Selection and characterization of temephos resistance in a population of Aedes aegypti from Tortola, British Virgin Islands

A collection of Aedes aegypti from Tortola, British Virgin Islands, with a high level of temephos resistance (46.8-fold at the 95% lethal concentratio n [LC95]) was selected to higher resistance with temephos in the laboratory . After 13 generations of pressure, the temephos resistance ratio increased to 180.6 (LC95), whereas in the absence of selection pressure the resistan ce ratio declined to 8.5. Relatively low levels of resistance or cross-resi stance to other organophosphate and carbamate insecticides, and a high leve l of resistance to the pyrethroid permethrin were also observed. Synergism tests implicated detoxifying esterases in temephos resistance and the prese nce of elevated esterase activity was confirmed by biochemical tests; howev er, no evidence was found of insensitive acetylcholinesterase. Mendelian cr osses indicated that temephos resistance was inherited as a monofactorial t rait. The presence of high levels of temephos and permethrin resistance in Ae. aegypti has important implications for Aedes control programs.