Metabolism of Some Carbamate Insecticides in the Green Rice Leafhopper and the Smaller Brown Planthopper

Abstract

When carbonyl-14C-labeled 3,5-xylyl methylcarbamate (XMC) and 3-tert-butylphenyl methylcarbamate (terbam) were topically applied on the adults of the green rice leafhopper, Nephotettix cincticeps Uhler, and the smaller brown plant-hopper, Laodelphax striatellus Fallen, penetration of radioactivity into the insect body was rapid. When the radioactivity taken up by insects was divided into three fractions, that is, water soluble, organosoluble, and unextracted, most of the radioactivity was found in the organosoluble fraction. Water soluble radioactivity gradually increased in course of time. Although parent compounds occupied 67-98% of organosoluble radioactivity, the ratio of metabolites gradually increased in course of time. Several metabolites were detected by tlc-radioautography. The distribution patterns of metabolites were different between the green rice leafhopper and the smaller brown planthopper. In vitro metabolism of XMC in micro-some fraction of the green rice leafhopper was accelerated by the addition of NADPH2 and was inhibited by piperonyl butoxide. Among several metabolites, N-hydroxy-methyl derivatives of the insecticides were identified. © 1978, Pesticide Science Society of Japan. All rights reserved.