This Controversial Pesticide Is Harming Honeybees


The Environmental Protection Agency has finally begun to answer a major question on honeybee health.

This week, the EPA released its first findings on neonicotinoids, a widely-used class of pesticides that many think play a role in the staggering honeybee losses over the last few years. The agency examined imidacloprid — one of four neonic pesticides that the EPA plans to assess, and the most commonly-used neonicotinoid in the United States — and found that it is harmful to bees when applied to certain crops, like cotton or citrus, but not when applied to others, like corn and berries.

That’s because, the assessment found, the main thing that mattered when determining whether or not the pesticide would harm bees was the concentration of the pesticide in the nectar the bees brought back to their hives. If bees returned to their hives with nectar that contained more than 25 parts per billion (ppb) of imidacloprid, it negatively impacted the hive — meaning, as the AP reports, fewer bees and less honey. But if the concentration was less than 25 ppb, the bees fared OK. Some crops contained nectar with higher concentrations than others — while others produce no nectar at all — which explains the difference in danger from crop to crop.

The risk assessment comes as honeybee colonies continue to experience large declines. A survey of 6,100 beekeepers published last May found that 42.1 percent of U.S. managed honeybees were lost between April 2014 and April 2015. Beekeepers in some states saw even higher losses: in Wisconsin and Maine, for instance, an average of 60 percent of bees were lost.


Some of the dangers posed to bees by neonicotinoids are well-known. The pesticides have been found to damage bees’ brains, causing them to forget the scent of food. And general exposure to pesticides as a whole has been found to make bees more susceptible to infection from a certain parasite.

But bee experts say the decline of honeybees and some native bees is likely due to a number of factors — not just pesticides. Another parasite, called the varroa mite, has been implicated in bee deaths — the mite attaches itself to bees and sucks out their circulatory fluid, causing the bees to die. And poor nutrition, caused by more monoculture and fewer natural fields for bees to forage in, could also contribute to bee deaths.

EPA needs to stop dragging its feet and take decisive action to suspend these bee-toxic pesticides

Lisa Archer, director of the Food and Technology Program at Friends of the Earth, said in an emailed statement that her organization was generally satisfied with the EPA’s risk assessment.

“Friends of the Earth is pleased that EPA’s assessment reinforces the strong body of independent science demonstrating that neonicotinoids are a leading driver of bee declines,” she said.


However, she said she wished the EPA took a more comprehensive approach to investigating the pesticides — looking at their cumulative effect on bees, for instance, instead of examining each one individually.

“EPA’s piecemeal approach continues to ignore the risks posed by neonicotinoids to native bees, synergistic and cumulative impacts of exposures to multiple neonicotinoids and other pesticides and fungicides, the impacts of seed coatings, and sublethal effects that also contribute to bee declines,” she said.

The EPA’s finding that imidacloprid does harm bees in some cases doesn’t mean the agency will necessarily act to ban or restrict the pesticide: the agency still has to publish a risk assessment for three other forms of neonicotinoids, as well as an assessment of the overall ecological effects of imidacloprid, all of which it plans to do in December of this year. The agency could take action after the public commenting period for this first risk assessment ends, however, or after the public commenting period for the other three pesticides ends. Already, the EPA has made some moves to restrict neonic use: in April, the agency announced that new permits to use neonicotinoids wouldn’t be approved until the risk assessments for the pesticides are completed. The EPA did not, however, put any limits on existing permits for neoinic use.

Friends of the Earth supports an overall ban on neonics, which they say will help ensure bees aren’t exposed to the pesticides.

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