Conjugations of Carbaryl in Insects

Abstract

The conjugation of carbaryl and its initial breakdown products in insects has been examined. Houseflies, blowflies and grass grubs were dosed with [3 H] carbaryl and the water-soluble metabolites examined by a combination of paper chromatographic and ionophoretic techniques. These revealed the presence of 1-naphthyl dihydrogen phosphate, 1-naphtyl hydrogen sulphate and 1-naphthyl β-D-glucoside in the extracts, as well as at least seven other unidentified substances, probably including the phosphate, sulphate and glucoside conjugates of oxidation products of carbaryl. The conjugation of 1-naphthol, one of the primary metabolites of carbaryl, was examined in greater detail in flies and grass grubs. Isotope dilution and paper chromatographic analyses of extracts of insects dosed with [14 C]1-naphthol revealed the presence of the phosphomonoester, sulphate, and glucoside conjugate of 1-naphthol, but phosphodiester and glucosiduronic acid conjugates could not be detected. A new metabolite of 1-naphthol was present in extracts of dosed flies. This new metabolite, and also the corresponding p-nitrophenol metabolite, was isolated form extracts of flies fed with the parent phenols and characterised as a new conjugate, the β-D-glucoside 6-(dihydrogen phosphate). Some of the properties of this new conjugate were determined. 1-Naphthyl β-D-glucoside 6-phosphate probably accounted for one of the unidentified carbaryl conjugates.