除虫菊是菊科观赏植物，以含天然杀虫剂除虫菊酯著称。前人研究主要集中于非挥发性的除虫菊酯，是否存在挥发物途径的抗虫尚无报道。我们前期调研到除虫菊与作物套种模式，发现可减少农作物害虫；田间除虫菊花期没有蚜虫但有大量瓢虫且检测到高丰度的挥发物法尼烯（EβF）。推测除虫菊存在基于EβF为主的挥发物引诱天敌防御害虫的新途径。本项目通过自然和胁迫下除虫菊不同发育阶段和组织的挥发物检测并结合昆虫行为实验，了解除虫菊基于EβF信号的植物-害虫-天敌关系；克隆除虫菊EβF合成酶基因，通过蛋白体外表达及除虫菊和菊花中沉默和超表达后挥发物检测和昆虫行为实验，明确其基因功能；对携带ProEβFS::GUS的除虫菊进行启动子活性分析并结合EβFS亚细胞定位明确EβF合成部位和响应特性。该研究对揭示除虫菊基于挥发物的新型抗虫机制有重要学术意义，且对开发利用植物自身防御能力，减少化学农药的施用等具有重要的产业环保意义。

Pyrethrum, an ornamental plant in Asteraceae, is famous for its natural pesticide pyrethrin. Previous research was mostly focused on the roles of the non-volatile pyrethrins to protect this plant against insect pests. However, the plant possesses another insect resistance pathway based on terpene volatiles which has not been reported until now. We have observed different intercropping ways between pyrethrum and fruit trees,vegetables and crops ,and pests on crops were reduced.Also in pyrethrum field ladybirds are attracted in large numbers to pyrethrum flower buds, despite the fact that hardly any aphids or other prey insects are present. Their presence however correlated with a very high content of E-β-Farnesene peaking in stage 2 flower (not fully opened buds). We hypothesized that pyrethrum has evolved a natural mechanism to enhance its reproductive success by recruiting ladybirds and dispersing aphids by E-β-Farnesene-based volatiles. Firstly, experiments to collect and detect headspace components from different pyrethrum organs during different developmental stages under both natural and stress conditions will be developed to analyse the emission of EβF. Moreover, insect behavior assays are combined to reveal the relationship among plant-aphid-ladybird beetle based on signal recognition of EβF in pyrethrum. Secondly, functional characterization of EβF Synthase is used to confirm the function of EβFS in vitro, combined with genetic engineering by silencing of EβFS in pyrethrum and overexpression of EβFS in chrysanthemum under control of the EβFS promoter. Thirdly, analysis of EβFS promoter activity is achieved in transgenic pyrethrum carrying ProEβFS::GUS constructs allowing the analysis of the subcellular localization of EβFS. It will help to determine precisely site of synthesis of EβF and the transcript regulation mechanism of EβFS. This work not only reveals a new insect resistance pathway based on volatiles in pyrethrum, but is also expected to reduce the usage of chemical pesticides by introducing such similar strategies into crop plants.