COMPARISON OF ESTERASES BETWEEN LIFE STAGES AND SEXES OF RESISTANT AND SUSCEPTIBLE STRAINS OF GERMAN-COCKROACH (DICTYOPTERA, BLATTELLIDAE)

Esterase activity between the resistant Crawford and susceptible CSMA strains of German cockroach, Blattella germanica (L.), was compared wi th the substrates alpha- and beta-naphthyl acetate across sex and nymp hal age classes. Ester ase isozyme analysis with native polyacrylamide gel electrophoresis also was conducted to identify quantitative and q ualitative differences between strains, sexes, and age classes. The Cr awford strain was highly resistant to cypermethrin, propoxur, and perm ethrin with a resistant ratio (RR) of 17.26, 15.75, and 13.53, respect ively, and mildly resistant to chlorpyrifos (RR 5.62). The alpha-NA an d beta-NA esterase activities in the Crawford strain were significantl y higher than those activities in the CSMA strain in both nymphal and adult stages. In the Crawford strain, the enzyme activity in nymphs wa s significantly higher than that in adults, but such differences were not observed in the CSMA strain. The mobile isozymes a and c stained. more intensely than others in every developmental stage and sex of Lot h strains but showed greater intensity in the Crawford strain. Another intensely strained isozyme b was observed only in the homogenates fro m the Crawford strain. The combination of isozyme b and the overproduc ed isozyme a and c in the Crawford strain seems to be responsible for the difference in total esterase activity between the CSMA and Crawfor d strains.