Abstract
BackgroundAnopheles sinensis is a primary vector for Plasmodium vivax malaria in most regions of China. A comprehensive understanding of genetic variation and structure of the mosquito would be of benefit to the vector control and in a further attempt to contribute to malaria elimination in China. However, there is only inadequate population genetic data pertaining to An. sinensis currently.MethodsGenetic variations and structure among populations of An. sinensis was examined and analyzed based on the nucleotide sequences of a 662 nt variable region of the mitochondrial cox1 gene among 15 populations from 20 collection sites in China.ResultsA total of 453 individuals in 15 populations were analyzed. The cox1 gene sequences were aligned, and 247 haplotypes were detected, 41 of these shared between populations. The range of haplotype diversity was from 0.709 (Yunnan) to 0.998 (Anhui). The genealogic network showed that the haplotypes were divided into two clusters, cluster I was at a high level of homoplasy, while cluster II included almost all individuals from the Yunnan population. The Yunnan population displayed a significantly high level of genetic differentiation (0.452−0.622) and a restricted gene flow with other populations. The pairwise FST values among other populations were lower. The AMOVA result showed that the percentage of variation within populations (83.83%) was higher than that among populations (16.17%). Mantel test suggested that geographical distance did not significantly contribute to the genetic differentiation (R2 = 0.0125, P = 0.59). Neutral test and mismatch analysis results showed that the An. sinensis population has undergone demographic expansions.ConclusionsAnopheles sinensis populations showed high genetic polymorphism by cox1 gene. The weak genetic structure may be a consequence of low genetic differentiation and high gene flow among populations, except the Yunnan samples. The Yunnan population was isolated from the other populations, gene flow limited by geographical distance and barriers. These findings will provide a theoretical basis for vector surveillance and vector control in China.
Highlights
Anopheles sinensis is a primary vector for Plasmodium vivax malaria in most regions of China
The results suggested that geographical distance does not significantly contribute to the genetic differentiation observed in An. sinensis populations
The results showed that genetic polymorphism of An. sinensis populations have a high haplotype diversity (Hd = 0.709–0.998) and nucleotide diversity (Pi = 0.004–0.011), in turn suggesting that cox1 can be considered a suitable molecular marker for calculating genetic variation and detecting genetic structure
Summary
Anopheles sinensis is a primary vector for Plasmodium vivax malaria in most regions of China. Anopheles sinensis Wiedemann is an Oriental species with a wide distribution in China [1]. It is the primary malaria vector in plain regions of central China, especially in the paddy planting areas, and it has been identified as a pathogenic vector for other disease such as Brugia malayi, one type of lymphatic filariasis [2, 3]. The proportion of imported P. vivax malaria cases has notably increased in recent years [9, 10], and so increased knowledge on the genetic structure and the divergence among An. sinensis populations are essential to lay out effective strategies for vector control and further malarial elimination. As one important member of the Hyrcanus group, An. sinensis has been differentiated from its morphologically indistinguishable sibling species (An. lesteri, An. yatsushiroensis, and so on) by comparison of sequence data from the second internal transcribed spacer (ITS2) region of the ribosomal DNA (rDNA), which greatly facilitates the subsequent genetics study [11]
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