Research On Anopheles Sinensis Resistance To Commonly Used Insecticides

To achieve the goal of malaria elimination in 2020, it is important to manage sustainably malaria mosquitoes. So far, there’ve been many reports about Anopheles sinensis resistance to commonly used insecticides. We should give priority to get informed of the resistance levels, distributions and its dynamic trends of An.sinensis. For the ICDC lab strain of An.sinensis, we bioassayed the susceptibility of larvae and adults to insecticides, determined the enzyme activity of non-specific esterase (NSE), mixed function oxidase (MFO), glutathione-S-transferase (GST), and the frequency of kdr by AS-PCR, thus we realized the susceptibility background of the the ICDC lab strain, and were able to provide procedures for resistance determination by enzyme activities.On this basis, we determined the susceptibility of Puer population and Chengdu population where malaria had been epidemic, with the same method, and analyzed the potential mechanism and provided scientific evidence for local chemical control. During the long insecticides resistance surveillance operation of An.sinensis in our nation, a huge volume of data has been accumulated. However, such data are scattered, lack of systemic management and analysis. In this study, we collected data from 1960 to 2013 and established primarily the Insecticides Resistance Surveillance System of An.sinensis to mine the data and serve better for resistance management. The results are concluded as following:1. The ICDC lab strain of An.sinensis adults were susceptible to deltamethrin, beta-cypermethrin, and permethrin, while resistant to DDT. Compared with the previous data, the larvae were susceptible to deltamethrin, with LC50 being 0.0025 mg/L, less susceptible to beta-cypermethrin,with LC50 being 0.0047 mg/L and four times of that of the lab strain from Academy of military medical sciences. The susceptibility of An. sinensis larvae to temephos, spinosad, and dinotefuran as expressed by LCso(95%CI) was 0.1125(0.0921-0.1407),0.0047 (0.0035-0.0062), and 0.1744(0.1653-0.1840) mg/L, respectively, without available comparison. The enzyme activity of NSE in adults and larvae were 30.75 and 125.15 nmol α-NA/(min·mg pr), respectively, lower than that in Puer population and Chengdu population. The frequency of the kdr mutation gene (TTG to TTT or TGT) of the lab strain was 28.84%.2. An.sinensis Puer population and Chengdu population were resistant to deltamethrin, beta-cypermethrin, permethrin, and DDT. Among the three strains/populations, Puer population adults and larvae were the highest in NSE enzyme activity, the lowest in MFO enzyme activity. The frequency of the kdr mutation gene of Puer population was 36.67%. So the resistance mechanism of An.sinensis Puer population mainly lied in the high activity of NSE and GST, and knock down resistance. The elevated activity of three metabolic enzymes attributed to An.sinensis Chengdu population resistance.3. Through the analysis of the Insecticides Resistance Surveillance System of An.sinensis, we found surveillance on An.sinensis resistance to deltamethrin distributed in 66 sites of 9 provinces,52 of which (78.79%) presented resistance; to DDT in 66 sites of 15 provinces,54 of which (81.82%) resistance; to malathion in 29 sites of 6 provinces,15 of which (51.72%) resistance; to propoxur in 12 sites of 3 provinces,3 of which (25%) resistance. An.sinensis which had presented resistance to deltamethrin developed cross resistance to beta-cypermethrin, permethrin, DDT and malathion.