Scientific Opinion of the EFSA Panel on Plant Protection Products and their Residues (PPR) on the science behind the development of a risk assessment of plant protection products on bees (Apis mellifera, Bombus spp., and solitary bees), EFSA Panel on Plant Protection Products and their Residues(PPR), and Vleminckx Christiane , EFSA Journal, 23/5/2012, Volume 10, Issue 5, p.2668, (2012)