Bumblebees that have been exposed to neonicotinoid pesticides are slower to learn how best to collect pollen from wildflowers than are their unexposed counterparts.

Neonicotinoids are widely used insecticides, and their application has been restricted in some countries because of their negative impact on bees. To study the effects of the chemicals on bee foraging, Dara Stanley at Royal Holloway University of London in Egham, UK, and Nigel Raine at the University of Guelph, Canada, observed individual bumblebees (Bombus terrestris) while the insects foraged on two species of wildflower. Bee colonies that had been dosed with the neonicotinoid thiamethoxam released more foragers, and these bees collected pollen more often than did controls. But unexposed bees required fewer visits to flowers to learn how to collect pollen efficiently.

The results suggest that environmental exposure to this insecticide at sub-lethal levels probably changes how well bees forage and pollinate in the wild, say the authors.

Funct. Ecol. http://doi.org/bdn8 (2016)