1993 Volume 44 Issue 3 Pages 263-269
Resistance of Culex tritaeniorhynchus in Okinawa Prefecture to insecticides was investigated between 1970 and 1972,and in 1989. The mosquitoes collected from 8 localities in Okinawajima between 1970 and 1972 were resistant to organochlorines, p, p'-DDT, lindane and dieldrin, but those from a few localities were susceptible to 6 organophosphates except malathion and naled. The LC_<50> values of these strains were 0.012-0.61ppm for p, p'-DDT, 0.23-0.26ppm for lindane, 0.18-0.31ppm for dieldrin, 0.05-0.84ppm for malathion, and 0.036-0.26ppm for naled. However, in 1989,the species in Okinawajima and Ishigakijima was susceptible to p, p'-DDT, but resistant to organophosphates, especially malathion, fenitrothion, fenthion and temefos with LC_<50> values of 12.2-25.0,1.78-2.50,3.90-4.58 and 4.43-4.44ppm, respectively. The species was also resistant to propoxur (a carbamate) with LC_<50> value of 3.82-5.05ppm but susceptible to permethrin, a pyrethroid, with LC_<50> value of 0.0065-0.0072ppm.
