Glyphosate herbicide exposure impairs bumblebee colony thermoregulation

Exposure to glyphosate – one of the most widely used herbicides worldwide – can significantly impair bumblebees’ collective ability to maintain hive temperature, researchers report, specifically when food is scarce. The findings reveal a hidden, indirect cost of glyphosate use that’s largely been overlooked – one that can lead to decline in an already challenged yet essential pollinator species. Insects worldwide are declining, a pattern that has been ascribed to myriad increasing anthropogenic stressors, including herbicide and pesticide use. These declines, particularly in crucial pollinator species like bees, represent a significant threat to global ecosystems and economies. Glyphosate is marketed as non-lethal to vertebrates. However, a growing number of studies have reported harmful yet nonlethal physiological and behavioral effects on honeybees. Even so, how the chemical affects the nearly 20,000 species of wild bees remains virtually unknown. To address this knowledge gap, Anja Weidenmüller and colleagues investigated the effects of long-term glyphosate exposure on bumblebees. Weidenmüller et al. found that while environmentally realistic exposure to glyphosate is not directly lethal to bumbles, it did result in a marked decrease in the ability of colony members to maintain hive thermoregulation in instances where resources were also limited. Maintaining hive temperature is critical for colony survival and is the most important factor in brood development. According to the findings, the collective ability to the hive to maintain this temperature decreased by more than 25% during periods of resource limitation. “A potential practical upside to the study of Weidenmüller et al. is that food resources can mitigate the effects of glyphosate, highlighting the potential value of incorporating pollinator plantings and native habitat into working agricultural landscapes,” writes James Crall in a related Perspective.