Historical survey of the kdr mutations in the populations of Anopheles sinensis in China in 1996–2014

Abstract

BackgroundAnopheles sinensis has become an important malaria vector in China. The long-term extensive utilization of pyrethroids for ITNs and IRS for mosquito control in the last three decades has resulted in the occurrence of resistant An. sinensis populations in many regions. Knockdown resistance (kdr), caused by point mutations in the VGSC gene, is one of the mechanisms that confer resistance to DDT and pyrethroids. Recently, several investigations revealed the kdr occurrence in some An. sinensis populations, however, no kdr data were available earlier than 2009. A survey tracking the dynamics of the kdr mutations in past decades would provide invaluable information to understand how the kdr alleles spread in mosquito populations temporally and spatially.MethodsA survey was conducted on the kdr alleles at condon 1014 of the VGSC gene and their distributions in 733 specimens of An. sinensis and 232 specimens of the other eight member species of the Anopheles hyrcanus group that were collected from 17 provinces in China in 1996–2014.ResultsA total of three kdr alleles, TTT (F), TTG (F) and TGT (C) were detected, and TGT (C) and TTT (F) were already present in the specimens from Jiangsu and Shandong as early as 1997. The TTT (F) was the most frequent mutant allele, and largely distributed in central China, namely Shandong, Jiangsu, Anhui, Henan, Shanghai, Jiangxi and Hubei. When data were analysed in three time intervals, 1996–2001, 2005–2009, 2010–2014, the prevalence of kdr alleles increased progressively over time in the populations in central China. In contrast, the kdr alleles were less frequent in the samples from other regions, especially in Yunnan and Hainan, despite the documented presence of pyrethroid resistant populations in those regions. Interestingly, no mutant alleles were detected in all 232 specimens of eight other species in the An. hyrcanus group.ConclusionThe survey revealed that the kdr occurrence and accumulation in the An. sinensis populations were more frequent in central China than in the other regions, suggesting that the kdr mutations may contribute significantly to the pyrethroid resistance in the mosquitoes in central China.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-015-0644-0) contains supplementary material, which is available to authorized users.

Bionomics and insecticide resistance of Aedes albopictus in Shandong, a high latitude and high-risk dengue transmission area in China

“…Previous studies [29,[42][43][44] only detected non-synonymous mutations in domain III (1532 and 1534) in Ae. albopictus from China.…”

First identification of kdr allele F1534S in VGSC gene and its association with resistance to pyrethroid insecticides in Aedes albopictus populations from Haikou City, Hainan Island, China

“…One of the mechanisms that mosquitoes have developed for the resistance to pyrethroids is the target insensitivity, which is caused by mutations in the VGSC gene and generated knockdown resistance ( kdr ) [ 12 – 15 ]. In Anopheles mosquitoes, substitution of leucine at residue position 1014 was correlated to the resistance to pyrethroids and DDT [ 14 – 17 ]. In Aedes aegypti Linn, mutants have been detected in several codons of the VGSC gene from different countries, including three mutants, V1016G/I and F1534C, all were correlated with kdr [ 18 – 27 ].…”

Diversity and frequency of kdr mutations within Anopheles sinensis populations from Guangxi, China

“…In An. sinensis , significant positive correlations between kdr allele frequency and bioassay-based resistance phenotype have been documented [ 16 – 19 ]. Recent years, kdr mutation has been used as a molecular mark for monitoring pyrethroid resistance in An.…”

“…Recent years, kdr mutation has been used as a molecular mark for monitoring pyrethroid resistance in An. sinensis in China [ 19 ].…”