Objective: To investigate the sensitivity of Anopheles sinensis to DDT, cyfluthrin, malathion and deltamethrin.
Methods: In June 2009, 417, 421 and 433 mosquitoes were respectively captured from the fields of Tongbai county, Huaibin county, Yongcheng city, and tested by the adult Anopheles filter contact method recommended by WHO. The KT50 and the mortality rate of 24 h-post-exposure to 4% DDT (1.428 g/m2), 0.15% cyfluthrin (0.0 534 g/m2), 5% malathion (1.78 g/m2), 0.05% deltamethrin (0.0 178 g/m2) were calculated. The resistance level was graded as sensitive group (S) with a mortality rate of 98%-100%, preliminary resistance group (M) with mortality rate of 80%-97%, and resistance group (R) with mortality rate lower than 80%.
Results: The KT50 of An. sinensis to DDT in Tongbai, Huaibin and Yongcheng were 206.13, 877.04 and 826.81 min, respectively; the KT50 to cyfluthrin was 206.43, 85.39, and 427.60 min, respectively; the KT50 to malathion was 19.98, 48.05 and 97.79 min, respectively; the KT50 to deltamethrin was 1122.50, 89.65, and 960 min, respectively. The mortality rate of An. sinensis in 24h-post-exposure to 4% DDT was 82.52%, 57.41%, and 65.69%, and the resistance degree was judged as M, R and R, respectively. That to 0.15% cyfluthrin was 91.89%, 85.00%, and 72.73%, with a resistance degree of M, M, and R, respectively. That to 5% malathion was 95.10%, 95.37%, and 93.16%, all with a resistance degree of M. That to 0.05% deltamethrin was 92.08%, 77.14%, and 63.46%, with a resistance degree of M, R and R, respectively.
Conclusion: An. sinensis in Henan Province has developed high degree of resistance to DDT, cyfluthrin and deltamethrin, and certain degree of resistance to malathion