烟粉虱寄生蜂浅黄恩蚜小蜂和海氏桨角蚜小蜂表型可塑性的热响应机制

Bemisia tabaci biotype Q are the most serious invasive pests in China. The management of this superbug mainly relies on biological control because of its extremely quick development of resistance to insecticides and strong tolerence to high temperature. In this proposed project, we will target on two introduced parasitoids, Eretmocerus hayati and Encarsia sophia. To better understand the thermal phenotypic plasticity of these two parasitoids and the consequences on ecological fitnees under high-temperature stress, three experiments will be conducted. First, the thermal phenotypic plasticity related to body size, metabolic rates, fecundity and longevity which linked to life-history fitness, as well as maintenance and reproduction trade-off will be measured. Subsequently, the "host recognizable interval" and the "window of vulnerability" in the context of interference mechanism of the two parasitoids, as well as the ecological consequences on interspecific replacement or coexistence will be investigated under high thermal condition. Finally, we will study the synchronism of thermal responses between whitefly and parasitoids,the control effect of two parasitoids combined release, and establish models to simulate the whitefly-parasitoids population dynamics responding to thermal variations. The completion of this present project will contribute to a better understanding of the responding mechanism of thermal adaptation of parasitoids. Besides, it will be beneficial to the mass-rearing technology for high temperature tolerance parasitoid population, and the establishment of a modified releasing strategy. Our results will provide some new insights into overcoming the challenge of sustainable management of Bemisia tabaci.

针对重大入侵害虫Q型烟粉虱高温环境下缺乏有效天敌控制的实际需求，围绕昆虫热表型可塑性决定其生态适合度这一科学问题，采用发育生物学、昆虫生理学、行为及种群生态学的技术与方法，以其优势寄生蜂浅黄恩蚜小蜂和海氏桨角蚜小蜂为对象，重点研究：（1）两种寄生蜂热表型可塑性与适应性，揭示高温下寄生蜂生殖与生存的能量分配和资源权衡；（2）高温对两种寄生蜂种间干涉的"识别时间间隔"和"易感时间窗口"的调控，以明确种间干涉机制和种间互作效应对温度的响应机制；（3）高温下两种寄生蜂与烟粉虱发育的同步性，室内及田间模拟高温条件下两种蜂竞争替代或共存的生态过程，以及寄生蜂组合的协同控害效应，构建烟粉虱-寄生蜂种群动态对温度响应的数学模型。预期研究结果将从个体、种群及种间层面阐明烟粉优势寄生蜂的热适应性与响应机制，丰富昆虫热表型可塑性理论，为利用优势寄生蜂持续治理Q型烟粉虱提供理论依据与技术支持。

本项目针对烟粉虱在高温条件下种群暴发不易治理、抗药性不断增强的难题，以烟粉虱的两种优势天敌浅黄恩蚜小蜂和海氏桨角蚜小蜂为对象，围绕昆虫的热表型可塑性决定其在高温下的生态适合度这一科学问题，重点研究了：两种寄生蜂的热表型可塑性与适应性、种间竞争干涉的热响应机制，二者与寄主发育的同步性及协同控害的热响应机制。主要结果包括：1） 明确了两种寄生蜂均为卵育型寄生蜂；其个体发育均符合“温度-体型定律”；探明升高寄生蜂的发育温度、降低产卵温度，可最大程度提高发育速率，降低能量和生殖损耗，进而在缩短寄生蜂发育周期的前提下，提高了寄生蜂的生殖和生防潜力，并进一步明确了两种寄生蜂在高温环境中的防控效力。该结果为适当提高饲养温度（30℃）在室内高效扩繁寄生蜂提供了理论依据，同时揭示了温室及田间大规模释放寄生蜂的适宜环境温度（最适26℃）。2）明确了海氏桨角蚜小蜂被浅黄恩蚜小蜂复寄生的“易感时间窗口”远远宽于浅黄恩蚜小蜂自复寄生的“易感时间窗口”，在26、30和34℃下分别为13、10、8天和10.15、7.26和7.16小时，且均随温度升高而缩短；但由于浅黄恩蚜小蜂自复寄生的“易感时间窗口”出现在晚上，与雌蜂羽化高峰期（上午）相错，因此，高温条件下，浅黄恩蚜小蜂通过复寄生干涉海氏桨角蚜小蜂的作用更强。3）通过在棉田中布置开顶式笼罩，明确了温度升高不利于海氏桨角蚜小蜂防控烟粉虱；通过室内模拟田间高温进一步明确高温使海氏桨角蚜小蜂的发育减慢、繁殖力下降，与烟粉虱的同步性下降。将海氏桨角蚜小蜂和浅黄恩蚜小蜂按一定比例混合释放可以提高寄生蜂对烟粉虱的防控效率，即26℃适温下以3:1的比例释放，随田间温度升高，逐渐加大浅黄恩蚜小蜂所占比例至1:3。上述研究揭示了浅黄恩蚜小蜂和海氏桨角蚜小蜂的热可塑性及其适应性以及寄生蜂间竞争互作的热响应机制，可用于指导适应于高温环境的烟粉虱优势寄生蜂的规模化饲养和释放策略的制定，为用其有效、合理防治烟粉虱提供理论依据。