Bumblebee exposure to microplastics in urban, agricultural and forest environments

Microplastics have been detected in nearly all environments worldwide and are known to be harmful when ingested. In Estonia, most of the research on microplastic pollution is related to the Baltic Sea. Bumblebees may serve as suitable bioindicators for assessing terrestrial microplastic pollution, as they come into contact with multiple surfaces during their lifetime, can fly several kilometres per day, and their electrostatically charged body hairs can attract airborne particles in addition to pollen. In this study, bumblebees were chosen to assess microplastic contamination in urban, agricultural and forest environments in Estonia. Microparticles were washed off from the bumblebees, organic matter was removed from the washing solution, and then the remaining microparticles retained on filters were examined under a microscope. The results revealed that bumblebees collected in urban areas carried higher amounts of microplastics on their body surface compared to those collected in fields and forests. Within urban sites, significantly higher microplastic loads were observed near a busy highway. However, the results might have been affected by weather conditions – bumblebees collected during rainy periods carried fewer particles than those collected during hot and dry conditions. Since no previous studies of this type have been conducted in Estonia, these findings may serve as a baseline for future monitoring of terrestrial microplastic pollution.