Proposed decision tree to evaluate the potential risk of plant protection products to bees via succeeding crops
A data evaluation was conducted by ECPA companies to compare the acute sensitivity of the bumblebee Bombus terrestris L. with that of the honey bee Apis mellifera L. to plant protection products. For the evaluation, 97 data sets were available for oral toxicity and 108 data set for contact toxicity for both bee species. The data comprised 27 and 29 sets for oral and contact toxicity testing of fungicides, 42 and 41 for oral and contact exposure for herbicides (including one plant growth
... lant growth regulator), and 28 oral and 38 contact data sets for insecticides (including one nematicide), respectively. For data sets with definitive endpoints for honey bees (most insecticides), the sensitivity ratio (SR) was determined by dividing the honey bee LD50 by the bumblebee LD50 value. Endpoints of data sets with unbound '>' endpoints (most fungicides and herbicides) for honeybees were assigned to toxicity classes. For data sets with unbound honey bee LD50-values the data evaluation indicated similar or lower sensitivity of bumblebees versus honeybees by contact or oral exposure for all fungicides and herbicides. Likewise, similar or lower contact sensitivity of bumblebees than honey bees was determined for all insecticidal data sets (including the nematicide) with definite honeybee endpoints. For the oral exposure this was also the case except for 5 active substances. For two insecticide active ingredients the SRs were between 3.3 and 5.1. For two insecticide formulations with the same active ingredient and with unbound LD50-values for honeybees which generated SRs of approximately 95, results of higher tier semi-field data do not indicate any negative impact on B. terrestris and their colony development under more realistic semi-field conditions. Overall, the current data supports that, for a wide range of chemistry, the honey bee is a sensitive surrogate test species for bumblebees based on acute toxicity testing of plant protection products. Therefore, routine regulatory testing of the bumblebee (B. terrestris) in context of registration of plant protection products and/or using a standard safety of 10 on basis of honey bee endpoints is not justified on basis of available data review.