The effects of anthropogenic toxins on honey bee learning: Research trends and significance

Managed honey bees are experiencing high rates of colony loss, in part due to widespread exposure to agrochemicals and other environmental toxins. The ability to learn about relevant environmental stimuli is an important skill necessary for foraging and navigation, although it is sometimes impaired in bees that have been exposed to toxins or other stressors. Here, we review the effects of anthropogenic toxins (which we divide into five major classes: insecticides, acaricides, biopesticides, other agrochemicals, and other toxins) on learning performance in European honey bees. We discuss the general trends of these studies, including that neurotoxic insecticides are overwhelmingly the most well-studied, and that most studies focus on acute exposure of individual, adult bees to a single toxin. Protocols for field-relevant exposure vary widely among labs, and we make suggestions to aid in the standardization of future studies. We review the relevance of learning studies for toxicological risk assessment, concluding that they are valuable tools for assessing sublethal behavioral effects of toxins. Their inclusion in risk assessment studies would be an improvement over current procedures, which focus largely on lethality.