昆虫的社会性免疫是由群体产生的对发生免疫反应的个体和其他个体都有益的免疫机制。 它在社会性昆虫抵御病原物侵染及生物防治中扮演重要角色。前期研究显示柠檬醛在不接触虫生真菌孢子的情况下可抑制其萌发，表明柠檬醛可能参与了红火蚁的社会性免疫，但其产生、释放、作用机制等均不清楚。本项目测定柠檬醛对红火蚁蚁巢内常见病原微生物的熏蒸抑菌活性，阐明其生物效应；运用GC-MS等化学分析技术测定揭示红火蚁不同品级、身体不同部分和主要腺体中柠檬醛的含量，明确柠檬醛的来源；进一步解析不同体型和年龄的工蚁、不同发展阶段蚁群和病原真菌胁迫下蚁群的柠檬醛产生释放规律。本项目将阐明柠檬醛在红火蚁群体中的生物效应及产生释放规律，更全面认识蚂蚁与病原物互作机理，为通过调控社会免疫提高虫生真菌对红火蚁的防效提供理论依据。

Social immunity in the context of eusocial insects is the set of immune mechanisms mounted in a colony to protect overall homeostasis for the benefit of all nestmates. It is a main barrier against pathogens and invaders. Our prior results demonstrate citral, a volatile produced by red imported fire ant Solenopsis invicta, can inhibit spore germination of Metarhizium flavoviride by fumigation. However, nothing to date is known about function of citral in social immunity of S. invicta and its source and release. Firstly, we test the fumigation of citral against common pathogens in S. invicta mounds, i.e. Metarhizium flavoviride, Beauveria bassiana, Purpureocillium lilacinum, Bacillus thuringiensis, and Serratia marcescens. Then, we use gas chromatography coupled with mass spectrometry (GC-MS) to identify source of citral by checking the individuals of different castes of S. invicta, as their isolated body parts and main glands. Further, we test whether the amount of citral was varied among worker size and age, different growth stages of colony base on GC-MS. Moreover, it is possible that associated entomopathogenic fungi can trigger the production and release of citral, which can be tested by infecting colonies in the lab. The present project aims to identify function of citral in S. invicta and clarify the source of citral and secretion patterns among nestmates of different castes. The knowledge generated in this study can be used to build a solid foundation for further study on mechanisms of social immunity in ants and facilitate the development of new strategies for managing S. invicta.