Popular weedkiller link to bee deaths

Scientists find evidence that glyphosate, the active ingredient in many brands, could be killing honey bees

BEES could be dying as a result of exposure to some of Britain’s most popular weedkillers, research suggests.

Scientists in the US found evidence that glyphosate, the active ingredient in Roundup and many other brands, may be contributing to the decline of honey bees. Glyphosate herbicides are the most widely used in UK agriculture, with 5.4million acres of farmland across Britain treated with the chemical annually.

The study, by the University of Texas, showed worker bees exposed to the glyphosate lose beneficial gut bacteria, which is likely to leave them vulnerable to infections.

Erick Motta, the lead researcher, said: “We need better guidelines for glyphosate use, especially regarding bee exposure, because right now the guidelines assume bees are not harmed by the herbicide. Our study shows that’s not true.”

In a test case in the US last month a jury found that Roundup would have contributed to former groundskeeper Dewayne Johnson’s cancer and maker Monsanto was ordered to pay £226million in damages. The company has vowed to appeal and maintains that its glyphosate products are safe, as do the other manufacturers of the chemical.

In the new study scientists exposed honey bees to glyphosate at levels known to occur in crop fields, gardens and roadsides.

After three days, the exposed bees were found to have significantly reduced levels of healthy gut bacteria compared to non-exposed insects.

The most affected benign bug, Snodgrassella alvi, is critical to bee well-being, helping the insects process food and keep out dangerous infectious agents. Bees with impaired gut “microbiomes” were also far more likely to die when later exposed to a harmful invasive bacterium. Nine out 10 bees died compared to five out of 10 of the insects that were not exposed to glyphosate.

The scientists urged farmers and homeowners to avoid spraying glyphosate herbicides on flowering plants likely to attract bees.

Prof Dave Goulson, from the University of Sussex, said: “Those of us that study bees have long ago come to the conclusion that colony health is adversely affected by a number of interacting stressors, including exposure to cocktails of insecticides and fungicides, impacts of pathogens, and effects of poor nutrition. It now seems that we have to add glyphosate to the list of problems that they face.”

But a spokesman for Bayer, Monsanto’s parent company, said: “Claims that glyphosate has a negative impact on honey bees are simply not true.

“More than 40 years of robust, independent scientific evidence shows that it poses no unreasonable risk for humans, animals, and the environment generally. Regulatory authorities carefully consider these issues when they approve new pesticides for use.”

The research was published in the journal Proceedings of the National Academy of Sciences.