Researchers Test 42 Ag Chemicals for Bee Toxicity

October 28, 2015 01:00 PM
Researchers Test 42 Ag Chemicals for Bee Toxicity

The media has been abuzz for the bees since the insects' declining health has been linked to certain agricultural pesticides. But are agriculturalists really to blame? A recent study evaluating 42 common agricultural pesticides' impact on bee health hopes to provide one more piece of the answer to that question.

“We have to try to get a sense of risk and how to put it in perspective,” says John Adamczyk, USDA Agricultural Research Service research leader. “What excites me about the research is it really helps get a more accurate feeling about what may--or may no--be harmful to bees.”

Bee loss stings more than just their beekeepers. Approximately every third bite of the food that we eat can be attributed, in some way, to a bee, because agriculture depends  heavily on honey bees for pollination.  The bees account for 80% of all insect pollination, according to the Backyard Beekeepers Association. 

What causes bee loss? Reasons include winter kill, pesticide exposure, varroa mites and colony collapse disorder. While pesticide exposure is not the biggest cause of death, it is one of the more controllable causes. “We’re going to help farmers understand what to be careful with,” Adamczyk says.

Adamczyk and his team worked together to create more realistic studies to show how each of the pesticides effect bees. Using a spray tower, the team mimicked real field spraying to show how the chemical could affect bee health, assuming the colony is directly in the path of the spray.

They tested 42 insecticides, fungicides and herbicides, including glyphosate (Roundup) and Sulfoxaflor (Dow), which was the insecticide recently rejected by the Environmental Protection Agency. Each chemical was tested alone in this study to set a baseline for how bees react. In future studies, the researchers will test tank mixes to see if this changes bee reaction. That information will be relayed to farmers.“We’re trying to minimize the risk involved in spraying,” Adamczyk says. 

Here are a few of their findings: 

  • Glyphosate proved to be one of the least toxic chemicals tested. It killed less than 1% of the bees sprayed. Why? The chemical is aimed at killing weeds, not insects, so fewer bees are at risk. “Is it surprising that glyphosate didn’t kill honeybees?" Adamczyk asks. "No."
  • Sulfaoxaflor was also not among the most toxic chemicals for bees. This was surprising, because this new insecticide acts like a neurotoxin, attacking the central nervous system of insects. Yet Sulfoxaflor was recently rejected by the EPA while other chemicals that are more toxic to bees are legal. 

Curious to see how your preferred agricultural mix stacks up? For more information about  the 42 individual chemicals tested, see the full study. Use this information in your operation before you spray.

“We’re all in this together,” Adamczyk says. “Anytime you can minimize a bee kill we’ve done our job.”

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