Community consequences of introducing a biological control agent

在英国、欧洲大部分地区和世界其他地区，入侵杂草正在通过排斥本地物种、减少生物多样性和取消生态系统服务来破坏自然栖息地。一些入侵的杂草甚至会破坏建筑物的地基，造成结构问题。仅英国经济每年的成本就接近20亿GB，这突显出它们是控制或清除的关键目标。控制这些杂草的努力也是有问题和昂贵的，部分原因是缺乏控制措施，部分原因是植物传播的旺盛性质和植物根深蒂固的根深蒂固。其中一种问题植物是凤仙花(喜马拉雅香树)，它现在是英格兰和威尔士河岸(河滨)系统最常见的非本土植物物种。这种植物严重减少了当地植物和昆虫的生物多样性，而且价格昂贵，很难控制，因为除草剂不能在水道附近使用。巴萨姆植物在冬季死亡，使暴露的地区容易受到侵蚀，而夏季人口堵塞水道，增加洪水发生的可能性。DEFRA选择巴萨姆作为生物防治的目标杂草，强调了这项研究的重要性。2014年7月，CABI获得了部长批准，可以释放锈菌Puccinia komarovii var。在英国的试验点，在巴基斯坦和印度发现了一种喜马拉雅香脂的病原体--腺柳花科。这是欧洲第一次批准释放非本土真菌病原体。因此，它提供了一个独特的机会来确定锈菌释放对工厂和它入侵的社区的影响。重要的是不仅要研究哪些因素影响田间锈病的药效，而且还要研究当地植物群落如何随着杂草种群的减少而恢复。这项提议是由CABI、皇家霍洛威、伦敦大学和雷丁大学联合提出的。我们将共同监测锈菌的释放，确定影响其在田间建立的因素，并发现受入侵的社区在移除香脂后如何恢复。我们将与DEFRA一起进行这项研究，DEFRA承诺提供资金监测锈菌的释放。我们将进行一系列实验，以检查土壤中的有益真菌(称为丛枝菌根)对锈菌感染的影响。菌根为植物提供必要的营养，一些物种已知会增加对叶部病原体的敏感性。我们还将检查香脂植物的叶组织，因为这些组织也含有真菌(称为内生菌)。一项新的研究表明，生活在植物表面和植物内部的微生物可能对潜在的入侵病原体具有抗微生物作用。关键是要确定我们是否可以操纵植物的生长条件，以最大限度地提高铁锈的效率，无论是通过鼓励有助于铁锈的微生物，还是通过消除有害微生物的条件。这是一个独特的机会，可以发现本地植物、昆虫和土壤微生物群落在除草后如何开始恢复。生物防治通常是关于降低目标生物体的健康或性能，到目前为止，人们普遍认为，一个原生的、多样化的群落很容易建立起来。然而，我们知道香脂以某种方式改变了土壤，严重阻碍了其他植物的生长。因此，这项研究的一个关键结果将是确定我们如何利用有益的微生物来允许本地植物重新定居。特别令人兴奋的是，我们希望用来帮助锈病防治的菌根真菌也有潜力帮助本地植物生长，因此我们将能够开发出一种独特的双头策略，对这种杂草的控制产生真正的影响。

In the UK, and much of Europe and the rest of the world, invasive weeds are destroying natural habitats through exclusion of native species, reduction of biodiversity, and removal of ecosystem services. Some invasive weeds even damage the groundwork of buildings, causing structural problems. The costs to the UK economy alone totals almost £2billion per year highlighting them as key targets for control or removal. Efforts to control these weeds is also problematic and expensive, partly due to lack of control measures and partly because of the vigorous nature of the plant spread and deep-rooted establishment of the plants. One of these problem plants is Impatiens glandulifera (Himalayan Balsam), which is now the most commonly occurring non-native plant species on riparian (riverside) systems in England and Wales. The plant severely reduces native plant and insect biodiversity and is expensive and difficult to control, because herbicides cannot be used near water courses. Balsam plants die off in winter, leaving exposed areas susceptible to erosion, while summer populations choke water courses, increasing the likelihood of flooding.DEFRA selected Balsam as target weed for biological control, emphasising the importance of this research. In July 2014, CABI received Ministerial approval to release the rust fungus Puccinia komarovii var. glanduliferae, a pathogen of Himalayan Balsam found in Pakistan and India, at trial sites in the UK. This is the first approved release of a non-native fungal pathogen anywhere in Europe. It therefore provides a unique opportunity to determine the impact of the rust release on the plant and the communities it has invaded. It is important not just to examine what factors affect the efficacy of the rust in the field, but also how native plant communities recover as weed populations decline. This proposal is a joint one involving CABI, Royal Holloway, University of London and the University of Reading. Together, we will monitor rust release, determine the factors that affect its establishment in the field and discover how invaded communities recover after balsam removal. We will conduct this research alongside DEFRA, who have pledged money to monitor rust release.We will carry out a series of experiments to examine the impact of soil-dwelling beneficial fungi (termed arbuscular mycorrhizas) on rust infection. Mycorrhizas provide plants with essential nutrients and some species are known to increase susceptibility to foliar pathogens. We will also examine the foliar tissues of balsam plants, as these also contain fungi (termed endophytes). New research is emerging to suggest that microbes living on plant surfaces and inside plants could have anti-microbial effects on potential invading pathogens. It is critical to determine whether we can manipulate the plant's growth conditions to maximise the efficiency of the rust, either through encouraging microbes that help the rust or removing conditions for detrimental microbes.This is a unique opportunity to discover how the native plant, insect and soil microbial communities start to recover after weed removal. Biocontrol is usually about reducing the health or performance of target organisms and to date it has generally been assumed that a native, diverse community will readily establish. However, we know that balsam somehow alters the soil to severely reduce growth of other plants. Thus, a key outcome of the study will be to determine how we can use beneficial microbes to allow native plants to recolonise. A particularly exciting part is that the mycorrhizal fungi which we hope to use to aid rust efficacy also have the potential to help native plants to grow, thus we will be able to develop a unique, double-headed strategy to have a genuine impact on the control of this weed.