Pollutants can have severe detrimental effects on insects, even at
sublethal doses. Agrochemicals have been identified as important causes
of pollinator declines, but the impacts of other anthropogenic
compounds, such as metallic trace elements contaminating soils and
waters, have received considerably less attention. Here, we exposed
honey bee colonies to chronic field-realistic concentrations of lead in
food and demonstrate that consumption of this single trace element
impaired bee cognition and morphological development. Honey bees exposed
to the highest lead concentration had reduced olfactory learning
performances and developed smaller heads, which may have constrained
their cognitive functions. Our results show that lead pollutants can
have dramatic effects on honey bee health and may contribute to the
widespread decline of pollinators.