Foraging bumblebees acquire a preference for neonicotinoid-treated food with prolonged exposure

Social bees represent an important group of pollinating insects but can be exposed to potentially harmful pesticides when foraging on treated or contaminated flowering plants. To investigate if such exposure is detrimental to bees, many studies have exclusively fed individuals with pesticide spiked food, informing us about the hazard but not necessarily the risk of exposure. Whilst such studies are important to establish the physiological and behavioural effects on individuals they do not consider the possibility that exposure may change over time. For example, many pesticide assays exclude potential behavioural adaptations, such as a rejection of harmful compounds by choosing to feed on an uncontaminated food source, which would behaviourally lower the risk of exposure. Here we conducted an experiment over 10 days in which bumblebees forage on an array of sucrose feeders containing a range of concentrations (0, 2 & 11 parts per billion) of the neonicotinoid pesticide thiamethoxam....