三带喙库蚊抗性水平与其对乙脑病毒易感性关系的研究

RELATIONSHIP BETWEEN INSECTICIDE RESISTENCE AND SUSCEPTIBILITY OF CULEX TRITAENIORHYNCHUS INFECTED ORALLY BY JAPANESE ENCEPHALITIS VIRUS

为了解三带喙库蚊Culex tritaeniorhynchus抗药性水平与其对乙脑病毒易感性之间的关系，本研究采用浸渍法对野外采集的不同种群三带喙库蚊幼虫抗药性水平进行测定，同时对同批次蚊虫经口感染乙脑病毒，RT．PCR法检测感染率。生测结果显示三带喙库蚊幼虫实验室品系（LAB）、南京江浦种群（NJJP）、濉溪南坪种群（SXNP）、安康建民种群（AKJM）F1代和安康建民种群（AKJM）F3代对溴氰菊酯的半数致死浓度（LC50值）分别为0．0009、0．0071、0．0160、0．0027和0．0025mg／L，与敏感品系相比，抗药性指数在2．30～40．05之间；对高效氯氰菊酯的半数致死浓度（LC50值）分别为0．0043、0．0117、0．0528、0．0121和0．0141mg／L，抗药性指数在2．13～26．42之间。感染实验结果显示，三带喙库蚊实验室品系、南京江浦种群、濉溪南坪种群、安康建民种群F1代和安康建民种群F3代对乙脑病毒的感染率分别为84．44％、80．56％、62．5％、86．00％和91．89％。相关性分析结果显示：三带喙库蚊对乙脑病毒的感染率与其对溴氰菊酯和高效氯氰菊酯的抗性指数之间均有线性负相关关系（腰值分别为0．887和0．783，P值分别为0．0167和0．0460）。表明三带喙库蚊在杀虫剂的选择压力下，可能会影响其对乙脑病毒易感性，但这种影响的机制尚待进一步研究。

Five strains of Culex tritaeniorhynchus were evaluated for their susceptibility to deltamethrin and betacypermethrin. Larval bioassays were carried out in accordance with WHO mosquito susceptibility tests. The results showed that the LC50 values of Cx. tritaeniorhynchus against deltamethrin in LAB, NJJP, SXNP, AKJM （F1） and AKJM （F3） strain were 0. 0009, 0. 0071,0. 0160, 0. 0027 and 0. 0025 mg/L respectively. Compared to the susceptible strains reported in previous literature, the resistance ratio of these strains varied from 2. 30 to 40. 05. The LC50 values of Cx. tritaeniorhynchus against beta-cypermethrin in LAB, NJJP, SXNP, AKJM （F1） and AKJM （F3） strain were 0. 0043, 0. 0117, 0. 0528, 0. 0121 and 0. 0141 mg/L respectively. Compared to the susceptible strains reported in previous literature, the resistance ratio of these strains varied from 2. 13 to 26. 42. Five strains of Cx. tritaeniorhynchus were orally infected by Japanese encephalitis virus. Infection rate of Cx. tritaeniorhynchus in LAB, NJJP, SXNP, AKJM （F1） and AKJM （F3） strain was 84. 44% , 80. 56% , 62.5% , 86. 00% and 91.89% respectively. Regression analysis showed a significant correlation between the infection rate of different strains and the LC50 values of mosquito against dehamethrin and beta-cypermethrin. Susceptibility of Cx. tritaeniorhynchus infected by Japanese encephalitis virus may be affected by the insecticide resistance. Further studies are needed to determine the specific mechanism.