Abstract
In order to use radiolabelled benzomate for the study of permeability and metabolism of benzomate, 3H-benzomate was synthesized from 3H-dimethylsulfate and 3-chloro-2, 6-dihydroxybenzo c acid through four-reaction steps. The yield of synthesized 3H-benzomate was 81.3% and its specific activity was 1.09m Ci/mmol. Female adults of five citrus red mite strains were dipped in 200ppm solution of 3H-benzomate for 5sec. At 24hr after treatment, 17, 41, 49, 60 and 66% of the dose applied had penetrated through the cuticle of the Okitsu R, Shizuoka R, Fukuoka R, Shizuoka S and Fukuoka S strains, respectively. It was suggested that in the Okitsu R strain, the low rate of benzomate permeability through the cuticle was one of the mechanisms of benzomate resistance in citrus red mite. Metabolites of five strains of citrus red mite were compared 24hr after dipping in 200ppm solution of 3H-benzomate. About 60 to 75% of the 3H-benzomate applied was recovered as benzomate itself from each strain of mites. The main metabolite was ethyl-3-chloro-2, 6-dimethoxybenzohydroxamate. There was a slight difference in the metabolism among the five strains. It is suggested that the metabolism of benzomate may not be an important factor of benzomate resistance in the citrus red mite.
