The metabolism of cypermethrin in plants: The conjugation of the cyclopropyl moiety

The metabolism of the pyrethroid insecticide cypermethrin (S,R,]-α-cyano-3-phenoxybenzyl-(1R,1S,cis,trans)-2,2-dimethyl-3-(2′,2′-dichlorovinyl)cyclopropane carboxylate), I, has been examined in lettuce plants grown and treated twice under outdoor conditions with ¹⁴C-cyclopropyllabeled material. The application rate at each treatment was equivalent to 0.3 kg/ha. At harvest, 21 days after the last application, the plants contained mainly unchanged cypermethrin (33% of the total radiolabel present) and polar materials (54%) which were shown to be conjugates of trans-2(2′,2′-dichlorovinyl)-3,3-dimethylcyclopropane carboxylic acid (II). One of these was identified as the β,d-glucopyranose ester. In separate experiments the uptake and metabolism of the acid (II) in cotton leaves were examined in the laboratory and the acid was shown to be readily converted into a mixture of the β,d-glucopyranose ester, an acidic derivative of this, and disaccharide derivatives including the glucosylarabinose ester and the glycosylxylose ester. Subsequently, cotton leaves were exposed to solutions of these individual conjugates, and interconversions between these metabolites were observed.