Tehran University of Medical Sciences Journal of Arthropod-Borne Diseases 2322-1984 4 1 2010 06 15 60 65 EN A Raeisi Malaria Control, Ministry of Health and Medical Education, Tehran, Iran MR Abai Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Iran K Akbarzadeh Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Iran M Nateghpour Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Iran M Sartipi Iranshahr Center of Public Health, Iranshahr, Iran A Hassanzehi Zahedan University of Medical Sciences, Zahedan, Iran N Shahbakhsh Zahedan University of Medical Sciences, Zahedan, Iran L Faraji Malaria Control, Ministry of Health and Medical Education, Tehran, Iran F Nikpour Malaria Control, Ministry of Health and Medical Education, Tehran, Iran M Mashayekhi Kerman University of Medical Sciences, Kerman, Iran 2015 10 03 Background: Indoor residual spraying (IRS) is functioned as national interventions against malaria in southeastern foci of Iran and deltamethrin WP one of the insecticides have been used since past decade. In this study, the residual activity of the wettable granule (WG) was studied on different surfaces in hut scale trial against Anopheles stephensi  in Iranshahr district, southeastern Iran. Methods: Three dosages of 25, 40 and 50 mg a.i./m2 of deltamethrin WG 25% formulation were applied on plaster, cement, mud, and wooden surfaces using Hudson® X-pert compression sprayer having 10 litters capacity. Results: The residual effects of deltamethrin WG 25% on different surfaces was assessed based on reduction of mortality An. stepehnsi from 100% to about 70%. At 25, 40 and 50 mg a.i./m2 the WG formulation of deltamethrin had a bioefficacy for about 2, 3 and 4 months respectively. Conclusion: There was an expectable fluctuation in mortality of An. stephensi at different sprayed surfaces as well as dosages. The proposed 50 mg/m2 WG is the longest activity for up to 4 months which needs to be applied for two spraying cycles per year at the climatically condition of southwestern Iran. https://jad.tums.ac.ir/index.php/jad/article/view/63 https://jad.tums.ac.ir/index.php/jad/article/download/63/61