Sensitivity of honey bee larvae to plant protection products and impact of EFSA bee guidance document

In addition to other assessments, the 2013 EFSA bee guidance document requires the risk assessment of plant protection products on honey bee larvae. At the time the EFSA document was finalized, no data on honey bee larvae were available. In 2013 ECPA (the European Crop Protection Association) perfomed an impact analysis of the (then) new EFSA risk assessment and the reliability of the outcomes, using estimated endpoints derived from acute oral honey bee tests together with the usual extrapolation factors. Today, a number of honey bee larvae toxicity studies have been conducted according to the newly developed testing methods for single exposure (OECD TG 237) and repeated exposure testing (OECD GD 239). These experimental data have been used to update the ECPA impact analysis. Data on 114 active substances or formulated products were used, covering 166 worst case uses; (58 herbicides, 53 fungicides, 47 insecticides and 8 PGRs). The “pass” rates were determined according to the EFSA Bee guidance document and compared with the original outcome of the impact analysis from 2013 and with adult chronic toxicity data. When the findings of the impact analysis based on experimental data from 22 day larval tests was compared with the impact analysis from 2013 based on extrapolated data the two gave very similar results, thus indicating that the original assessment using acute data and extrapolation factors was suitably predictive.