Submitted to: Florida Entomologist
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/24/1998
Publication Date: N/A
Citation: Interpretive Summary: Pyrethroid insecticide toxicity can be significantly altered by changes in temperature which can lead to reduced control effectiveness in certain regions of the United States. However, the mechanism responsible for this effect has not been identified and few studies exist comparing the temperature toxicity relationship among insecticide-resistant and -susceptible insects. Therefore, scientists at the Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, have examined the effects of different temperatures on insecticide-resistant and -susceptible German cockroaches treated with a pyrethroid insecticide (lambda-cyhalothrin). They found that there was greater toxicity at lower temperatures for lambda-cyhalothrin-treated susceptible cockroaches, but not the resistant Village Green cockroaches. The resistant cockroaches exhibit a specific resistance mechanism which may be responsible for preventing the temperature-toxicity effect observed in the susceptible strain.
Technical Abstract: Pre- and post-treatment temperature effects on lambda-cyhalothrin toxicity were determined in an insecticide-susceptible and -resistant German cockroach strain. Acclimation at 19, 26, or 31 degrees C for 10 days before insecticide treatment had no effect on lambda-cyhalothrin toxicity in either strain. No differences were observed in aldrin epoxidase and glutathione-S-transferase activities when Orlando cockroaches were incubated for 10 days at 19, 26, and 31 degrees C. When temperature treatment followed insecticide application, a negative temperature coefficient of toxicity (greater toxicity at lower temperature) toward lambda-cyhalothrin was observed for the Orlando but not the kdr-type resistant Village Green cockroaches. Piperonyl butoxide synergized lambda-cyhalothrin in Orlando cockroaches 3- and 5-fold at 26 and 31 degrees C, respectively. Synergism did not occur in the Village Green strain regardless of temperature.