A new study of pesticide use in Britain has revealed a rapid rise in toxic load for bees. The study found that despite the weight of pesticide applied halving between 1990 and 2015, the number of applications per field had almost doubled.
The research team conclude that the increasing use of neonicotinoid pesticides from 1994 onwards had given rise to a six-fold increase in the total potential kill of Honey Bees Apis mellifera. Neonicotinoids accounted for 87% of the toxic load in 2015, more than 99% of this being due to three compounds: imidacloprid, clothianidin and thiamethoxam. Despite having been banned for use on field crops, these systemic insecticides are regularly found in the pollen and nectar of both flowering crops and wild flowers.
The results suggest that risks posed by insecticides to non-target insects, such as pollinators and other beneficial insects, have increased significantly over the last quarter of a century.
The authors also draw attention to the issue of regulatory tests, which largely consist of short-term studies in which test organisms are exposed to a single chemical. There is understandable concern that this approach to testing fails to capture the risks posed by landscape-scale, industrial use of multiple pesticides.
Goulson D, Thompson J, Croombs A. (2018). ‘Rapid rise in toxic load for bees revealed by analysis of pesticide use in Great Britain.’ PeerJ, 6:e5255 https://doi.org/10.7717/peerj.5255