A common weed killer is to blame for the indirect death of honey bees, shows a study recently published in the journal PNAS. US Researchers from the University of Texas at Austin led by Erick Motta explain that honey bees exposed to glyphosate lead to the loss of beneficial gut bacteria in the bees and make them less resistant to infection and harmful bacteria.
The authors concluded that the study is strong evidence of why honey bees and native bees have seen such a decline around the world.
“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,” warns Erick Motta.
Glyphosate is known to only interact with enzymes in plants or microorganisms, not with animals, humans or bees.
However, the study saw that the bee’s gut microbiome is affected by glyphosate, rendering the insects unable to fight infections.
Professor Nancy Moran (the University of Texas at Austin) and the team of researchers have tested to see what happens to honeybees which are exposed to glyphosate used in crop fields, yards or on the road. To track and capture their test subjects, the researchers placed a colored dot of paint on the bees’ backs.
Tests showed that after three days, the herbicide reduced the healthy but bacteria. Initially, there were eight species of healthy bacteria, which after three days four of them were significantly decreased.
The bacterial species hit the hardest was one microbe (Snodgrassella alvi) that helped bees process food and defended themselves against infections. A weaker gut microbiome meant an increased risk of being exposed to an opportunistic pathogen – Serratia marcescens, which infects all the weaker bees in the world.
After eight days of being exposed to the Serratia marcescens, half of the bees that had a healthy microbiome were alive. The ones with the altered microbiome (from the exposure to the herbicide) had a lower chance of survival: 10%.
Moran concluded that:
“Studies in humans, bees and other animals have shown that the gut microbiome is a stable community that resists infection by opportunistic invaders. So if you disrupt the normal, stable community, you are more susceptible to this invasion of pathogens.”
The authors recommended that farmers, homeowners, and landscapers shouldn’t use herbicides that contain herbicides on the plants that attract bees.
Doris’s passion for writing started to take shape in college where she was editor-in-chief of the college newspaper. Even though she ended up working in IT for more than 7 years, she’s now back to what he always enjoyed doing. With a true passion for technology, Doris mostly covers tech-related topics.