title: Evidence of metabolic mechanisms playing a role in multiple insecticides resistance in Anopheles stephensi populations from Afghanistan.
abstract: Malaria is endemic in most parts of Afghanistan and insecticide-based vector control measures are central in controlling the disease. Insecticide resistance in the main malaria vector Anopheles stephensi from Afghanistan is increasing and attempts should be made to determine the underlying resistance mechanisms for its adequate management.
  
  
  
  The contents of cytochrome P450s, esterases, glutathione S-transferases (GSTs) and acetylcholine esterase (AChE) activities were measured in the Kunar and Nangarhar populations of An. stephensi from Afghanistan and the results were compared with those of the susceptible Beech strain using the World Health Organization approved biochemical assay methods for adult mosquitoes.
  
  
  
  The cytochrome P450s enzyme ratios were 2.23- and 2.54-fold in the Kunar and Nangarhar populations compared with the susceptible Beech strain. The enzyme ratios for esterases with alpha-naphthyl acetate were 1.45 and 2.11 and with beta-naphthyl acetate were 1.62 and 1.85 in the Kunar and Nangarhar populations respectively compared with the susceptible Beech strain. Esterase ratios with para-nitrophenyl acetate (pNPA) were 1.61 and 1.75 in the Kunar and Nangarhar populations compared with the susceptible Beech strain. The GSTs enzyme ratios were 1.33 and 1.8 in the Kunar and Nangarhar populations compared with the susceptible Beech strain. The inhibition of AChE was 70.9 in the susceptible Beech strain, and 56.7 and 51.5 in the Kunar and Nangarhar populations. The differences between all values of the enzymes activities/contents and AChE inhibition rates in the Kunar and Nangarhar populations were statistically significant when compared with those of the susceptible Beech strain.
  
  
  
  Based on the results, the reported resistance to pyrethroid and organophosphate insecticides, and tolerance to bendiocarb in the Kunar and Nangarhar populations of An. stephensi from Afghanistan are likely to be caused by a range of metabolic mechanisms, including esterases, P450s and GSTs combined with target site insensitivity in AChE.
authors.affiliation: National Malaria and Leishmania Control Programme, Ministry of Public Health, Kabul, Afghanistan.
authors.forename: Noor Halim Zahid
authors.initials: NH
authors.lastname: Safi
authors.affiliation: National Malaria and Leishmania Control Programme, Ministry of Public Health, Kabul, Afghanistan.
authors.forename: Abdul Ali
authors.initials: AA
authors.lastname: Ahmadi
authors.affiliation: National Malaria and Leishmania Control Programme, Ministry of Public Health, Kabul, Afghanistan.
authors.forename: Sami
authors.initials: S
authors.lastname: Nahzat
authors.affiliation: Student Research Committee, Department of Medical Entomology and Vector Control, Health Sciences Research Center, School of Public Health, Mazandaran University of Medical Sciences, Sari, Iran.|Department of Parasitology, North Research Centre, Pasteur Institute of Iran, Amol, Iran.
authors.forename: Seyyed Payman
authors.initials: SP
authors.lastname: Ziapour
authors.affiliation: Student Research Committee, Department of Medical Entomology and Vector Control, Health Sciences Research Center, School of Public Health, Mazandaran University of Medical Sciences, Sari, Iran.
authors.forename: Seyed Hassan
authors.initials: SH
authors.lastname: Nikookar
authors.affiliation: Department of Medical Entomology and Vector Control, School of Public Health and Health Sciences Research Centre, Mazandaran University of Medical Sciences, Sari, Iran.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Fazeli-Dinan
authors.affiliation: Department of Medical Entomology and Vector Control, School of Public Health and Health Sciences Research Centre, Mazandaran University of Medical Sciences, Sari, Iran. ahmadali_enayati@yahoo.com.
authors.forename: Ahmadali
authors.identifier: 0000-0001-6861-0719
authors.initials: A
authors.lastname: Enayati
authors.affiliation: Liverpool School of Tropical Medicine, Liverpool, UK.
authors.forename: Janet
authors.initials: J
authors.lastname: Hemingway
mesh_terms: D000346:Afghanistan; D000818:Animals; D000852:Anopheles / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D007303:Insect Vectors / Q000187:drug effects* / Q000378:metabolism; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D008288:Malaria / Q000635:transmission
chemical_list: D007306:Insecticides
keywords: Anopheles stephensi; Enzyme; Insecticide resistance; Metabolic