Mercury accumulation in honey bees trends upward with urbanization in the USA

Urbanization has profound implications for associated ecosystems and organisms. Monitoring pollutants inform risk assessments for human and wildlife health. Honey bees (Apis mellifera) forage widely and collect food from many sources. Thus, they may be a robust integrator of environmental pollutants. Here, we collected honey bees from 10 different locations across the United States to quantify their content of total mercury (THg) and methylmercury (MeHg). Although our limited sample size prevented a meaningful statistical evaluation, we found that bees from urbanized areas had higher THg than those from rural areas, with suburban samples intermediate. The MeHg concentrations in all samples were below the detection limit. Despite its limited scope, this first preliminary dataset on Hg levels in honey bees across the United States suggests that urbanization may play a role in increasing Hg exposure to these pollinators, and that honey bees may be a useful biomonitor of the environmental presence of chemical pollutants.