title: First report of field evolved resistance to agrochemicals in dengue mosquito, Aedes albopictus (Diptera: Culicidae), from Pakistan.
abstract: BACKGROUND
  Agrochemicals have been widely used in Pakistan for several years. This exposes mosquito populations, particularly those present around agricultural settings, to an intense selection pressure for insecticide resistance. The aim of the present study was to investigate the toxicity of representative agrochemicals against various populations of Aedes albopictus (Skuse) collected from three different regions from 2008-2010.
  
  
  RESULTS
  For organophosphates and pyrethroids, the resistance ratios compared with susceptible Lab-PK were in the range of 157-266 fold for chlorpyrifos, 24-52 fold for profenofos, 41-71 fold for triazofos, and 15-26 fold for cypermethrin, 15-53 fold for deltamethrin and 21-58 fold for lambdacyhalothrin. The resistance ratios for carbamates and new insecticides were in the range of 13-22 fold for methomyl, 24-30 fold for thiodicarb, and 41-101 fold for indoxacarb, 14-27 fold for emamectin benzoate and 23-50 fold for spinosad. Pair wise comparisons of the log LC50s of insecticides revealed correlation among several insecticides, suggesting a possible cross resistance mechanism. Moreover, resistance remained stable across 3 years, suggesting field selection for general fitness had also taken place for various populations of Ae. albopictus.
  
  
  CONCLUSIONS
  Moderate to high level of resistance to agrochemicals in Pakistani field populations of Ae. albopictus is reported here first time. The geographic extent of resistance is unknown but, if widespread, may lead to problems in future vector control.
authors.affiliation: Department of Entomology, University College of Agriculture, Bahauddin Zakariya University, Multan, Pakistan. azhar_naturalist@yahoo.com
authors.forename: Hafiz Azhar Ali
authors.initials: HA
authors.lastname: Khan
authors.forename: Waseem
authors.initials: W
authors.lastname: Akram
authors.forename: Khurram
authors.initials: K
authors.lastname: Shehzad
authors.forename: Essam A
authors.initials: EA
authors.lastname: Shaalan
mesh_terms: D000330:Aedes / Q000187:drug effects*; D016573:Agrochemicals / Q000494:pharmacology*; D000818:Animals; D003715:Dengue / Q000635:transmission; D004199:Disease Vectors; D005260:Female; D007305:Insecticide Resistance; D008297:Male; D010154:Pakistan
chemical_list: D016573:Agrochemicals