Understanding interactions between biopesticides and partial crop resistance for management of aphid pests of brassica crops

蚜虫是农作物的重要害虫，需要新的、环境可持续的方法来控制它们。特别是，基于抗药性作物品种、生物杀虫剂和天敌等生物防治方法的新的综合虫害管理系统是有可能的。本研究的目的是为油菜上寄主植物的部分抗性与真菌生物农药之间的相互作用提供新的认识，为油菜上的重要害虫油菜小菜蛾的防治提供新的思路。我们的IPM策略是利用部分品种抗性来减缓蚜虫的发育，同时提高生防剂的性能。较慢的蚜虫发育增加了它们易受昆虫病原感染的时间(例如，通过防止幼龄幼虫通过蜕皮从真菌孢子‘逃脱’)。一个额外的好处是，部分抗性承受的选择压力将比主基因抗性低得多，应该会被证明更持久。通过科学文献和对JA信号通路和Camalexin生产的甘蓝型油菜多样性集的RNAseq分析，确定了部分抗性的候选甘蓝种质，将在侵染研究中使用甘蓝型油菜无性系筛选，以确定蚜虫的存活率和发育速度。JA/Camalexin的验证将使用RT-PCR进行。将使用实验室生物测定来量化选定的昆虫病原真菌(白僵菌、绿僵菌、Lecanicilliu、Isaria)对取食大白菜和甘蓝商业品种的甘蓝不同生活期的存活和寿命的影响(作为基线)。然后，将对一组真菌菌株进行生物测试，以确定它们对以表现出部分抗蚜性的油菜材料为食的油菜种群的毒力。将与敏感植物材料进行比较。

Aphids are important pests of crops and there is a need for new, environmentally sustainable methods for their control. In particular, there is potential for new integrated pest management systems based around biological control methods including resistant crop varieties, biopesticides and natural enemies. The aim of this project is to provide new knowledge on the interaction between partial host plant resistance in brassicas and fungal biopesticides for the control of cabbage aphid Brevicoryne brassicae, an important pest of brassica crops. Our IPM strategy is to use partial varietal resistance to slow down aphid developmental while at the same time enhancing the performance of biocontrol agents. Slower aphid development increases the time for which they are susceptible to entomopathogen infection (e.g. by preventing young instars 'escaping' from fungal spores by moulting). An added benefit is that partial resistance will be under a much lower selection pressure than major gene resistance and should prove more durable. Candidate Brassica accessions for partial resistance, identified through the scientific literature and by RNASeq analysis of a brassica diversity set for JA signalling pathway and camalexin production, will be screened in an infestation study using a B. brassica clone to determine aphid survival and rate of development. Validation for JA / camalexin will be done using rt-PCR. Laboratory bioassays will be used to quantify the effects of selected strains of entomopathogenic fungi (Beauveria, Metarhizium, Lecanicilliu, Isaria) on the survival and longevity of different life stages of B. brassicae feeding on Chinese cabbage B. rapa and a commercial variety of Brussels sprouts B. olereacea (as a baseline). Bioassays will then be done with a subset of fungal strains to determine their virulence to B. brassicae populations feeding on Brassica accessions that show partial aphid resistance. Comparisons will be made with susceptible plant accessions.