Assessment of contact exposure to biopesticide tank mixtures in different bee species under controlled laboratory conditions

Bees are essential components of terrestrial ecosystems, providing crucial pollination services for both wild and cultivated plants. However, pollinator populations face increasing challenges due to a combination of anthropogenic pressures, including pesticide exposure and landscape modifications. While biopesticides are often promoted as environmentally friendly alternatives to synthetic chemical pesticides, the potential risks of tank mixtures containing multiple biocontrol agents to non-target insects remain insufficiently investigated. Here, we describe a laboratory-based assay developed to assess contact exposure in three bee species differing in their life profile. The lethal effects and behavioural abnormalities caused by biopesticide tank mixtures were assessed in the highly eusocial honey bee Apis mellifera, the primitively eusocial bumble bee Bombus terrestris, and the solitary mason bee Osmia cornuta. Standardized exposure tests were conducted under controlled laboratory conditions using adult individuals. The assessment included behavioural impairments, mortality, and species-specific sensitivity to the mixtures. The observed results highlight the need to consider the interspecific differences when evaluating the potential risks of external stressors such as pesticides on bees.