班氏跳小蜂定位扶桑绵粉蚧的化学通讯机制

Phenacoccus solenopsis is an important invasive pest, and has caused serious damage on many plants. Aenasius arizonensis is a dominant natural enemy of this pest, discovering and locating host is the prerequisite for the multiplication and functioning of this parasitic wasp. Chemical volatiles of the healthy and parasitized mealybug, healthy and pest damaged host plants, honeydew will be collected by dynamic headspace adsorption method from the perspective of insect chemical ecology. The GC-MS and GC-EAD will be used to isolate, identify and screen the active components with electrophysiological and behavioral activity of parasitic wasp to clarify the signaling substances that play a dominant role in the host selection. RNA-seq, eukaryotic expression, isolation and purification will be used to obtain odorant binding proteins (OBPs). The binding properties of OBPs and active components will be detected by fluorescence binding assay. The physiological functions of OBPs will be determined by RNAi technique to clarify the ambiguities of OBPs in olfactory odorant smell and host location behavior. This project can clarify the physiological and molecular mechanisms of the host location of A. arizonensis, and provide the theoretical basis for the screening of parasitic wasp attractants, and also provide scientific basis for digging the biocontrol potential of A. arizonensis in enhancing the biocontrol effect on this pest.

扶桑绵粉蚧作为重要入侵害虫严重为害多种植物，班氏跳小蜂为其优势天敌，发现和定位寄主，是其种群繁衍并发挥作用的前提。本项目从昆虫化学生态学角度出发，以植物-蚧虫-天敌三级营养层信息交流为研究体系，采用动态顶空吸附法、GC-MS、GC-EAD、转录组测序、荧光竞争结合、RNAi等方法和技术，收集提取健康和虫害植物、健康和已寄生粉蚧及蜜露的挥发物，分离、鉴定、筛选对寄生蜂具有电生理及行为活性的组分，明确班氏跳小蜂寄主选择行为中起关键作用的信号物质；分离纯化得到班氏跳小蜂触角气味结合蛋白OBPs，检测OBPs与活性组分的结合特征；明确OBPs的生理功能，阐明OBPs在班氏跳小蜂嗅觉感受及寄主定位行为中的作用。预期研究结果有望阐明班氏跳小蜂寄主定位的生理和分子机制，为寄生蜂引诱剂的筛选提供理论基础，为挖掘班氏跳小蜂的生防潜力、强化其生防效果提供科学依据。

扶桑绵粉蚧是一种世界性入侵害虫，为我国重要入境检疫对象，广西为其高度适生区。班氏跳小蜂为扶桑绵粉蚧的优势天敌，田间可抑制粉蚧种群。项目研究了班氏跳小蜂对朱槿、马铃薯、棉花、番茄饲养的扶桑绵粉蚧的趋性，调查了广西扶桑绵粉蚧寄生蜂种类、寄生率及动态，分离鉴定了扶桑绵粉蚧及其寄主挥发物的组成，测定了班氏跳小蜂对15种化合物的触角电位反应和对5种化合物的嗅觉行为反应，提取了班氏跳小蜂触角总RNA，并进行了OBPs功能注释。结果表明，班氏跳小蜂对朱槿、马铃薯和棉花饲养的扶桑绵粉蚧成虫的趋性和寄生率显著强于和高于番茄的。野外采集到9种寄生蜂，班氏跳小蜂是扶桑绵粉蚧的优势寄生蜂，南京刷盾跳小蜂是班氏跳小蜂的重寄生蜂；寄生蜂发生高峰期为5-9月，班氏跳小蜂野外最高寄生率约30%。扶桑绵粉蚧共检测到11种化合物，寄主植物共检测到62种化合物，其中棉花、番茄和朱槿分别有36种、39种和31种化合物。有3种化合物（十四烷、十七烷、2,6-二叔丁基对甲酚）在扶桑绵粉蚧和3种寄主植物不同状态下均被检测到。健康状态植株的烷烃类化合物含量较高，粉蚧取食后植株挥发物中烯萜类化合物的含量均增高。班氏跳小蜂对α-蒎烯、β-蒎烯、月桂烯均无EAG反应；在100 ug/ul下，班氏跳小蜂EAG响应值次序为苯甲醛＞苯乙酮＞正辛醛＞葵醛＞壬醛＞苯乙烯＞异辛醇＞乙酸丁酯＞蒎烯＞豆蔻醇＞月桂醇＞十七烷。5种化合物对班氏跳小蜂雌虫的引诱能力为：乙酸丁酯＞壬醛＞十七烷＞苯乙烯＞异辛醇。但触角电位反应和嗅觉行为反应存在差异，需进一步田间验证。班氏跳小蜂为扶桑绵粉蚧的优势寄生蜂，应用前景广阔。但南京刷盾跳小蜂严重削弱班氏跳小蜂的生防效果，应加以重视。本研究为挖掘扶桑绵粉蚧及其寄主植物的活性物质奠定了基础，为限制南京刷盾跳小蜂提高班氏跳小蜂的生防效果提供了新思路。