Glyphosate Hurts Wild Bees: New Study Finds Popular Herbicide Harms Bee Reproduction

A new study on wild bees and the wildly popular herbicide glyphosate finds the chemical hurts bee colonies by destroying the colonies' ability to maintain temperatures in their hives. The study was conducted by Dr Anja Weidenmüller at the University of Konstanz, Germany.

She writes, "Bumblebee colonies maintain their brood at high temperatures via active thermogenesis, a prerequisite for colony growth and reproduction. 

"Using a within-colony comparative approach to examine the effects of long-term glyphosate exposure on both individual and collective thermoregulation, we found that whereas effects are weak at the level of the individual, the collective ability to maintain the necessary high brood temperatures is decreased by more than 25% during periods of resource limitation. 

"For pollinators in our heavily stressed ecosystems, glyphosate exposure carries hidden costs that have so far been largely overlooked."

A Guardian article on the bees study stated: “Bumblebees are a vitally important group of pollinators [and] the new findings are especially important given the widespread global use of glyphosate,” said Prof James Crall, at the University of Wisconsin–Madison, US, who was not part of the study team. “[Current] environmental safety testing is insufficient for identifying often unpredictable effects on behaviour, physiology, or reproduction that occur at sublethal exposures.” 

The study adds growing weight to the evidence that insect populations vital for bird, butterfly and ecosystem services are under stress and experiencing dramatic declines. A recent study found a more than 75 percent decline over 27 years in total flying insect biomass in Germany.

Glyphosate is widely used on wine grapes in California and elsewhere. State data for California shows the following distribution on wine grapes in 2018 for the potassium salt version. The herbicide is widely used in wine country on both supermarkets wines and fine wines.

The map below shows where one form of the herbicide is used on wine grapes in California, using 2018 (the most recent available) state data from the Dept. of Pesticide Regulation.