Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/16/1999
Publication Date: N/A
Citation: Interpretive Summary: Historically, the potential threat to human health has been the main reason for cockroach control and elimination efforts. However, within the last decade, cockroach induced asthma has been recognized as an increasingly serious problem, especially among the poor, providing additional incentive for cockroach control efforts. Surprisingly, despite nearly complete reliance on insecticides for cockroach control, sparse comparative insecticide susceptibility and detoxification data are available for the most persistent cockroach pests. Therefore, to gain a more complete understanding of the response of cockroaches to insecticides, scientists at the Center for Medical, Agricultural and Veterinary Entomology and the University of Florida quantified the susceptibility to 3 insecticide classes and measured three detoxification systems (microsomal oxidase, esterase, and glutathione S-transferase) in 8 of the major cockroach pests of humans. This research will provide basic information to the scientific community about the comparative aspects of insecticide toxicity and detoxification among cockroaches. Furthermore, through a greater understanding of the detoxification mechanisms, this research may lead to improved control strategies for these pests.
Technical Abstract: Topical bioassays using propoxur, chlorpyrifos, and lambda-cyhalothrin were conducted on eight cockroach species. Based on lethal dose values, the relative toxicities of the insecticide classes were pyrethroid > carbamate = organophoshorous. Lambda-Cyhalothrin and propoxur were more toxic toward the Blattidae as compared with the Blattellidae. The order of lambda -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 LD50 was significantly (P = 0.01; r = 0.81) correlated with glutathione S- transferase activity. Lambda-Cyhalothrin LD50 value 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).