Clothianidin is a neonicotinoid insecticide registered for use in cucurbits for soil or foliar pre-bloom applications of the crop. To understand potential risk to bees through nectar and pollen, studies have been conducted in California, U.S.A. and Ontario, Canada. In California, cucurbit plants grown on coarse, medium and fine textured soil (nine locations) were treated in 2012 and 2013 with clothianidin-containing product each year at two different application regimes, soil application at planting and soil application at BBCH growth stage of 201-229. In Ontario, the product was applied in 2013 as a foliar spray at growth stages prior to bloom at two locations. Residues of clothianidin and its major metabolites were measured in nectar and pollen, and clothianidin residues were measured in leaf tissues and soil. Based on results to date, clothianidin residues in nectar and pollen were lowest when clothianidin formulated product was applied to soil at planting. Residues of clothianidin were higher in both nectar and pollen when product was applied close to the bloom. Clothianidin residues were always lower in nectar than in pollen which is a small part of pollinator diet compared to nectar. No increase of clothianidin residues in nectar and pollen was observed after two years of continuous clothianidin formulated product use. These results suggest that multiple year use of clothianidin does not lead to increased risk of exposure to bees.

Clothianidin residues in pollen and nectar of cucurbits following different use patterns

248th National Meeting (2014)

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