Comparative insecticide susceptibility and detoxification enzyme activities among pestiferous Blattodea

Topical bioassays using propoxur, chlorpyrifos, and lambda-cyhalothrin were conducted on eight cockroach species. Based on lethal dose values, the rel ative toxicities of the insecticide classes were generally pyrethroid > car bamate > organophosphorous. lambda-cyhalothrin and propoxur were more toxic toward the Blattidae as compared with the Blattellidae. The order of lambd a-cyhalothrin toxicity was Periplaneta americana > Periplaneta brunnea = Pe riplaneta australasiae = Periplaneta fuliginosa = Blatta orientalis > Blatt ella asahinai = Blattella germanica > Blattella vaga. The order of propoxur toxicity was B. orientalis > P. americana > P. brunnea = P. australasiae>B . asahinai>P. fuliginosa=B. germanica>B. vaga. The order of chlorpyrifos to xicity was P. americana > B. asahinai = B. vaga > B. orientalis = P. austra lasiae = P. brunnea > B. germanica = P. fuliginosa. Detoxification enzyme a ctivities for each species also were measured and compared with insecticide toxicity. Propoxur LD50 was significantly (P=0.01; r=0.81) correlated with glutathione S-transferase activity. lambda-Cyhalothrin LD50 correlated wit h methoxyresorufin O-demethylase activity (P = 0.01; I = 0.81), carboxylest erase activity (P = 0.03; r = -0.75), general esterase activity (P = 0.02; I = -0.79), and cockroach weight (P = 0.01; r = -0.95). (C) 1999 Elsevier S cience Inc. All rights reserved.