This Pesticide Might Be Killing off Bees

At least one pesticide from a controversial family of chemicals appears to be a threat to bees and other pollinating insects when applied to certain crops, US regulators announced this week.

The US Environmental Protection Agency (EPA) said residues of the pesticide imidacloprid, which is sold under a variety of brand names, "potentially poses risk to hives when the pesticide comes in contact with certain crops that attract pollinators." A preliminary assessment said residues in concentrations of 25 parts per billion or less on citrus or cotton plants can harm bees and affect their hives, the agency said.

But EPA is still studying what happens when imidacloprid is used on other plants, such as corn and leafy vegetables. Those plants "either do not produce nectar or have residues below the EPA identified level," an EPA statement said.

Imidacloprid is part of a class of pesticides known as neonicotinoids that have come under increasing scrutiny in the United States, Canada, and Europe, because of their possible effects on bees. Bee populations have declined dramatically around the world, and earlier studies indicate that repeated exposure to "neonics" can impair a bee's brain — making it harder for them to find their way back to their hives.

The EPA findings released Wednesday marked the first of four safety assessments of neonic insecticides. Imidacloprid manufacturer Bayer said those chemicals have been extensively studied and are safe when used "appropriately."

"We will review the EPA document, but at first glance it appears to overestimate the potential for harmful exposures in certain crops, such as citrus and cotton, while ignoring the important benefits these products provide and management practices to protect bees," the company said. "We hope the final risk assessment is based on the best available science, as well as a proper understanding of modern pest management practices."

Related: Bees Might Be Addicted to Nicotine-Like Insecticides That Are Killing Them

Environmental groups, meanwhile, criticized the EPA study as too limited. The Center for Biological Diversity (CBD) said the agency failed to study the risks imidacloprid poses to other pollinators like butterflies or birds, and relied too heavily on an industry-funded study.

"The EPA's decision to rely on industry-funded research is absolutely unacceptable, particularly when there has been so much research by independent researchers," Lori Ann Burd, environmental health director at CBD, said in a statement on the findings.

Lisa Archer, head of the food and technology program at Friends of the Earth, said her organization was happy that the EPA study reinforced the link between bee declines and neonicotinoids. But she said the EPA should take imidacloprid and similar chemicals off the market immediately.

"With beekeepers facing continued unsustainable losses, and harm to essential native pollinators mounting, the EPA needs to stop dragging its feet and take decisive action to suspend these bee-toxic pesticides," Archer said.

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