Esfenvalerate : Its biological activity against German cockroach, Blattella germanica (Orthoptera : Blattellidae)

Abstract

Insecticidal and knock-down activities of fenvalerate optical isomers against the German cockroach, Blattella germanica, were determined. [S, S]-isomer showed about 4times higher insecticidal and knock-down activities than racemic fenvalerate. However, the insecticidal activity of [R, S]-isomer was only one-tenth that of racemic fenvalerate, and it showed no knock-down activity. [S, R]- and [R, R]-isomers did not show insecticidal activity. Electrophysiological study showed that only [S, S]-isomer was effective against the central nervous system of the insect. These results suggested that only [S, S]-isomer was the active component of fenvalerate. It was assumed that the insecticidal activity of [R, S]-isomer was due to [S, S]-isomer contained in the [R, S]-isomer sample as impurities or [S, S]-isomer isomerized from [R, S]-isomer in the body.