Researchers from the University of Texas at Austin investigated the effect of glyphosate on honey bees.

Honey Bee
Credit: RugliG/Getty Images

New research out of the University of Texas at Austin suggests that a popular weed killer might be contributing to the precipitous decline of bees around the world.

The results of the study, published in Proceedings of the National Academy of Sciences this week, found that honey bees "lose some of the beneficial bacteria in their guts and are more susceptible to infection and death from harmful bacteria" when exposed to glyphosate—the most widely used herbicide in the world, and the active ingredient in Roundup.

The researchers exposed honey bees to glyphosate levels similar to the ones know to occur in crop fields, yards and roadsides. They painted colored dots on the bees' backs, so they could be identified and later recaptured. After three days, glyphosate was found to have "significantly reduced healthy gut microbiota" in the exposed bees.

Compared with bees with healthy guts, the bees with impaired gut microbiomes were far more likely to die when they were later exposed to Serratia marcescens, an "opportunistic pathogen" that infects bees around the world.

Researchers found that about half of bees with healthy microbiomes were still alive eight days after exposure to the pathogen, while only a tenth of bees who had been exposed to the glyphosate were still alive.

"We need better guidelines for glyphosate use, especially regarding bee exposure, because right now the guidelines assume bees are not harmed by the herbicide," Erik Motta, a graduate student who co-led the project, said in a statement. "Our study shows that's not true."

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Monsanto, the manufacturer who produces Roundup, reportedly disagrees with the new findings.

"Claims that glyphosate has a negative impact on honey bees are simply not true. No large-scale study has found any link between glyphosate and the decline of the honeybee population," a spokesman told The Guardian. "More than 40 years of robust, independent scientific evidence shows that it poses no unreasonable risk for humans, animal, and the environment generally."

We have a feeling we'll be hearing a lot more about this in the future and we're hoping for the best for our honey producing pals.