Intraspecific chemodiversity in Tanacetum vulgare shapes above- and belowground plant-associated communities

在第一个资助阶段，我们的目标是在植物群落水平上操纵Tanacetum vulgare的化学多样性，研究这些植物与蚜虫之间的相互作用。因此，我们建立了一个化学多样性的田间实验，共84个样地和504株，在样地水平上，Tanacetum vulgare萜类化学型丰富度（由P5和P6确定）在1 ~ 6之间。我们采集了昆虫群落（主要是蚜虫和捕食者）、植物生长参数以及顶空挥发性有机化合物（包括P1和P2）。田间昆虫和挥发性数据目前正在分析中，但初步分析表明，样地水平的化学型丰富度对蚜虫定殖有影响，特别是对镰刀孢霉丰度有积极影响。在实验室条件下，我们对所使用的化学型进行了两两选择分析，选择了两种专门针对T. vulgare的蚜虫，tanacetmacrosiphoniella tanacetia和Uroleucon tanaceti （P5）。我们发现化学型影响两个物种的选择行为，萜类多样性倾向于排斥，而总萜类浓度倾向于吸引。从自下而上和自上而下的盆栽研究中发现，在6种化学型中，有两种化学型的tanacetaria菌落生长速度显著快于其他化学型，而其中一种（不同）化学型的菌落在天敌环境下的存活率显著低于其他化学型。我们发现，化学多样性至少部分地介导了普通瓢虫及其昆虫群落中蚜虫吸引或驱避、自下而上和自上而下的过程，我们目前的重点是将这些单独的过程联系起来。在第二个资助期，我们的目标是继续研究蚜虫群落与化学多样性（P5）的关系，重点研究其对专业抗虫蚜虫M. fuscoviride和Lasius niger蚂蚁之间动态的影响。我们将结合田间观察和盆栽实验来揭示化学多样性，特别是挥发物（P1, P2）在驱动蚂蚁访问中的作用，以及对镰刀蚜性能和与其他蚜虫物种的种间竞争的影响。此外，我们的目的是利用实地实验来调查地下化学多样性的后果。我们将研究样地化学型丰富度对土壤群落的影响，即土壤栖息线虫、微型和大型节肢动物和内生真菌（P4）。在盆栽试验中，我们将测试不同样地水平化学型丰富度的土壤和不同化学多样性的同种响应植物对植物-土壤反馈、食草动物和传粉者（P5）的影响。P7将通过量化草食和草食适应度，为化学多样性-可塑性实验做出贡献。

In the first funding phase, our goal was to manipulate chemodiversity of Tanacetum vulgare at the plant community level, to study the interactions between these plants and aphids. Therefore, we created a chemodiversity field experiment - totaling 84 plots and 504 plants - in which the plot-level chemotype richness of Tanacetum vulgare terpenoid chemotypes (determined by P5 and P6) ranged from one to six. We sampled insect communities (focusing on aphids and predators) and plant growth parameters as well as headspace volatile organic compounds (with P1 and P2). Field insect and volatile data are currently under analysis, but preliminary analyses show effects of plot-level chemotype richness on aphid colonisation, particularly a positive effect on Metopeurum fuscoviride abundance. Under laboratory conditions, we performed pairwise choice assays for the used chemotypes, using two aphid species specialised on T. vulgare, Macrosiphoniella tanacetaria and Uroleucon tanaceti (with P5). We found that chemotypes affect choice behaviour in both species and that terpenoid diversity tends to repel, while total terpenoid concentration tends to attract M. tanacetaria. Bottom-up and top-down pot studies on the T. vulgare chemotypes revealed that M. tanacetaria colonies grow significantly faster on two out of six chemotypes, while colony survival when exposed to natural predators was significantly lower on one (different) chemotype. We showed that chemodiversity mediates – at least partly – aphid attraction or repellence, bottom-up and top-down processes in T. vulgare and its insect communities, and our current focus is to link these individual processes in the study system. In the second funding period, our goal is to continue to investigate aphid communities in relation to chemodiversity (with P5) with a focus on its effects on the dynamics between the specialist ant-tended aphid M. fuscoviride and Lasius niger ants. We will combine field observations in our common garden with pot experiments to unravel the role of chemodiversity, and particularly volatiles (with P1, P2), in driving ant visitation and consequences for M fuscoviride performance and interspecific competition with other aphid species. In addition, our aim is to use the field experiment to investigate consequences of chemodiversity belowground. We will study the consequences of plot-level chemotype richness on soil communities, i.e. soil-dwelling nematodes, micro- and macro-arthropods and endophytic fungi (with P4). In a pot experiment, we will test the consequences of soils from plots differing in plot-level chemotype richness and conspecific response plants differing in chemodiversity for plant-soil feedbacks, herbivores and pollinators (with P5). P7 will contribute to the chemodiversity-plasticity experiment by quantifying herbivory and herbivore fitness.