共生菌与宿主互作机制是生态学及进化生物学研究的重要前沿领域。前期研究发现，我国重大农业入侵害虫Q烟粉虱内共生菌Cardinium（简称C菌）是导致该害虫适合度代价的根源。围绕“共生菌介导宿主适合度代价的机制”这一科学问题，本项目拟采用生理学、行为学及分子生物学方法，以相同遗传背景的Q烟粉虱C菌感染(C+)与未感染种群(C-)为对象，重点研究：1）比较C+与C-生殖发育、营养代谢及取食行为差异，从生理学与行为学角度明确C菌介导烟粉虱适合度代价的直接影响机制；2）比较植物与C+/C-互作中植物防御响应与烟粉虱解毒代谢的差异，从植物-昆虫互作角度揭示C菌介导烟粉虱适合度代价的间接影响机制。研究成果对深化Cardinium与昆虫互作机制的认识，揭示Q烟粉虱灾变机制以及拓展害虫防控新途径具有重要理论意义和实践价值。

The mechanism underlying the endosymbiont-host interaction is one key scientific issue in the field of ecology and evolutionary biology. Our previous studies showed that the symbiont Cardinium is the origin of the fitness cost of Bemisia tabaci Q (also known as MED species), one most important agricultural pest in China. Using the Cardinium-infected (C+) and uninfected (C-) populations of Q with same genetic background, with the methods in physiology, behavior, and molecular biology, the research will focus on the main aspects to reveal the mechanism underlying the fitness cost of host: 1) The difference of reproductive development, nutrition metabolism, and feeding behavior in C+ and C- populations will be analyzed and compared, which will determine the direct effects of this symbiont on the fitness costs of Q at the physiological and behavioral levels; 2) the difference of the defense response of host plant to C+/C- and the detoxification mechanism in C+/C- will be compared, which reveal the indirect effects of this symbiont on the fitness costs of Q at the plant-insect interaction. These results will be significant to the understanding of the mechanism of the Cardinium-host insect interaction and of the ecological mechanism of invasion of Q, and to the control of pest adopting novel methods.