Data from: A nation-wide survey of neonicotinoid insecticides in agricultural land with implications for agri-environment schemes

1. Neonicotinoids are the most widely used class of insecticides globally.
However, the link between farming practices and the extent of
contamination of soils and crops by neonicotinoid insecticides, as well as
and the extent of such contamination in organic fields and ecological
focus areas (EFAs) are currently unclear. 2. We measured the
concentrations of five neonicotinoid insecticides (imidacloprid,
clothianidin, thiamethoxam, thiacloprid, acetamiprid) in 702 soil and
plant samples in 169 cultivated fields and EFAs from 62 conventional,
integrated production and organic farms distributed over the entire
lowland of Switzerland. 3. We detected neonicotinoids in 93% of organic
soils and crops, and more than 80% of EFA soils and plants – two types of
arable land supposedly free of insecticides. We also tested 16 samples of
organic seeds, of which 14 were positive for neonicotinoids. 4. Finally,
we calculated hazard quotients (HQs) and potentially affected fractions
for 72 beneficial and 12 pest species. Under a field-realistic scenario,
we found that between 5.3 and 8.6% of above-ground invertebrate species
may be exposed to lethal concentrations of clothianidin, and 31.6 to 41.2%
to sublethal concentrations, in “integrated production” and conventional
fields. We also found that 1.3 to 6.8% (up to 12.5% based on HQs) of the
beneficial invertebrate species may be exposed to sublethal concentrations
of neonicotinoids in EFAs and organic fields. In contrast, no pest species
would be exposed to lethal concentrations, even under a worst-case
scenario. 5. Synthesis and applications. Our study suggests that diffuse
contamination by neonicotinoids may harm a significant fraction of
non-target beneficial species. The use of neonicotinoids on crops may
threaten biodiversity in refuge areas, while also potentially jeopardizing
the practice of organic farming by impeding the biological control of
pests. Based on our results, we call for a reduction in the dispersion and
overuse of neonicotinoid insecticides in order to prevent any detrimental
effects on biodiversity and ecosystem services associated with
agroecosystems.