Metabolism of the insecticide SD 8280, 2-chloro-1-(2,4-dichlorophenyl)vinyl dimethyl phosphate,following its application to rice

The metabolism of the insecticide SD 8280 2-chloro-1-(2,4-dichlorophenyl)vinyl dimethyl phosphate] in rice plants has been examined. When rice seedlings were treated with ¹⁴C]-SD 8280 the major metabolite was 1-(2,4-dichlorophenyl)ethanol which was present mainly conjugated with plant carbohydrates. This compound was also the major metabolite present in grain and straw from rice treated with ¹⁴C]-SD 8280 and grown to maturity under paddy conditions both in the glasshouse and in an outdoor enclosure. Other metabolites detected in the mature plants included 2-chloro-1-(2,4-dichlorophenyl)vinyl methyl hydrogen phosphate and 2,4-dichloro-benzoic acid, both of which occurred in free and conjugated forms. Paddy water was sampled at intervals after the application of ¹⁴C]-SD 8280 and the total residue in the water fell from initial levels of 0.28–1.1 μg/ml (expressed as SD 8280 equivalent) immediately after treatment to <0.01 μg/ml after 2–3 weeks. The total residues in the soil from these experiments were low and did not exceed 0.20 mg/kg (SD 8280 equivalents) through the 0–15 cm profile.