography of new research about pesticide impacts on pollinators and other beneficial insects. This is continuously updated and expanded.



Aimée Code joined the Xerces Society in 2013 to direct its new pesticide program. In that role, she has built a program focused on securing practices and policies that promote ecologically sound pest management. She and her staff evaluate the risks of pesticides, develop technical guidance, and advocate for actions that reduce reliance on and risks of pesticide use in both urban and agricultural settings. Aimée received her master's of science in environmental health with a minor in toxicology from Oregon State University.

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