‘Focal species’ – can this well-known concept in higher-tier risk assessments be an appropriate approach for solitary bees?

Bumble bees and solitary bees have to be considered in addition to honey bees regarding environmental pollinator risk assessments. For solitary bees it is proposed to use Osmia cornuta (LATR., 1805) or O. bicornis (L., 1758) as test organisms. Whereas for higher-tier assessments, semi-field testing of solitary bees has been proved to obtain sound results, experience from current Osmia field studies show that exposure of adults and larvae is not necessarily the case due to the pronounced polylectic feeding behaviour. As an alternative refinement option the ‘focal species’ concept may be used, which is well-known as a kind of first step for higher tier bird and mammal risk assessments. This approach as it applies to solitary bees, as well as its needs, refinement options and limitations is presented.