入侵害虫红棕象甲特异性免疫致敏和跨代传递效能及其调控机理

Red palm weevil, Rhynchophorus ferrugineus Oliver, is a key devastating pest that invaded the planting regions of the palm trees in the southern of China. However, the efficiency of biological control against red palm weevils is severely restricted due to the significant immune priming and its trans-generational transmission. In this project, the survival of host and measuring the parameters related to immunity after immune priming by different pathogens will be clarified using the physiological ecology and molecular biology technology, and the phenomenon of the specific immune priming and the physiological response mechanism in red palm weevil will be revealed. The main constituents of the priming factors will be further cleaned under the method of serum transfection. Meanwhile, the key genes regulating the process of immune priming will be identified by comparing transcriptome to reveal its regulation mechanism. The protective mechanism of the immune priming on the offspring will be revealed from the level of gene and protein expression, the dynamic association between trade-off of immune priming and reproductive adaptability will be investigated based on the analysis of the survival and mating reproduction of the host, and some possible mechanisms of transgenerational transmission were explored focused on three perspectives of DNA methylation, vitellogenin and symbiotic microorganisms. This research will uncover adaptive variation mechanism of invasive pests from the perspective of R. ferrugineus immune priming and trans-generational transmission, to enrich and improve the research system of invasive biology. Also, the study will not only attribute to further analysis about the immune interaction and diversified defense strategies between R. ferrugineus and pathogens to improve the natural control effect in the field, but also provide a new idea and approach for the development of new-type pest inhibitor which takes the insect immune system as a target.

红棕象甲是新近入侵我国的一种重大毁灭性害虫。然而由于该虫存在显著的免疫致敏及其跨代传递效应，严重制约了红棕象甲的生物防治效能。本项目采用生理生态学和分子生物学技术，分析不同病原菌免疫致敏后红棕象甲的生存和免疫响应，阐明其特异性免疫致敏效能及其生理响应机制；通过血清转染的手段揭示免疫致敏效应因子的组成，应用比较转录组分析调控免疫致敏的关键基因，揭示其调控机理；从基因和蛋白表达水平上揭示免疫致敏对子代的保护机制，结合寄主存活和交配繁殖特性，明确雌雄成虫免疫致敏与繁殖适应性间的动态权衡，并从DNA甲基化、卵黄原蛋白和共生菌等三个角度探讨免疫致敏跨代传递效应的机理等。该研究不仅从免疫致敏和跨代传递的视角，揭示红棕象甲适应性变异机制，丰富和完善入侵生物学研究体系，而且有助于深入剖析免疫互作效应和多样化的防御策略，提高病原菌田间控害效果，为开发以昆虫免疫系统为靶标的害虫新型抑制剂等提供新的思路和方法。

红棕象甲是新近入侵我国的一种重大毁灭性害虫。然而由于该虫存在明显的免疫致敏效应，严重制约了生物防治的效能。本研究明确了红棕象甲存在针对Bt等革兰氏阳性菌的特异性免疫致敏现象，可使生存率提升34.7%，且血细胞增殖以及吞噬能力增强，阐明其特异性免疫致敏效能及其生理响应机制；发现Bt致敏诱导NimB2、TEP3上调表达，促进血细胞的吞噬作用增强，提高免疫致敏效率，且Bt致敏能够诱导血细胞一些免疫相关基因和解毒代谢相关基因的表达，具有免疫记忆功能，一些神经肽（tachykinin-related peptide和adipokinetic hormone）也参与了免疫致敏的调控，且存在独特的病原诱导血细胞增殖机制，尤其是诱导五羟色胺合成是实现致敏免疫保护的一个重要机理；存在由雌虫传递的特异性跨代免疫致敏现象，病原菌可以从雌虫传递至发育中的胚胎，参与早期卵的免疫致敏，且致敏子代脂肪体中PGRP-LC和Attacin显著上调表达，使子代在受到致敏亲代的病原物二次侵害时产生更强的免疫反应；Bt致敏后，Toll通路SPZ基因高表达，蜕皮激素合成通路基因SHADOW和SHADE显著下调，引起蜕皮激素含量减少，延缓幼虫的发育，幼虫体重和体长增加受阻，降低了卵巢中JH含量、保幼激素合成基因JHAMT和卵巢中Vg的表达，从而使生殖力降低，阐明了成虫免疫致敏与繁殖适应性间的动态权衡；Bt致敏可以引起亲代和子代DNA甲基化水平上调和组蛋白乙酰化修饰水平下调，而这两种表观修饰的改变影响了子代的跨代致敏保护效应和免疫相关基因的表达，在免疫致敏的跨代传递中发挥重要的调控作用。该研究不仅从免疫致敏和跨代传递的视角，揭示了红棕象甲适应性变异机制，丰富和完善入侵生物学研究体系，而且有助于深入剖析免疫互作效应和多样化的防御策略，提高病原菌田间控害效果，为开发以昆虫免疫系统为靶标的害虫新型抑制剂等提供新的思路和方法。