Tehran University of Medical Sciences Journal of Arthropod-Borne Diseases 2322-1984 7 1 2013 06 15 56 65 EN Aboozar Soltani Department of Medical Entomology and Vector Control, School of Public Health and National Institute of Health Research, Tehran University of Medical Sciences, Tehran, Iran. Hassan Vatandoost Department of Medical Entomology and Vector Control, School of Public Health and National Institute of Health Research, Tehran University of Medical Sciences, Tehran,Iran. Mohammad Ali Oshaghi Department of Medical Entomology and Vector Control, School of Public Health and National Institute of Health Research, Tehran University of Medical Sciences, Tehran,Iran. Ahmad Ali Enayati School of Public Health and Health Sciences Research Centre, Mazandaran University of Medical Sciences, Sari, Iran Ahmad Raeisi National Malaria Control Department, CDC, Ministry of Health and Medical Education, Iran Mohammad Reza Eshraghian Department of Medical Entomology and Vector Control, School of Public Health and National Institute of Health Research, Tehran University of Medical Sciences, Tehran, Iran Mohammad Mehdi Soltan-Dallal Department of Microbiology, School of Public Health and National Institute of Health Research, Tehran University of Medical Sciences, Tehran, Iran Ahmad Ali Hanafi-Bojd Department of Medical Entomology and Vector Control, School of Public Health and National Institute of Health Research, Tehran University of Medical Sciences, Tehran, Iran Mohammad Reza Abai Department of Medical Entomology and Vector Control, School of Public Health and National Institute of Health Research, Tehran University of Medical Sciences, Tehran, Iran Fatemeh Rafi Department of Medical Entomology and Vector Control, School of Public Health and National Institute of Health Research, Tehran University of Medical Sciences, Tehran, Iran 2015 10 16 Background: Malaria still remains a public health problem in Iran. There are different vector control interventions such as insecticide spraying. The present study was carried out to determine the susceptibility status of Anopheles stephensi larvae to temephos as a national plan for monitoring and mapping of insecticide resistance Methods: Eight different localities in two main malarious provinces were determined as field collecting sites. Mos- quitoes were collected from the field and reared in an insectray. Susceptibility assays were carried out according to the WHO method. The laboratory reared susceptible Beech-Lab strain was used for comparison. Data were analyzed using Probit analysis to determine LC50 and LC90 values. Results: Susceptibility of An. stephensi to temephos indicated that the LC50 ranged from 0.0022 mg/l to 0.0141 mg/l. Although all field strains were susceptible to temephos, considerable variations in temephos resistance ratios of field strains were noticed from all the localities studied in comparison with the susceptible strain. A low level of resistance ratio was noticed in An. stephensi populations except for the Chabahar strain (RR= 4.27 fold). All field-collected An. stephensi populations exhibited homogeneity to the larvicide except for Bandar Abbas and Hormoodar village strains (P> 0.05%). Conclusion: Due to intensive use of temephos in the neighboring countries and occurrence of resistant to this insec- ticide in the main malaria vector in the region, insecticide resistance gene may evolve in the populations of An. stephensi. If temephos be applied as a larvicide it should be used judiciously for resistance management, as rotation strategy. https://jad.tums.ac.ir/index.php/jad/article/view/256 https://jad.tums.ac.ir/index.php/jad/article/download/256/232