Neonicotinoids comprise a broad group of insecticides that are widely used in agricultural seed coat treatments. Studies have shown that neonicotinoids can affect pollinator longevity and behavior. Neonicotinoids may persist in agricultural soils that have been taken out of production. Dispersion of neonicotinoid residues generated during sowing and plowing could contribute to pesticide drift into non-agricultural ecosystems, which poses a threat to pollinator populations in these habitats. To assess the effects of neonicotinoid drift, we carried out a two-month field study using sticky traps to collect airborne dust that settled in to pollinator habitat restorations embedded in an agricultural landscape. We also collected soil cores from these sites at the beginning and ending of the study to estimate the neonicotinoid turnover at four different depths: 0 -5 cm, 5-10 cm, 10-20 cm, and 20-30 cm. We examined the level of three different neonicotinoids (clothianidin, thiamethoxam, and imidacloprid) in soil cores and dust collected in our study sites based on LC-MS/MS analysis.
Results/Conclusions
We found neonicotinoid residues in 98.6% of soil samples from restored pollinator habitats. The mean total neonicotinoid residue was 1.49 (range 0 to 7.63) ng/g. We also observed the accumulation of neonicotinoid residues in the soil surface over the course of the spring planting season, with higher average accumulation rates of neonicotinoids in the 0 -5 cm soil cores when compared to soils at depth. Furthermore, we detected neonicotinoid residues in our dust samples, although the amount of neonicotinoids in dust varied greatly over time and from site to site. Nevertheless, the presence of neonicotinoids in dust suggests that drift is an input source of neonicotinoids to the environments adjacent to agricultural areas.