Metabolism of 14C-diazinon by gypsy moth larvae

The metabolic fate of diazinon in larvae of Porthetria dispar (L.) was determined using 14C-ring-labeled material. Following a 4-h ingestion period, 28.7 percent of the total recovered activity was present as diazinon in the larvae and 0.2 percent in the feces at 1 hr; by 12 h these amounts had changed to 1.4 and 15.4 percent, respectively. The major transformation products were 2,isopropyl-4-methyl-6-pyrimidinol greater than diazoxon greater than hydroxydiazinon greater than 2-(2'-hydroxy-2'-propyl)-4-methyl-6-pyrimidinol. Small amounts of 5 additional products were detected but were not identified. Metabolism of topically applied diazinon was the same qualitatively as that of ingested diazinon, based on a comparison of chloroform-extractable metabolites, although quantitative differences were evident. The synergists 2,6-dichlorobenzyl-2-propynyl ether (GA4-282) and piperonyl butoxide (PB) altered the metabolism of diazinon (both ingested and topical doses) by apparently similar actions, resulting in a reduction in the formation of 2-isopropyl-4-methyl-6-pyrimidinol, hydroxydiazinon, and 2-(2'-hydroxy-2'-propyl)-4-methyl-6-pyrimidinol