Laboratory studies show detrimental effects of metal pollutants on
invertebrate behaviour and cognition, even at low levels. Here, we
report a field study of Western honey bees sampled from an historic
mining site heavily contaminated with metal and metalloid pollution,
particularly arsenic. We analysed more than 1,000 bees from five
apiaries within 11 km of the world's largest gold mine in Southern
France. Bees collected close to the mine exhibited decreased olfactory
learning and memory performances and developed smaller heads.
Three-dimensional scans of bee brains showed that the olfactory centres
of bees sampled close to the mine were also smaller, indicating
impairment of brain. Our study raises serious concerns about the health
of honey bee populations in metal-polluted areas and illustrates how
standard cognitive tests can be used for risk assessment.