The polymorphism and the geographical distribution of the knockdown resistance (kdr) of Anopheles sinensis in the Republic of Korea

Abstract

BackgroundIn the Republic of Korea (ROK), six sibling species of the Anopheles sinensis complex are considered the vector species of malaria, but data on their susceptibilities to malaria and vector capacities have been controversial. The intensive use of insecticides has contributed to the rapid development and spread of insecticide resistance in the An. sinensis complex. Knockdown resistance (kdr) to pyrethroids and DDT in the An. sinensis complex is associated with a mutation in codon 1014 of the voltage-gated sodium channel (VGSC) gene. Because the degree of insecticide resistance varies among mosquito species and populations, the detection of kdr mutations among the six sibling species of the An. sinensis complex is a prerequisite for establishing effective long-term vector control strategies in the ROKMethodsIn order to investigate species-specific kdr mutations, An. sinensis complex specimens have been collected from 22 sites in the ROK. Because of the difficulties with species identifications that are based only on morphological characteristics, molecular identification methods have been conducted on every specimen. Part of the IIS6 domain of the VGSC was polymerase chain reaction-amplified and directly sequenced.ResultsThe molecular analyses revealed that mutations existed at codon 1014 only in An. sinensis sensu stricto and no mutations were found in the other five Anopheles species. In An. sinensis s.s., one wild type (TTG L1014) and three mutant types (TTT L1014F, TTC L1014F, and TGT L1014C) of kdr alleles were detected. The TTC L1014F mutation was observed for the first time in this species.ConclusionsThe fact that the highly polymorphic kdr gene is only observed in An. sinensis s.s., out of the six Anopheles species and their geographical distribution suggest the need for future studies of insecticide resistance monitoring and investigations of species-specific resistance mechanisms in order to build successful malaria vector control programmes in the ROK.

Relationship between Knockdown Resistance, Metabolic Detoxification and Organismal Resistance to Pyrethroids in Anopheles sinensis

“…We did not detect any L1014S mutation as previously reported in An. sinensis populations from the Republic of Korea and Vietnam [17], [31], [47], [48]. Regarding metabolic detoxification mechanisms of resistance, GST activity was not detected as a significant variable associated with deltamethrin resistance in the multiple regression analyses.…”

L1014F-kdr Mutation in Indian Anopheles subpictus (Diptera: Culicidae) Arising From Two Alternative Transversions in the Voltage-Gated Sodium Channel and a Single PIRA-PCR for Their Detection

“…Leucine-to-phenylalanine mutation at residue L1014 is the most common mutation reported in insects including anophelines (Davies and Williamson 2009), mostly because of A>T substitution on the third codon position of residue L1014 (TTA) except in Anopheles sinensis Wiedemann (Kang et al 2012). Here, we report presence of two coexisting alternative point mutations in An.…”

“…In all anophelines reported so far, except in An. sinensis (Kang et al 2012), the L1014 is coded by TTA, where the L1014F-kdr substitution is known to be conferred by A>T mutation on third codon position. The other possible alternative nucleotide substitution leading to L1014F mutation is A>C, which is very uncommon in insects and has not been reported earlier in any anopheline.…”

Preliminary report of knockdown resistance in Culex pipiens pallens and Aedes koreicus from Korea

“…Although insecticide resistance research on Anopheles mosquitoes in Korea has been active (Kim et al 2007b;Kang et al 2012;Choi et al 2016), studies on Aedes and Culex mosquitoes are few. In the same genus, Aedes aegypti and Aedes albopictus have been frequently studied for insecticide resistance.…”