Buff-tailed bumblebee, an underrated indicator of air pollution: a comparison of particulate matter accumulation by Bombus terrestris L. and Apis mellifera L.

Abstract

Anthropogenic and natural particulate matter (PM) affects urban and agricultural areas and contaminates the bodies of Apis mellifera (honeybee) and Bombus terrestris (buff-tailed bumblebee). Although both species accumulate PM, scientific interest has primarily focused on A. mellifera as a pollution indicator. This study directly compared the efficacy of honeybees and bumblebees as indicators of PM and its associated trace elements (TEs). Insects were collected from ecological and conventional apple orchards and underwent quantitative analysis of total PM, PM size fractions, and TEs. To establish an environmental context, plant samples and bee products were obtained from both plantations, and screened for PM and/or TEs. Bombus terrestris accumulated 191.3 μg total PM per individual, whereas A. mellifera accumulated 64 μg. Particular PM size fractions were also significantly more abundant on bumblebees. Accumulation patterns of total and large PM on bumblebees differed between the ecological and conventional orchards. Total PM accumulated by both species combined correlated strongly with the total PM covering apple tree foliage in the ecological orchard (r = 0.836) and with grass in the conventional orchard (r = 0.851). The amount of total PM accumulated by B. terrestris strongly correlated with the concentrations of Fe (r = 0.927) and Mn (r = 0.91) in this species. Accumulation of Fe by A. mellifera correlated with the content of this metal in pollen (r = 0.912) and bee bread (r = 0.91), whereas the reverse trend was found for Mo in bee bread (r = –0.912). The results indicate that B. terrestris is a more accurate pollution indicator, with potentially greater efficacy in more polluted areas. The observed differences are most likely attributed to the distinct morphology and behavior of the species.