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Background   Anopheles 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.    Methods  A 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.    Results  A 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.    Conclusion  The 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 material  The online version of this article (doi:10.1186/s12936-015-0644-0) contains supplementary material, which is available to authorized users.

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