Background: Culex mosquitoes are important vectors of several human pathogens, like West Nile Virus.
Culex pipiens is an urban nuisance species and considered as one of the main species in public health control programs. Insecticides are the primary tools for controlling mosquitoes in Iran, especially Cx. pipiens complex species.
Tehran locality has been depending on the use of chemical insecticides as the principal method of control of mosquitoes for more than 20 years.Objectives: The aim of this study was to determine the susceptibility status in Cx.pipiens species to malathion, chlorpyrifos and temphos larvicides.Materials and Methods: Mosquito larvae, collected from different breeding sites in southern Iran, sites were located in the same climatic area with a slight difference. These larvae were reared under conditions at a temperature of 25 °C and 70% (±5%) RH with a 12:12h light: dark photoperiod, in
Tehran University of Medical Science laboratory. Early fourth instars larvae were tested against malathion,
Chlorpyrifos and temphos larvicides. The larval bioassay was conducted based on the standard WHO test protocol. Different concentrations in larvicides were used in this bioassay based on 10%–90% mortality. The mortality of larvae was observed after 24 h and were compared the LC50 values field strains with lab strains.Results: Based on present study, the Cx. pipiens is predominant in southern of Tehran. For larval bioassay, the log dose/probit mortality relationships for each larvicides tested separately were well fitted by straight lines (P> 0.05). The LC50 values were determined as 4mg/L, 0.04mg/L and 0.10mg/L in field strains and 3mg/L, 0.03mg/L and 0.09mg/L in lab strain for malation, chlorpyrifos and temphos larvicides, respectively.Conclusion:
Susceptibility of the field population of Cx. pipiens in
Tehran was performed against malathion, chlorpyrifos and temphose larvicides which the population of Cx. pipiens is still sensitive to common larvicides. Therefore, it seems appropriate to consider using such larvicides for the vector control. Furthermore, a regularly use of larvicide coupled with arranged monitoring of insecticide resistance is recommended to decreasing the rapid emergence of insecticide resistance.