Options for mitigating multi-stressor interactions on managed bees in European agricultural landscapes

Managed bees provide valuable pollination services to a wide range of European crops yet they face multiple, interacting stressors including pesticides, pathogens and poor nutrition. Despite incomplete evidence, there is an urgent need to identify effective options to mitigate these stressors. Using a modified Delphi process, 21 experts ranked 29 response options across four case studies. They assessed (a) the response options ability to effectively mitigate pesticide exposure in combination with either poor nutrition or parasite load for either Apis mellifera , Bombus terrestris or Osmia bicornis and (b) the overall feasibility of implementing the response option. The scoring identified perceived effective mitigation responses, that could be prioritised to benefit multiple pollinator species facing different interacting stressors. They included flower patch creation, rewarding farmers for pollinator friendly practices, reducing spray application frequency and reducing spray drift. We also highlight ‘feasibility priorities’, where effective mitigation responses are only feasible to implement with additional targeted support. Maximising the value of currently available evidence, in combination with expert knowledge, we demonstrate a structured decision-support approach for prioritising perceived effective responses. This approach can provide evidence to help support pollinator policy and management, by bridging the current knowledge gap we have around the impacts of interacting stressors on pollinators and how to best mitigate these.