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Updated: Apr 10, 2026
A Multi-detection Assay for Malaria Transmitting Mosquitoes
Published on: February 28, 2015
Knockdown resistance (kdr) mutations in Indian Anopheles culicifacies populations
Cherry L Dykes1, Raja Babu S Kushwah2, Manoj K Das3
1National Institute of Malaria Research, Sector 8, Dwarka, Delhi, India. cherry_dyke@yahoo.com.
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.
Insights
Knockdown resistance (kdr) mutations L1014F and L1014S in Anopheles culicifacies mosquitoes were found at low frequencies across India. These mutations offer protection against deltamethrin and, in the case of L1014S, DDT.
Area of Science:
- Entomology
- Molecular Biology
- Public Health
Background:
- Anopheles culicifacies mosquitoes are primary malaria vectors in India.
- Widespread resistance to DDT and emerging resistance to pyrethroids necessitate understanding resistance mechanisms.
- Knockdown resistance (kdr) mutations are crucial for insecticide resistance management due to cross-resistance.
Purpose of the Study:
- To investigate the prevalence of two kdr mutations (L1014F and L1014S) in Anopheles culicifacies populations across India.
- To assess the association of these kdr mutations with insecticide resistance to DDT and deltamethrin.
Main Methods:
- Screening of nine Anopheles culicifacies populations from five Indian states using PCR-based assays for L1014F and L1014S mutations.
- WHO insecticide susceptibility tests against deltamethrin and DDT on live and dead mosquitoes.
- Allelic association analysis to determine the impact of kdr mutations on insecticide resistance.
Main Results:
- L1014F mutation detected in most populations (except northern India) with low frequencies (0.012–0.076).
- L1014S mutation found in five central-east Indian populations with low frequencies (0.010–0.046).
- Both mutations were predominantly heterozygous and showed protection against deltamethrin; L1014S also showed protection against DDT.
Conclusions:
- The L1014F and L1014S kdr mutations coexist in some Indian populations, with L1014F being widespread except in northern regions.
- Both kdr mutations were present at low frequencies, primarily in heterozygous states.
- These kdr mutations confer protection against deltamethrin, highlighting their importance in insecticide resistance management strategies.
