Comparative analysis of honeybees (Apis mellifera) and bumblebees (Bombus terrestris) as environmental indicators of...

Understanding the movement of potentially toxic elements (PTEs) through ecological compartments remains a major challenge in environmental pollution research. We applied in situ sampling of soil, Salvia nemorosa (roots, leaves, and flowers), and two pollinator species-Apis mellifera and Bombus terrestris to trace the exposure pathway of PTEs from soil to pollinators, simultaneously exploring the potential of bumblebees alongside honeybees as bioindicator species. This approach provides a more comprehensive and realistic assessment of element transfer in terrestrial ecosystems. Sampling was conducted in both polluted mining sites (Mining and Metallurgical Complex Bor) and unpolluted natural areas. Concentrations of Cd, Cr, Cu, Fe, Li, Ni, Pb, and Zn were determined using ICP-OAES and metallothionein gene expression in honeybees was assessed as a biomarker of PTE exposure. Results revealed distinct accumulation patterns and exposure pathways between pollinators. Li, Fe, Zn, and Cu were primarily accumulated via plants, whereas Cd, Pb, Ni, and Cr were mainly introduced through atmospheric deposition. S. nemorosa efficiently accumulated PTEs, facilitating their transfer to pollinators via pollen and floral tissues. A. mellifera demonstrated greater efficacy and stability as bioindicators, while B. terrestris was more suited as a sensitive indicator of local pollution. Strong positive correlations in element concentrations between both species support their combined use in biomonitoring. This study highlights the value of a multi-organism, integrative approach to environmental monitoring. By tracking the full pathway of pollutant transfer from soil to pollinators, the study underscores the critical role pollinators play in assessing the ecological impacts of mining-related pollution.