houston the worlds most widely used weed killer may also be indirectly causing death of honey bees according to a studyresearchers from the university of texas at austin in the us found that honey bees exposed to glyphosate lose some of the beneficial bacteria in their guts and are more susceptible to infection and death from harmful bacteriascientists believe this is evidence that glyphosate might be contributing to the decline of honey bees and native bees around the worldwe 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 thats not true said erick motta who led the study published in the journal pnassince glyphosate interferes with an important enzyme found in plants and microorganisms but not in animals it has long been assumed to be nontoxic to animals including humans and beesthe study shows that by altering a bees gut microbiome the ecosystem of bacteria living in the bees digestive tract including those that protect it from harmful bacteria glyphosate compromises its ability to fight infectionthe researchers including professor nancy moran from the university of texas at austin exposed honey bees to glyphosate at levels known to occur in crop fields yards and roadsidesthey painted the bees backs with coloured dots so they could be tracked and later recapturedthree days later they observed that the herbicide significantly reduced healthy gut microbiota of eight dominant species of healthy bacteria in the exposed bees four were found to be less abundantthe hardest hit bacterial species snodgrassella alvi is a critical microbe that helps bees process food and defend against pathogens researchers saidthe bees with impaired gut microbiomes also were far more likely to die when later exposed to an opportunistic pathogen serratia marcescens compared with bees with healthy gutsserratia is a widespread opportunistic pathogen that infects bees around the worldabout half of bees with a healthy microbiome were still alive eight days after exposure to the pathogen while only about a tenth of bees whose microbiomes had been altered by exposure to the herbicide were still alivestudies in humans bees and other animals have shown that the gut microbiome is a stable community that resists infection by opportunistic invaders moran saidso if you disrupt the normal stable community you are more susceptible to this invasion of pathogens he saidresearchers recommend that farmers landscapers and homeowners avoid spraying glyphosatebased herbicides on flowering plants that bees are likely to visit