Penetration and metabolism of trans-cypermethrin in a susceptible and a pyrethroid-resistant strain of Helicoverpa armigera

The pharmacokinetics of [C-14]trans-cypermethrin was studied to illustrate the differences in penetration and metabolism between a susceptible and a r esistant Thailand strain of Helicoverpa armigera (Hubner). The resistant st rain was found to possess a mechanism of reduced cuticular penetration to t rans-cypermethrin. However, the metabolism studies did not provide sufficie nt evidence of an enhanced rate of metabolism in the resistant strain. The major extractable components of feces of both the susceptible and the resis tant strains were trans-3-(2,2-dichlorovinyl)-2,2-dimethyl acid and highly polar metabolites. (C) 1999 Academic Press.