Extrapolating from honeybees to bumblebees in pesticide risk assessment

Bumblebees are important pollinators of many crops and wild flowers and there are both conservation and economic reasons for taking action to assess the impact of pesticides on bumblebees. Pesticide risk assessments for honeybees are based on hazard ratios which rely on application rates and toxicity data and are unlikely to be appropriate for bumblebees. Bumblebees are active at different times and on different crop species and are, therefore, likely to have different exposure profiles. Unlike honeybees, deaths of bumblebees due to pesticides are unlikely to be reported, since the bees are not kept domestically and will die in small numbers. This paper highlights the differences in the potential risk posed by pesticides to bumblebees from that of honeybees. This is based on their exposure through use of crops and flowering weeds and on available data on toxicity of pesticides. This information is also intended as a source document for information on the foraging behavior and phenology of bumblebees for use in risk assessment for pesticides.