Tehran University of Medical Sciences Journal of Arthropod-Borne Diseases 2322-1984 12 3 2018 09 30 310 320 Mohammad Amin Gorouhi Department of Vector Biology and Control, School of Health, Kerman University of Medical Sciences, Kerman, Iran AND Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Mohammad Ali Oshaghi Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Hassan Vatandoost Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran AND Department of Chemical Pollutants and Pesticides, Institute for Environmental Research, Tehran University of Medical Sciences, Tehran, Iran Ahmad Ali Enayati Department of Medical Entomology, Mazandaran University of Medical Sciences, Sari, Iran Mohamad Reza Abai Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran AND Department of Chemical Pollutants and Pesticides, Institute for Environmental Research, Tehran University of Medical Sciences, Tehran, Iran Mohsen Karami Infectious Diseases and Tropical Medicine, Babol University of Medical Sciences, Babol, Iran Yaser Salim-Abadi Department of Health Service and Health Promotion, School of Health, Rafsanjan University of Medi-cal Sciences, Rafsanjan, Iran Ahmad Ali Hanafi-Bojd Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran AND Department of Chemical Pollutants and Pesticides, Institute for Environmental Research, Tehran University of Medical Sciences, Tehran, Iran Abbas Aghaei-Afshar Department of Vector Biology and Control, School of Health, Kerman University of Medical Sciences, Kerman, Iran Azim Paksa Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Fatemeh Nikpoor Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran AND Department of Chemical Pollutants and Pesticides, Institute for Environmental Research, Tehran University of Medical Sciences, Tehran, Iran 2018 09 30 Background: Anopheles stephensi is a key urban malaria vector in the Indian subcontinent and Middle East includ­ing south and southeast of Iran. Wide application of insecticides resulted in resistance of this species to various insec­ticides in these regions. This study was conducted to reveal the role of metabolic mechanisms in the development of resistance in An. stephensi to DDT and cyfluthrin. Methods: Field mosquito specimens were collected from Chabahar Seaport, southeast corner of Iran, in 2015. Insec­ticide susceptibility and enzyme assays were conducted as recommended by WHO. Results: Mean enzyme ratios were 3.95 and 3.04 for α- esterases and 2.40 and 1.97 for β- esterases in the DDT and cyfluthrin- resistant populations correspondingly compared with the susceptible strain. The GSTs enzyme mean ac­tivity ratios were 5.07 and 2.55 in the DDT and cyfluthrin- resistant populations compared with the susceptible beech strain. The cytochrome p450s enzyme ratios were 1.11 and 1.28 in the DDT and cyfluthrin- resistant populations respectively compared with the susceptible beech strain. Conclusion: Metabolic mechanisms play a crucial role in the development of DDT and cyfluthrin resistance in An. stephensi, therefore, further evaluation of the mechanisms involved as well as implementation of proper insecticide resistance management strategies are recommended. https://jad.tums.ac.ir/index.php/jad/article/view/985 https://jad.tums.ac.ir/index.php/jad/article/download/985/415