巴氏新小绥螨及其猎物对高温波动的非同步性响应机制

The frequent occurrence of high temperature fluctuation is vital to population dynamics of Phytoseiidae predators and Tetranychidae preys and often directly causes biological control disruption. Most pest mites are highly adapted to high temperatures and their abundance is promoted under hot and dry field conditions, whereas that of Phytoseiid predators is demoted, which make an unprecedented challenge to biological control effectiveness of pest mites with Phytoseiid predators. In this proposed project, we target on three species of Tetranychidae, i. e. Panonychus citri, Eotetranychus kankitus and Tetranychus urticae, and a Phytoseiidae predator of Neoseiulus barkeri with two strains, i.e. conventional strain (CS) and high temperature adapted strain (HTAS). To better understand the non-synchronization response mechanism between predators and preys caused by the thermal phenotypic plasticity under high temperature fluctuations and the consequence on ecological fitness, four experiments will be conducted. Firstly, the thermal phenotypic plasticity related to growth and development, body size, metabolic rates, fecundity and longevity which are linked to life history fitness, behavioral response, as well as maintenance and reproduction trade-off will be measured. Secondly, the high temperature susceptibility, survival and reproduction under single and repeated heat stress conditions will be studied. Thirdly, the HSPs expression pattern will be analyzed using PT-PCR and Western blot; the benefits and costs of Hsp70 expression will be studied taken survival and reproduction into consideration. Finally, potted experiment will be carried out to evaluate the biological efficiency under high temperature. The completion of this present project will contribute to a better understanding of the responding mechanism of thermal adaptation and the consequently non-synchronization between predatory mite and spider mites. The results will provide some new insights into overcoming the challenge of sustainable management of spider mites.

频繁发生的温度波动影响天敌对害虫害螨种群控制的稳定性，高温下植绥螨与害螨种群活力两极化的热可塑性差异机制已成为影响其高效利用的关键科技问题。本项目以巴氏新小绥螨为对象，在已筛选获得高温品系和利用生命表技术分析发现高温下巴氏新小绥螨与猎物存在非同步性加剧现象的基础上，重点开展①从生存策略及种群动态等解析巴氏新小绥螨与猎物对高温波动的生物生态学响应机制，②高温环境所引起的巴氏新小绥螨与其靶标猎物的生理适应性差异，③利用RT-PCR和Western-blot技术，从mRNA、蛋白水平解析巴氏新小绥螨与猎物热激蛋白HSPs在温度胁迫下的表达模式及与生殖存活之间的关联，④模拟试验比较分析常温、高温品系控害效率等。研究结果将从个体、种群和种间层面阐明巴氏新小绥螨与害螨对高温波动的非同步性机制，丰富和完善营养级敏感性假说与热表型可塑性理论，并为全球气候变化下高效利用捕食螨控制害螨爆发提供理论基础。

植绥螨与农业害螨热表型可塑性存在差异，常表现为高温环境下害螨易爆发成灾、植绥螨防控效率差。针对这一科技问题，本项目筛选获得巴氏新小绥螨耐高温品系，以两种品系的巴氏新小绥螨为主要研究对象，重点从巴氏新小绥螨及其猎物生长发育同步性、生殖与存活策略差异、两种品系热激蛋白表达模式、控害能力及生理生化响应差异等方面深入研究。结果发现，巴氏新小绥螨两种品系均能在中等高温环境中完成生长发育，但适合度降低，柑橘害螨经历短时高温胁迫后发育历期延长，但对其存活及后代的影响不显著。巴氏新小绥螨两种品系对高温敏感性差异显著，卵对高温敏感性低于叶螨，雌成螨对高温敏感性高于叶螨，在中等高温环境和经历短时高温胁迫后，生殖力降低。巴氏新小绥螨雌、雄成螨分别或同时遭遇高温胁迫后，雌成螨生殖力显著下降，但子代卵孵化率未受到影响。而柑橘害螨经历短时高温胁迫后生殖力降低，但短时高温胁迫的时间（2h、4h）对其无显著影响。以四种不同猎物为食，巴氏新小绥螨在取食二斑叶螨时种群的净生殖率和周限增长率最高，巴氏新小绥螨经历高温胁迫后对二斑叶螨若螨的功能反应为Holling II型，常温品系取食量呈下降趋势，而耐高温品系无明显变化。筛选获得5个巴氏新小绥螨HSP基因，其相对表达量在两种品系不同发育阶段中均存在显著性差异，且在经历短时高温胁迫后均上调表达，其中Hsp70和Hsp40显著上调表达，HSP70-1蛋白含量显著增加。高温胁迫能显著增强两种品系雌成螨的SOD、CAT、POD以及GSTs活性，但清除ROS能力有限，发现巴氏新小绥螨抗氧化酶系统可能参与其高温驯化过程。研究结果从个体、种群和种间层面阐明巴氏新小绥螨与害螨对高温波动的非同步性响应，为全球气候变化下高效利用捕食螨控制害螨爆发提供理论基础。