STUDIES ON THE MODE OF ACTION OF FENVALERATE ENANTIOMERS .3. CUTICULAR PENETRATION AND METABOLISM OF FENVALERATE ENANTIOMERS IN THE GERMAN-COCKROACH, BLATTELLA-GERMANICA (L) (ORTHOPTERA, BLATTELLIDAE)

Insecticidal activity, cuticular penetration and metabolism of optical isomers of fenvalerate, R,S-S fenvalerate, (R,S) alpha-cyano-3-phenoxybenzyl (S)-2-(4-chlorophenyl)-isovalerate and R,S-R fenvalerate, (R,S) alpha-cyano-3-phenoxybenzyl (R)-2-(4-chlorophenyl)-isovalerate were studied using the German cockroach, Blatella germanica (L.). R,S-S fenvalerate was more than 3,800 times more potent than R,S-R fenvalerate. Cuticular penetration and metabolism experiments showed that [C-14] R,S-S fenvalerate penetrated more rapidly than [C-14] R,S-R fenvalerate. The patterns of in vivo metabolism of these two optical isomers were similar, showing little quantitative difference. These results showed that there was some difference in pharmacokinetic behavior between two optical isomers of fenvalerate, seemingly the result of a minor factor responsible for the difference in their bioactivities.