New experiences and insights of two-year testing with the leafcutter bee Megachile rotundata in a semi-field test design

According to the revised Draft EFSA Bee Guidance Document (EFSA 2023), a key area of concern is the potential risk posed to wild pollinator bee species by the application of plant protection prod-ucts (PPPs). This information holds significant importance due to the limited understanding of wild bee species' exposure. Non-Apis bees comprise a wide range of body sizes as well as biological and life history traits which may result in differences in sensitivity and exposure routes in comparison to honey bees. In the EFSA Bee GD (EFSA 2023) it was advised to consider not only honey bees, but also solitary bees in the plant protection product risk assessment. Authorities require such data to conduct thorough risk assessments for non-Apis bees. Consequently, the ICPPR non-Apis working group has developed a study protocol focusing on the solitary red mason bee Osmia bicornis L., along with recommendations for a standardized Tier II test design (Franke et al 2021). Given the distinct exposure pathways and life-history traits between the solitary bee Osmia bicornis and the alfalfa leafcutter bee Megachile rotundata, it is anticipated that the same PPPs may affect these species differently (Sgolastra et al 2019). In addition, a higher sensitivity of Megachile species to selected PPPs due to a lower detoxification ability was estimated (Hayward et al 2019). The primary aim of the two-year tests, conducted in Spain, was the methodological development of a standardised Tier II study semi-field test design based on the recommended protocol for O. bicornis and to include scenarios for other potential routes of exposure for non-Apis bees towards PPPs to account for these data gaps and uncertainties in a regulatory context and to provide further solutions for the reliability of risk assessment for solitary bees.