The colonization of pyrethroid resistant strain from wild Anopheles sinensis, the major Asian malaria vector.

Guoding Zhu,Qi Gao,Yaobao Liu,Yaping Gu,Julin Li,Sui Xu,Yuanyuan Cao,Jianxia Tang,Feng Lu,Chao Zhang,Weiming Wang,Jun Cao,Huayun Zhou,Liang Bai

doi:10.1186/s13071-014-0582-7

Abstract

BackgroundAnopheles sinensis is one of the most important malaria vectors in Asian countries. The rapid spread of insecticide resistance has become a major obstacle for insecticide-based strategies for vector control. Therefore, it is necessary to prepare an insecticide-resistant strain of An. sinensis to further understand the insecticide resistance mechanisms in this species to facilitate genetic approaches to targeting the insecticide-resistant population of this important malaria vector.MethodsAn. sinensis mosquitoes were collected from regions where pyrethroid resistance had been reported. The mosquitoes were subjected to continuous pyrethroid selection after species confirmation, and the forced copulation method was used to increase the mating rate. In addition, the knockdown-resistance (kdr) mutation frequencies of each generation of An. sinensis were measured; and the metabolic enzyme activities of cytochrome P450 monoxygenases (P450s) and glutathione S-transferases (GSTs) were detected.ResultsThe identification of field-captured An. sinensis was confirmed by both morphological and molecular methods. The population of An. sinensis exhibited stable resistance to pyrethroid after continuous generations of pyrethroid selection in the laboratory with high kdr mutation frequencies; and elevated levels of both P450s and GSTs were significantly found in field selected populations comparing with the laboratory susceptible strain. So far, the colonised strain has reached its eleventh generation and culturing well in the laboratory.ConclusionsWe colonised a pyrethroid-resistant population of An. sinensis in the laboratory, which provides a fundamental model for genetic studies of this important malaria vector.

Highlights

Anopheles sinensis is one of the most important malaria vectors in Asian countries
Pyrethroid resistance selection Male and female F1 An. sinensis mosquitoes were separately tested with a standard World Health Organization (WHO) bioassay, and the resistance status of both sexes was classified as “Resistant”
The establishment of resistant strains is essential for further understanding the mechanism of the development of insecticide resistance among insects, including anopheles mosquitoes; the colonised resistant strains could be used in testing new malaria interventions/tools that might counter physiological resistance among these vector species

Summary

Introduction

Anopheles sinensis is one of the most important malaria vectors in Asian countries. The rapid spread of insecticide resistance has become a major obstacle for insecticide-based strategies for vector control. Anopheles sinensis (Diptera, Culicidae) is one of the major malaria vector mosquitoes in China and other Asian countries [1,2,3,4]. This species is an important member of the An. hyrcanus group (Diptera, Culicidae) with similar morphology [5]. The substantial increase in pyrethroid-based malaria vector control in the past decade has resulted in the rapid spread of resistance among malaria vectors. High-level resistance to pyrethroids has been reported in An. sinensis, especially in central China, in recent years, which has placed current national efforts of malaria elimination at risk [11]. Improvements to the surveillance of and response to insecticide resistance in An. sinensis in China are urgently needed and must be based on a greater understanding of the molecular mechanisms underlying this resistance

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