Bumblebees exposed to pesticides bring pollen back to their colonies less often and have lower body mass than unexposed counterparts.

Hannah Feltham at the University of Stirling, UK, and her colleagues fed bumblebees (Bombus terrestris; pictured) in the lab for two weeks on pollen and sugar water laced with doses of the pesticide imidacloprid that they might come across in the field. The researchers then attached tiny radio tags to the bees and placed colonies out in the field to monitor their foraging behaviour. They found that exposed insects carried pollen back to the colonies on 40% of trips, compared with more than 60% for unexposed bees.

Credit: Redmond Durrell/Alamy

Gemma Baron and her colleagues at Royal Holloway University of London in Egham, UK, tested the effect of the pesticide λ-cyhalothrin. They discovered that pesticide-treated colonies produced smaller workers than unexposed colonies.

The researchers suggest that pesticides could contribute to a reduction in queen production and to bumblebee colony failure.

Ecotoxicology http://doi.org/rct (2014); J. Appl. Ecol. http://doi.org/rcv (2014)