Comparative insecticide susceptibility and detoxification enzyme activities among pestiferous Blattodea

Abstract

Topical bioassays using propoxur, chlorpyrifos, and λ-cyhalothrin were conducted on eight cockroach species. Based on lethal dose values, the relative toxicities of the insecticide classes were generally pyrethroid>carbamate>organophosphorous. λ-Cyhalothrin and propoxur were more toxic toward the Blattidae as compared with the Blattellidae. The order of λ-cyhalothrin toxicity was Periplaneta americana> Periplaneta brunnea= Periplaneta australasiae= Periplaneta fuliginosa= Blatta orientalis> Blattella 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 toxicity was P. americana> B. asahinai= B. vaga> B. orientalis= P. australasiae= P. brunnea> B. germanica= P. fuliginosa. Detoxification enzyme activities for each species also were measured and compared with insecticide toxicity. Propoxur LD 50 was significantly ( P=0.01; r=0.81) correlated with glutathione S-transferase activity. λ-Cyhalothrin LD 50 correlated with methoxyresorufin O-demethylase activity ( P=0.01; r=0.81), carboxylesterase activity ( P=0.03; r=−0.75), general esterase activity ( P=0.02; r=−0.79), and cockroach weight ( P=0.01; r=−0.95).