Bee gut microbiota as an emerging endpoint for the environmental risk assessment of pesticides

Pollinator health is increasingly threatened by multiple stressors, including climate change, nutritional imbalances, pathogens, and pesticides. Environmental Risk Assessment (ERA) aims to evaluate the potential environmental harm of pesticides and regulate their use in agriculture. However, current ERA frameworks present significant shortcomings, particularly in addressing sublethal and microbiota-mediated effects. Incorporating bee gut microbiota as a biomarker-based monitoring tool could substantially strengthen pesticide risk assessments. In this work, we advocate for the inclusion of bee gut microbiota as a novel endpoint in ERA of pesticides. Using honey bees as a model, we discuss the robustness of gut microbiota as a comparative basis across laboratory and field environments. We also highlight its potential for early detection of sublethal impacts within shorter timeframes, facilitating more sensitive and cost-effective evaluations. Finally, we propose strategies to integrate microbiota-based endpoints into existing ERA frameworks and discuss recent advances and future research directions.