Two decades of spatial and temporal pesticide risk to non-target invertebrates in England farmlands

Pesticide impact assessment methods provide relevant approaches to quantifying risks to non-target terrestrial biodiversity in agricultural systems. Here we develop such an approach through combined analysis of pesticide usage, cropping patterns and ecotoxicological hazard datasets to generate a temporal series of maps (1994–2016) of the spatial risk of pesticides for invertebrates in England. Using data for 179 insecticides, fungicides and herbicides applied on arable crops, we assessed how pesticide risk for bees, earthworms, springtails, parasitic wasps and lacewings varied in space and time over two decades of usage shift. Change in the extent of risk associated with annual applied pesticide amounts differed depending on the organism examined. Organophosphates, pyrethroids, organochlorines and neonicotinoids all contributed to risk in bees. Insecticides, fungicides and herbicides all contributed to risk in springtails. Unexpectedly herbicides (particularly chlorotoluran) had the largest contribution to risk in lacewings, albeit with some uncertainty. Insecticides (particularly organophosphates) made the greatest contribution to risk in parasitic wasps. For earthworms, fungicides (particularly triazole fungicides and the diarylamine fluazinam) were important for risk. A noteworthy finding was that temporal risks linked to pesticide usage have changed only modestly from 1994 to 2016, despite the changes in approved authorisations and key policy such as the removal from use of most members of the neonicotinoid class of insecticides. We discuss how insights, particularly those relating to the magnitude of risk, should be considered in future studies, and how the provision of higher resolution usage data and better hazard information could improve past and future pesticide risk understanding.