Leaching of the Neonicotinoids Thiamethoxam and Imidacloprid from Sugar Beet Seed Dressings to Subsurface Tile Drains

Abstract

Pesticide transport from seed dressings toward subsurface tile drains is still poorly understood. We monitored the neonicotinoid insecticides imidacloprid and thiamethoxam from sugar beet seed dressings in flow-proportional drainage water samples, together with spray applications of bromide and the herbicide S-metolachlor in spring and the fungicides epoxiconazole and kresoxim-methyl in summer. Event-driven, high first concentration maxima up to 2830 and 1290 ng/L for thiamethoxam and imidacloprid, respectively, were followed by an extended period of tailing and suggested preferential flow. Nevertheless, mass recoveries declined in agreement with the degradation and sorption properties collated in the groundwater ubiquity score, following the order bromide (4.9%), thiamethoxam (1.2%), imidacloprid (0.48%), kresoxim-methyl acid (0.17%), S-metolachlor (0.032%), epoxiconazole (0.013%), and kresoxim-methyl (0.003%), and indicated increased leaching from seed dressings compared to spray applications. Measured concentrations and mass recoveries indicate that subsurface tile drains contribute to surface water contamination with neonicotinoids from seed dressings.

Simultaneous determination of thiamethoxam, clothianidin, and metazachlor residues in soil by ultrahigh performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry

“…In consideration of the above-mentioned results, certain aspects should be highlighted: (i) MET was detected in 72% of the samples from herbicide-treated fields; (ii) TMX was detected in 63% of the samples from insecticide-treated fields. This finding corroborates the argument that a substantial portion of this insecticide not absorbed by the crop may accumulate in soil [25]; (iii) CLO was not detected in any of the treated soil samples, which implies that TMX was not converted to CLO in the experimental conditions.…”

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 2: impacts on organisms and ecosystems

“…Eventually, soil residues move into the aquatic ecosystems, either by percolation and leaching through the soil profile (de Perre et al 2015;Wettstein et al 2016) or in surface runoff after rainfall and storms (Chrétien et al 2017). Foliar sprays and drenches applied to orchard trees also contribute to the contamination of waterways (Englert et al 2017;Kreutzweiser et al 2008b).…”

Assessment of risk to hoary squash bees (Peponapis pruinosa) and other ground-nesting bees from systemic insecticides in agricultural soil

“…Secondly, although soilapplied neonicotinoids are known to elicit negative effects on Lepidoptera that pupate in soil 41 , Carabid beetles that live in soil at all life stages 42 , and Hexapoda, Collembola, Thysanoptera, and Coleoptera adults 43 , we could find no information on the extent to which insecticide residues in soil can pass through the cuticle or into spiracles of bees that burrow in soil. We have assumed a worst-case scenario in which all the soil residues are translocated during exposure, but this is unlikely, although neonicotinoids have relatively low organic carbon-water partition coefficients (Koc ; Table S4) 44 . However, even at 10% translocation exceedances were greater than 5% for all imidacloprid endpoints, and also for the lowest honey bee LC50 and solitary bee surrogate LC50 for clothianidin, for chronic exposure in Cucurbita crop soils,.…”