Neonicotinoids (NN) are the world’s most commonly used class of insecticides. Research into their environmental degradation is currently thriving due to concerns regarding their effects on non-target species, particularly pollinators, which has resulted in bans on the use of three NN in the EU and Canada. Neonicotinoids are often applied to surfaces such as seeds, vegetation and soil, and can be found on blowing dust particles. However, molecular level understanding of many of their multiphase atmospheric reactions is currently missing or incomplete. Additionally, studies to date have typically considered reactions of the pure chemical reagents. In contract, NN are applied as complex mixtures containing as little as 1% of the active ingredients mixed with emulsifiers, surfactants, and preservatives which may either suppress or enhance their surface degradation.  Here we present the results of studies aimed at identifying differences in the multiphase atmospheric degradation of formulated NN mixtures compared to the pure NN. Pure and formulated NN (e.g. nitenpyram and dinotefuran) were mixed with KBr in solid pellets and photolyzed in synthetic air or N<sub>2</sub> using three different lamps with radiation covering the range from 254 nm to ~400 nm. The NN loss with time during photolysis was followed using FTIR and reaction products were identified using UPLC-ESI-TQMS. Kinetics and degradation products for specific NN and their formulations will be compared, providing fundamental scientific understanding of the degradation processes involved and how these are sensitive to formulation matrices and environmental conditions.

Atmospheric fate of neonicotinoids as pure compounds and in formulations

2019 Fall National Meeting

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