Objective: To understand the sensitivity of Anopheles sinensis to deltamethrin, DDT and malathion in Jiangsu province.
Methods: The adult mosquitoes were captured from the fields of Sihong, Yangzhong and Yixing counties (cities) and cultured, and by using the method recommended by WHO, their first filial generations knocked down at 10, 15, 20, 30, 40, 50, and 60 min after exposure with insecticides aforementioned were counted, and the mortality of mosquitoes tested after 24 h was recorded.
Results: The knock down rates of mosquitoes, which were the first generation (F0) of Anopheles sinensis captured from the field of Sihong, Yangzhong, Yixing counties (cities) to 0.05% deltamethrin were 28.57%, 57.14%, 52.38%, respectively 60 min after the exposure; and the mortality rates 24 h-post-exposure were 35.71%, 57.14%, 61.90%, respectively. The resistance degree to deltamethrin was assessed as "R" level. The knock down rates of mosquitoes 60 min after the exposure to 4% DDT were 9.52%, 2.38%, 4.76%, respectively, and the mortality rates 24 h-post-exposure were 47.62%, 50.00%, 40.48%, respectively. The resistance degree to DDT was assessed as "R" level. The knock down rates of mosquitoes 60 min after the exposure to 5% malathion were 11.90%, 28.57%, 28.13%, respectively, and the mortality rates 24 h after the exposure were 80.95%, 85.71%, 93.75%, respectively. The resistance degree to malathion was assessed as level "M". The knock down rates of Anopheles sinensis captured in day 1, day 7, day 15 and the F1 from Yixing 60 min after the exposure to 0.05% deltamethrin were 54.76%, 76.19%, 92.86%, and 52.38%, respectively, and the mortality rates post-24 h were 54.76%, 76.19%, 95.23% and 61.90%, respectively. The difference of mortality post-24 h between the mosquitoes of 1 day post-captured and F1 was not statistically significant (P > 0.05). The knock down rates 60 min after the exposure to 0.05% deltamethrin to the female and male F1 of Anopheles sinensis from Sihong were 28.57% and 40.48%, and the mortality rates post-24 h were 35.71%, 42.86% respectively, and the difference was not statistically significant (P > 0.05).
Conclusions: Anopheles sinensis in the field of Jiangsu Province has developed severe resistance to deltamethrin and DDT, initial resistance to malathion. In order to prevent the development of resistance to the insecticides, the integrated management measures should be adopted in the future.