Study on insecticide resistance of Anopheles sinensis from Henan Province and the association with the kdr mutation

Objective To investigate the pyrethroid resistance in the malarial vector Anopheles sinensis and the association with the kdr mutation. Methods The insecticide impregnated papers contact method recommended by WHO was used to observe the knockdown rate and the mortality of Anopheles, and the Leu-Phc mutation in the sodium channel gene was detected by polymerase chain reaction and sequencing. Results Insecticide susceptibility bioassay results showed that the mortalities of Anopheles sinensis from all three localities were lower than 95% on both deltamethrin and cyfluthrin. The Anopheles sinensis had resistance to deltamethrin in Huaibin County and to deltamethrin and cyfluthrin in Yongcheng City. The mortality of Anopheles sinensis from Huaibin County tested by cyfluthrin and from Tongbai County tested by deltamethrin and cyfluthrin were between 80%-95%. There is no relationship between kdr mutation and the resistance phenotype of Anopheles sinensis to deltamethrin and cyfluthrin(χ12 = 2. 955 ,χ22 = 0. 000, P ＞ 0. 05 ). Conclusion The kdr mutation apparently does not play an important role in the pyrethroid resistance to An. sinensis, further studies are needed to determine the precise mechanisms involved. Key words: Anopheles; Resistance; Pyrethroid