IN VIVO FATE OF INSECTICIDE ZECTRAN IN SPRUCE BUDWORM TOBACCO BUDWORM AND HOUSEFLY LARVAE

The insecticide Zectran (4-dimethylamino-3,5-xylyl methylcarbamate) was tested on spruce budworm, tobacco budworm, and housefly larvae. It is highly toxic to spruce budworm larvae, but considerably less toxic to the other two larval insects. Differences were found in the location of activity and rate of metabolism of Zectran among the three insects studied. After topical treatment Zectran was metabolized to at least nine metabolites in the spruce budworm and tobacco budworm and 10 in the housefly. The identity of four of the major metabolites was established by cochromatography and the use of radioactive Zectran labeled in the carbonyl or dimethyl-C14-amino positions. These four metabolites were found in all three insects. In order of occurrence and in decreasing concentration they were: 4-methylamino-3,5-xylyl methylcarbamate, 4-amino-3,5-xylyl methylcarbamate, 4-methylformamido-3,5-xylyl methylcarbamate, and 4-formamido-3,5-xylyl methylcarbamate. One additional metabolite was tentatively identified as 4-dimethylamino-3,5-xylyl-N-hydroxymethyl carbamate. Hydrolysis of Zectran was not observed, as indicated by a lack of C14O2 evolution. Oxidation of Zectran on the surface of the spruce budworm cuticle may be a major source of the metabolites found in the homogenates. The rate of cuticular penetration was much the same for all three insects until the third hour. © 1969, American Chemical Society. All rights reserved.