Abstract
The fates of 2-sec-butylphenyl methylcarbamate (carbonyl-14C) [BPMC] and o-cumenyl methylcarbamate (carbonyl-14C) [MIPC] were studied on and in green rice leafhopper. Two strains of the hoppers of different susceptibilities to the carbamate insecticides were used in the present study: Chikugo strain showing the LD50 values of 26.8 (BPMC) and 20.0 (MIPC), and Shinwa strain showing 105.7 and 104.8, respectively. Acetone solution of the 14C-ladelled carbamate was applied topically on the thoracic region of adult females. A rather high rate of penetration was observed, which suggested to be a factor on the fast-acting property of phenyl methycarbamate to the hoppers. The penetration rate, however, showed no difference between Chikugo and Shinwa strains. More than 97% of radioactivity soluble in the organic solvent was due to the intact compound, and its TLC showed little difference between the strains. The concentration of BPMC or MIPC in a whole insect body, calculated from the detected amount, corresponded with I50 value to ChE activity in a susceptible strain of the hoppers. Radioactivity in the water-soluble and unextractable fraction was higher in Chikugo strain in Shinwa strain. It suggest therefore that different metabolism of these methylcarbamates occur between two strains.
