Glutathione-Dependent <i>O</i>-Alkyl and <i>O</i>-Aryl Conjugations for Dicapthon and Fenitrothion in Several Insects

Abstract

Glutathione-dependent O-alkyl and O-aryl conjugations for 24 C-dicapthon (O, O-dimethyl O-2-chloro-4-nitrophenyl phosphorothionate) and 14 C-fenitrothion (O, O-dimethyl O-3-methyl-4-nitrophenyl phosphorothionate) were studied in the each cytosolic fraction prepared from the whole bodies of the azuki bean beetle, Callosobruchus chinensis, the chestnut weevil, Curculio dentipes, the green rice leafhopper, Nephotettix cincticeps, the almond moth, Ephestia cautella, the yellow peach moth, Conogethes punctiferalis, and the rice stem borer, Chilo suppressalis. Fenitrothion was degraded almost by O-alkyl conjugation, whereas relatively high ratio of O-aryl conjugation was observed for dicapthon degradation. Particularly in the azuki bean beetle, the green rice leafhopper and the almond moth, O-aryl conjugation was dominant (60- 80%). This result is the first evidence that O-aryl conjugation is preferentially occurred for O, O-dimethyl O-aryl phosphorothionates in insects. Malpighian tubes, fat body and midgut prepared from the common cutworm, Spodoptera litura, were also assayed with 14 C-dicapthon. Interestingly, the ratios of O-alkyl and O-aryl conjugation were clearly different among the three tissues.