天敌胁迫诱导蜜露微生物调控红火蚁保护粉蚧的机制研究

Mutualism is a typical and important interaction among species in ecosystems. This mutualistic relationship plays a very important role in the process of alien ant invasion. Previous studies have shown that natural enemy threat and sterilization treatment of honeydew can affect the tending behavior of fire ants, but the mechanism is still a lack of understanding. The project focuses on the behavioral and chemical mechanism of regulation effect of microorganisms from honeydew induced by predator stress on defending mealybugs by fire ants, the main research contents are as follows: 1) To determine the effects of the predator stress on microorganisms of P. solenopsis honeydew and identified microbial strains can be cultivated; 2) Systematic analysis of the effect of volatile produced by bacteria on tending behavior of fire ants and reveal the chemical mechanism; 3) The test of effect of microorganisms of P. solenopsis honeydew on the tending behavior and natural enemy preying by fire ants, further explain the regulation of symbiotic bacteria under the stress of natural enemy; 4) Reveal the changes in expression of key bacteria genes related to synthesis compounds under the stress of natural enemies and distribution of bacteria in the gut. Base on perspective of the environmental stress induced defiance, this project mainly explore the mechanism of regulation of bacterial symbiont on mutualism between the fire ants and mealybugs, and may reveal a new regulation mechanism of bacterial symbiont on interspecific relationship.

互惠关系是物种间相互促进的重要生态学现象，它在外来蚂蚁入侵过程中发挥着重要作用。前期研究表明天敌胁迫和蜜露灭菌处理可影响红火蚁对粉蚧的照看行为，但其中的机制仍缺少认识。本项目拟就天敌胁迫诱导扶桑绵粉蚧蜜露微生物调控红火蚁保护粉蚧的行为和化学机制进行重点研究，主要研究内容有：1）测定天敌胁迫对扶桑绵粉蚧蜜露的微生物的影响并鉴定出可培养的菌种；2）借助GC-MS对天敌胁迫后的蜜露气味进行化学成分鉴定；3）测定天敌胁迫对红火蚁照看行为和捕杀天敌的影响，阐明天敌胁迫下蜜露微生物的行为调控作用；4）揭示天敌胁迫下细菌中合成相关活性化合物关键基因的表达规律及关键菌在粉蚧肠道中的变化。本项目从环境压力诱导防御反应的角度研究微生物调控红火蚁与扶桑绵粉蚧的互惠机制，研究结果将有助于揭示微生物调控物种间关系的新机制。

互惠关系是物种间相互促进的重要生态学现象，它在外来蚂蚁入侵过程中发挥着重要作用。前期研究表明天敌胁迫和蜜露灭菌处理可影响红火蚁对粉蚧的照看行为，但其中的机制仍缺少认识。本项目就天敌胁迫诱导扶桑绵粉蚧蜜露微生物调控红火蚁保护粉蚧的行为和化学机制进行重点研究，取得如下重要结果：1）明确天敌胁迫条件下扶桑绵粉蚧肠道及蜜露共生微生物变化。通过差异性分析发现消耗性胁迫48h后鞘氨醇单胞菌属Sphingomonas在肠道中的相对丰度显著增加，葡萄球菌属Staphylococcus在肠道中的相对丰度显著下降。2） 扶桑绵粉蚧和蜜露中可培养细菌的分离纯化及鉴定。从蜜露中分离得到分别属于类芽孢杆菌属Paenibacillus和细杆菌属Microbacterium的细菌，从粉蚧虫体中分离得到分别属于节杆菌属Arthrobacter、香味菌属Myroides、葡萄球菌属Staphylococcus、单胞菌属Brevudimonas、新鞘氨醇杆菌属Novosphingobium、短杆菌属Brevibacillus、肠球菌属Enterococcus、醋杆菌属Acetobacter、微球菌属Micrococcus、类芽孢杆菌属Paenibacillus、短小杆菌属Curtobacterium、细杆菌属Microbacterium、短状杆菌属Brachybacterium、芽孢杆菌属Bacillusd的14种细菌。3）扶桑绵粉蚧蜜露挥发性成分分析。利用气相色谱与质谱联用技术（GC-MS），鉴定了扶桑绵粉蚧蜜露中的挥发性成分，从蜜露中鉴定出多种酮类、醛类，烯烃等具挥发性的有机化合物。本项目从环境压力诱导防御反应的角度研究微生物调控红火蚁与扶桑绵粉蚧的互惠机制，研究结果将有助于揭示微生物调控物种间关系的新机制。