Neonicotinoid Retention and Transport in a Maize Cropping System with Contour Prairie Strips

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<p>Conservation areas established in agricultural fields can provide habitat for native organisms, but they also have the potential to accumulate and expose organisms to insecticides. Prairie strips are zones of cropland that have been converted to native prairie vegetation. Prairie strips increase biodiversity and reduce nutrient runoff, but they may also accumulate insecticides that endanger visiting organisms or facilitate the movement of insecticides across the landscape. In a study of paired catchments with ongoing neonicotinoid inputs, we measured the impact of prairie strips (10 % of cropland) on the accumulation and movement of the neonicotinoid insecticide clothianidin (CLO) into surface soil, deep soil, plant tissue, and groundwater across multiple slope positions during three phases of a maize growing season. While CLO accumulates in maize leaf tissue midseason following neonicotinoid application, we did not find evidence that prairie plant species in prairie strips accumulate CLO at concentrations lethal to pollinator insects. We also found that downslope soils contained the highest CLO concentrations in both catchments, showing that prairie strips did not eliminate downslope insecticide runoff. Our study adds to the existing literature examining prairie strip effects on downslope agrochemical transport, showing that when prairie strips are planted in cropland with ongoing neonicotinoid inputs, they can provide safe, low-insecticide habitat for visiting organisms amidst their other services, but may not reduce offsite insecticide runoff.</p>