Abstract
The mechanism of metabolic detoxication of parathion in the rice stem borer was examined in relation to parathion resistance.
From each of susceptible and resistant larvae, O, O-diethyl phosphorothioic acid, O, O-diethyl phosphoric acid, des-ethyl parathion, des-ethyl paraoxon and monoethyl phosphoric acid (or phosphoric acid) were detected, but there were differences in quantities of each metabolite. But there were almost equal amount of des-ethyl parathion, O, O-diethyl phosphorothioic acid and monoethyl phosphoric acid (or phosphoric acid) in the susceptible and resistant larvae. However, O, O-diethyl phosphoric acid was the predominant metabolite in the susceptible larvae while des-ethyl paraoxon was predominant in the resistant larvae. It seems that alkyl-phosphate bond of paraoxon is a “weak link” which is responsible for selective toxicity between parathion susceptible and resistant larvae of the rice stem borer.
