title: Knockdown resistance (kdr) mutations in Indian Anopheles culicifacies populations.
abstract: BACKGROUND
  Anopheles culicifacies s.l. is one of the primary vectors of malaria in India responsible for the highest number of malaria cases. This vector is resistant to DDT in most parts of the country with indication of emerging resistance to pyrethroids. Since knockdown resistance (kdr) is known to confer cross-resistance between DDT and pyrethroids owing to a common target site of action, knowledge of prevalence of knockdown resistance (kdr) alleles is important from insecticide resistance management point of view.
  
  
  METHODS
  Nine populations of An. culicifacies belonging to five states of India, representing northern, western and central-east India, were screened for the presence of two alternative kdr mutations L1014F and L1014S using PCR-based assays. Dead and alive mosquitoes, following WHO standard insecticide susceptibility test against deltamethrin and DDT, were tested for allelic association.
  
  
  RESULTS
  L1014F mutation was recorded in all populations studied except from Haryana and Rajasthan states in northern India, with low frequencies ranging between 0.012 and 0.076; whereas presence of L1014S mutation was recorded in five populations only belonging to central-east India, with allelic frequencies ranging between 0.010 and 0.046. Both the kdr mutant alleles were found mostly in heterozygous condition without deviating from Hardy-Weinberg equilibrium. Both mutations showed protection against deltamethrin whereas only L1014S mutation showed protection against DDT when tested using additive model.
  
  
  CONCLUSIONS
  The two L1014-kdr mutations, L1014F and L1014S, co-occurred in five populations belonging to Chhattisgarh and Odisha states of India whereas L1014F was present in all populations studied except populations from northern states. Both kdr mutations were found with very low allelic frequencies mostly in heterozygous condition and exhibited protection against deltamethrin.
authors.affiliation: National Institute of Malaria Research, Sector 8, Dwarka, Delhi, India. cherry_dyke@yahoo.com.
authors.forename: Cherry L
authors.initials: CL
authors.lastname: Dykes
authors.affiliation: National Institute of Malaria Research, Sector 8, Dwarka, Delhi, India. kushwah001@gmail.com.
authors.forename: Raja Babu S
authors.initials: RB
authors.lastname: Kushwah
authors.affiliation: National Institute of Malaria Research Field Unit TB Sanatorium complex, Itki, Ranchi, India. manojdas2003@yahoo.co.in.
authors.forename: Manoj K
authors.initials: MK
authors.lastname: Das
authors.affiliation: National Institute of Malaria Research Field Unit, RLTRI campus, Raipur, India. sn.sharma07@rediffmail.com.
authors.forename: Shri N
authors.initials: SN
authors.lastname: Sharma
authors.affiliation: National Institute of Malaria Research Field Unit, RLTRI campus, Raipur, India. rmbhatt@rediffmail.com.
authors.forename: Rajendra M
authors.initials: RM
authors.lastname: Bhatt
authors.affiliation: Defence Research Laboratory, Tezpur, Assam, India. vijayveer50@yahoo.com.
authors.forename: Vijay
authors.initials: V
authors.lastname: Veer
authors.affiliation: School of Studies in Zoology, Jiwaji University, Gwalior, India. op_agrawal51@rediffmail.com.
authors.forename: Om P
authors.initials: OP
authors.lastname: Agrawal
authors.affiliation: National Institute of Malaria Research, Sector 8, Dwarka, Delhi, India. adak.mrc@gmail.com.
authors.forename: Tridibes
authors.initials: T
authors.lastname: Adak
authors.affiliation: National Institute of Malaria Research, Sector 8, Dwarka, Delhi, India. singh@mrcindia.org.
authors.forename: Om P
authors.initials: OP
authors.lastname: Singh
mesh_terms: D000483:Alleles; D000818:Animals; D000852:Anopheles / Q000187:drug effects* / Q000235:genetics*; D007194:India; D019476:Insect Proteins / Q000235:genetics*; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D020125:Mutation, Missense; D009570:Nitriles / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D011722:Pyrethrins / Q000494:pharmacology; D015222:Sodium Channels / Q000235:genetics*
chemical_list: D019476:Insect Proteins; D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; D015222:Sodium Channels; C017180:decamethrin