Neonicotinoid pesticide reduce bumblebees learning and speed
Julie Sørlie Paus-Knudsen, Biosciences
Learning, activity and food gathering are key aspects of a bumblebee life. Neonicotinoids are neurotoxic insecticides suspected to alter these behaviours, ultimately affecting colony development and dynamics.
Using buff-tailed bumblebees, Bombus terrestris, we developed a new experimental method to study the behaviour of several insects simultaneously. We quantified how exposure to imidacloprid affect learning, locomotor activity and food intake. Bumblebees were exposed to three different dosages of imidacloprid through artificial nectar, ranging from field realistic levels to distinctly higher levels in a chronic exposure regime. To assess whether imidacloprid influenced learning, the bumblebees’ ability to discriminate between blue nectar-filled (rewarding) and yellow water-filled (non-rewarding) artificial flowers, we tested the bumblebees in a flying arena. We tracked the bumblebees by use of cameras. This allowed for analysis of flowers choices, locomotor activity and overall number of flowers visited during the foraging bouts of 15 workers simultaneously.
This study shows the successful application of a new method to track bumblebee behaviour. It also shows negative effects on learning, locomotor activity and food consumption, in a dose-dependent manner, when bumblebees are exposed to increasing concentrations of imidacloprid. Moreover, we show that field-realistic doses of imidacloprid have sub-lethal effects on bumblebees.