杀虫剂对Q烟粉虱传播TYLCV的影响及其行为机制

Virus transmission is substantially affected by the behaviors of vector insect. The combined behavioral manipulation by abiotic and biotic factors is the base to illuminate the emergence and epidemiology mechanisms of plant viral disease. In recent years, Tomato yellow leaf curl virus (TYLCV) and it’s whitefly vector, Bemisia tabaci (Gennadius), outbreak persistently in China. Insecticide was widely applied to control B. tabaci, while the damage of TYLCV becomes increasingly serious. Our previous study indicated that the B. tabaci behaviors were manipulated by a separately factor, e.g. thiamethoxam or TYLCV, however, the combined manipulation by insecticide and TYLCV is less explored. Given the fact that the TYLCV still spread efficiently under the insecticide pressure in the field, we therefore speculated that the B. tabaci behaviors may be combined manipulated by insecticide and TYLCV. In the present study, we simulate the field condition and aim to explore the effects of three kinds of insecticides under the sublethal dose exposure on the TYLCV acquisition and transmission capacity of B. tabaci Q. We subsequently determine the combined manipulation effects of the insecticides and TYLCV on host selection and feeding behavior of B. tabaci Q. The results will help to illuminate the behavioral character and the underlying mechanisms of TYLCV transmission by B. tabaci Q under the pressure of insecticide. Furthermore, the results would be benefit to expand the theory of the plant-mediated whitefly-begomovirus interactions, and to further provide a theoretical foundation for the efficient management of begomovirus in the field.

媒介昆虫行为是影响植物病毒传播的重要因素。明确非生物和生物因子对昆虫行为的联合修饰作用，是阐明植物病毒病发生流行机制的基础。近年来，烟粉虱及其传播的番茄黄化曲叶病毒（TYLCV）病在我国持续暴发危害，生产中通常施用杀虫剂控制媒介昆虫烟粉虱，但TYLCV病毒病危害反而越来越严重。我们前期研究发现，单一因子噻虫嗪或TYLCV均可修饰烟粉虱的行为。我们推测：杀虫剂和TYLCV对烟粉虱行为存在联合修饰作用，导致施药条件下病毒仍可在田间高效扩散传播。本研究模拟田间用药，研究三种常用新型杀虫剂在亚致死剂量下对Q烟粉虱获取和传播TYLCV效能的影响，并进一步研究杀虫剂与TYLCV对Q烟粉虱寄主植物选择行为和取食行为的联合修饰作用。研究结果将有助于从行为学角度探明杀虫剂作用下Q烟粉虱传播TYLCV的特性和机制，丰富烟粉虱、寄主植物和双生病毒间的互作理论，为田间双生病毒病的有效防控提供理论依据。

本项目明确了杀虫剂和茉莉酸途径对烟粉虱传播番茄黄化曲叶病毒（TYLCV）的影响及行为机制。首先研究了三种杀虫剂对无毒和带毒烟粉虱的亚致死效应，噻虫嗪、溴氰虫酰胺和呋吡呋喃酮对无毒Q烟粉虱的亚致死浓度（LC15）分别为10.76mg/kg、1.52mg/kg和5.78mg/kg，对带毒Q烟粉虱的亚致死浓度（LC15）分别为37.02mg/kg，1.75mg/kg，和11.75mg/kg。噻虫嗪和呋吡呋喃酮对带毒烟粉虱的亚致死浓度显著高于无毒烟粉虱。在溴氰虫酰胺和噻虫嗪亚致死处理下，带毒Q烟粉虱的适应性指标显著显著优于无毒Q烟粉虱。表明携带TYLCV降低了烟粉虱对杀虫剂的敏感性，而提高了烟粉虱适应性。噻虫嗪处理对带毒和无毒Q烟粉虱取食行为均产不利影响，同时显著降低TYLCV修饰Q烟粉虱韧皮部取食行为的能力。与对噻虫嗪敏感种群相比，抗噻虫嗪B烟粉虱取食行为没有显著变化。还研究了5种杀虫剂对番茄黄化曲叶病毒病（TYLCD）的防治效果，结果表明呋吡呋喃酮120g/hm2和180g/hm2对TYLCD防治效果分别达到83.0%和97.9%，与溴氰虫酰胺效果（88.17%）相当，显著优于稳特（63.92%）、螺虫乙酯（9.61%）、吡虫啉（46.41%），表明呋吡呋喃酮和溴氰虫酰胺均是防治TYLCD较为理想的药剂。带毒和无毒B烟粉虱在不同茉莉酸（JA）表达基因型番茄上取食结果表明：在非韧皮部刺探阶段，无论是在JA缺失（spr2）、野生（WT）还是过表达基因型（35S）番茄上，携带TYLCV较无毒B烟粉虱刺探更好。在韧皮部取食阶段，带毒较无毒B烟粉虱在JA缺失和野生型番茄上取食依然较好，而在JA过表达番茄上，病毒侵染没有显著影响B烟粉虱的取食。可见植物高JA水平抑制了TYLCV修饰B烟粉虱取食行为的能力。进一步利用荧光定量PCR研究B烟粉虱的传毒效率，暴露于带毒B烟粉虱10天后，35S植物中的病毒量比spr2植物低74%，而注射携带TYLCV的农杆菌侵染性克隆10天以后，spr2和35S植物中的病毒滴度没有显著差异。表明在寄主植物介导的病毒和媒介昆虫互作中，降低病毒对媒介昆虫取食行为的修饰能力可能是植物防御反应抑制病毒传播的广泛机制。