Credit: Daniel Prudek

Monsanto’s Roundup Weed Killer Harmful to Honey Bees

by | September 28, 2018

A study has shown that the active ingredient in Monsanto’s Roundup is harmful to honey bees guts.

Roundup contains glyphosate, which decreases microorganisms in honey bee guts, leaving them extremely vulnerable. Honey bees exposed to levels of glyphosate commonly found in the environment had decreased amounts of microbiota in their gut—which leaves them prone to early death, according to a study released today.

These “microbiota” regulate the bees’ metabolism, weight gain, and the immune system. These new findings go against previous claims that glyphosate does not harm wildlife, and maybe a possible clue as to why honey bee colonies are dying at an increased rate.

harmful to honey bees
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“Gut microbiota is involved in nutrition for bees, helping break down components of cell walls in pollen grains and protecting against different pathogens,” Nancy Moran, senior author of the study and evolutionary biologist at the University of Texas, said in an interview with EHN.

For the study, which was published this week in the Proceedings of the National Academy of Sciences, researchers collected hundreds of honey bees from one hive and exposed some of them to levels of glyphosate found in the environment, and then returned them to the hive. After only three days, the total gut bacteria already decreased in the treated bees. When treated bees were exposed to a harmful pathogen, they were more likely to die than their untreated counterparts.

harmful to honey bees
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Harmful To Honey Bees

The experiment was repeated with other hives and bees and saw the same devastating results of how the weed killer was harmful to honey bees.

It had been thought that glyphosate was harmless to bees because it targets an enzyme only found in plants and microorganisms, however, the bacteria in a bees gut does contain that same enzyme. “It’s true the bee itself has no molecular targets from glyphosate but its gut bacteria do have targets,” she said. “It’s similar to humans taking antibiotics where there can be trouble if you upset the normal microbiota.”

The value of insect pollination to U.S. farming is about $16 billion a year, and honey bee colonies — and pollinators in general — are in trouble. Making this study very concerning.

A third of our food relies on pollinators, and while honey bees are one of many species that pollinate, the U.S. Department of Agriculture estimates about a 30 percent overwinter colony loss annually for honey bees over the past decade.

Other research, from China and published in July, showed that honeybee larvae grew more slowly and died more often when exposed to glyphosate. An earlier study, in 2015, showed the exposure of adult bees to the herbicide at levels found in fields “impairs the cognitive capacities needed for a successful return to the hive”.

When asked to comment on the study, a spokesman for Monsanto said: “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. More than 40 years of robust, independent scientific evidence shows that it poses no unreasonable risk for humans, animal, and the environment generally.”

People are known to widely consume glyphosate residues in food – like children’s breakfast cereal – but the impact on health is controversial. In August a US court ordered Monsanto to pay $289m in damages after a jury ruled that the weedkiller caused a terminally ill man’s cancer. The company filed papers to dismiss the case on 19 September.

The weedkiller, sold as Roundup, won a shortened five-year lease in the EU in 2017. In 2015, the World Health Organisation’s cancer agency, the IARC, declared glyphosate “probably carcinogenic to humans,” although a few international agencies subsequently came to opposite conclusions. Monsanto insists glyphosate is safe.

Weight in with your opinion in the comments, do you think the weed killer is harmful to honey bees?

Julie Nealon

Associate Editor, New York USA | Contactable via [email protected]


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