Glyphosate disrupts the gut microbiota of bees

An American study showed that the most commonly used herbicide in the world seems to modify the gut microbiota* of foraging bees. This alteration could make them more susceptible to opportunistic infections and increase their mortality rate.


Manufacturers of glyphosate insist that their product is inoffensive to humans and animals since it targets a protein that is only present in plants and microorganisms. However, the list of its toxic effects on the fauna and flora keeps growing longer. Researchers from the University of Texas indicate that the intestinal flora of foraging bees is sensitive to glyphosate. This sensitivity could partly explain the decline in the population of these invaluable pollinators.

Glyphosate increases susceptibility of bees to infections

Biologists have studied several hundred worker bees from the same hive. Two groups were exposed to different doses of glyphosate that mimic environmental exposure, while a third group was fed sweetened water. Only three days after the beginning of the experiment, whatever the reason, the main bacterial species decreased in all bees that were in contact with the product. Interestingly, those exposed to the lower doses were the most affected. And we know that intestinal bacteria of bees contribute to their growth and protect them from pathogens which attack and kill mainly foraging bees whose microbiota is altered by the herbicide.

Mass murder

When recapturing bees to study their microbiota, the researchers found only 20% of insects still alive in the group exposed to the highest dosage. They assume that the bees were either disoriented because of the pesticide, or quickly died after exposure, probably infected by pathogenic bacteria. As indicated by other studies, when returning home, bees bring with them herbicide residues, thus exposing the rest of the hive. This study seems to confirm this hypothesis: the entire hive is exposed, including the youngest bees, whose microbiota is still in development.


*Non-pathogenic microorganisms (bacteria, viruses, fungi, parasites) making up our intestinal microbiota and living in our intestines.



Motta, Erick V. S, Raymann, Kasie, Moran, Nancy A. Glyphosate perturbs the gut microbiota of honey bees. Proceedings of the National Academy of Sciences, Oct 2018.