high insecticides resistance in culex pipiens (diptera: culicidae) from tehran, capital of iran

background: during recent years transmission of dirofilaria immitis (dog heart worm) by culex pipiens and west nile virus have been reported from iran. the present study was preformed for evaluating the susceptibility status of cx. pipiens collected from capital city of tehran, iran . methods: four insecticides including: ddt 4%, lambdacyhalothrin 0.05%, deltamethrin 0.05% and cyfluthrin 0.15 % according to who standard  methods were used for evaluating the susceptibility status of cx. pipiens from tehran moreover  for comparison susceptibility status a laboratory strain also was used.  bioassay data were ana­lyzed using probit program. the lethal time for 50% and 90% mortality (lt 50 and lt 90 ) values were calculated from regression line. results: the susceptibility status of lab strain of cx. pipiens revealed that it is susceptible to lambdacyhalothrin, deltamethrin, cyfluthrin and resistant to ddt. moreover cyfluthrin with lt 50 =36 seconds and ddt with lt 50 =3005 seconds had the least and most lt 50 s. field population was resistance to all tested insecticides and ddt yielded no mortality. conclusion: highly resistance level against all who recommended imagicides were detected in field populations. we suggest more biochemical and molecular investigations to detect resistance mechanisms in the field population for further decision of vector control.