Resistant status of Culex pipiens complex species to different imagicides in Tehran, Iran.

BACKGROUND & OBJECTIVES: Insecticides are the most important means of controlling pests in Iran especially for Culex pipiens complex species. The rational use of insecticides largely depends on understanding the susceptibility levels of these species. The study was designed to determine the susceptibility levels of Cx. pipiens complex (field and insectary strains) to various insecticides in the city of Tehran. METHODS: The mortality rates of the field strain of Cx. pipiens complex after different exposure times to DDT (4%), bendiocarb (0.1%), propoxur (0.1%), malathion (5%), fenitrothion (1.0%), permethrin (0.75%), deltamethrin (0.05%), lambda-cyhalothrin (0.05%), etofenprox (0.5%), and cyfluthrin (0.15%) were determined. The mortality rates at the lethal time 50% (LT50) and lethal time 90% (LT90) values were calculated by plotting the regression line using Microsoft Office Excel software. RESULTS: The mortality rates of the Cx. pipiens complex after 1 h exposure to the diagnostic doses of DDT (4%), bendiocarb (0.1%), propoxur (0.1%), malathion (5%), fenitrothion (1.0%), permethrin (0.75%), deltamethrin (0.05%), lambda-cyhalothrin (0.05%), etofenprox (0.5%), and cyfluthrin (0.15%) were 12, 58, 54, 82, 54, 34, 49, 40, 17, and 44%, respectively. According to the WHO classification of susceptibility levels, both field and insectary strains of Cx. pipiens complex in Tehran were resistant to these insecticides. INTERPRETATION & CONCLUSION: The results of this study showed that field Cx. pipiens complex is resistant to all the groups of insecticides used.