Enemy release, biotic resistance and the success of invasive forest insects

全球化确保了入侵物种将继续到达、建立并对我们的生态系统造成重大破坏，导致重大的全球变化。我的研究旨在通过提高对影响天敌调节其种群的群落相互作用的理解，提高我们管理这些物种的能力。NSERC-DG的资助将使我的研究小组能够进行这里提出的初级生态研究，这些研究将阐明驱动这些变化的关键机制，以及在森林中缓解这些变化的潜在途径。物种相互作用是敌人释放和生物抗性理论的基础，也是我研究的主要内容。我们非常需要了解入侵森林的这一过程，我的研究项目是加拿大为数不多的积极研究入侵物种和生物控制领域的学术团体之一。**最近引入加拿大的几种主要森林昆虫（翡翠灰螟（EAB），亚洲长角甲虫（ALHB）， Sirex木蜂）使我们能够比较本地和外来的天敌复合物，并探索这些群落影响寄主死亡率和害虫入侵的机制。我最出名的贡献是在森林系统中增加了用于生物控制的本地天敌，在该领域被广泛引用的工作仍然是明确的，然而，我目前的研究探索了关于本地物种位移的假设，以便更好地了解入侵过程。我的具体兴趣是在引入外来物或通过森林操纵的天敌的社区模式。在这里，我研究了敌人释放和生物抗性假设，作为新物种在森林中建立时观察到的群落模式的可能解释。我的问题是，哪种假设能更好地解释两个密切相关的甲虫系统中的敌人攻击和宿主生产力？一种是本地的（东部松刻花甲虫，ippini），另一种是最近从欧洲引进的（Tomicus piniperda）。这两种树皮甲虫都是同域的韧皮部捕食者，攻击加拿大东部的本地和外来松树。**使用这个外来-本土模型系统，我将测试这两个假设，关于捕食水平，寄生，专业化，以及敌人和伙伴的社区多样性。我预测，与欧洲相比，北美本土甲虫（Ips）的天敌将更加多样化和专业化，并且比非本土甲虫（Tomicus）的密度更大，这将为敌人释放假说提供支持。生物地理和生物成因数据将通过甲虫密度的梯度来量化敌人存在的程度，并可以解释甲虫的死亡率和生产力。通过比较在控制密度和控制生物相互作用下与这些甲虫相关的群落（天敌、共生者和竞争对手）和模式，我将能够建立最好的解释机制。**这项初步研究的结果将增加我们对我国森林入侵动态的理解，并在应用层面上有助于指导外来昆虫物种的管理策略。它们将引起科学家、生物防治研究人员、管理入侵物种的决策者以及关注这些物种的生态和经济影响的公众和森林工业的兴趣。我的提案要求资金不仅用于支持支持生态系统恢复过程的基础知识，而且还用于为加拿大最重要的可再生资源——我们的森林——在入侵生物学方面实现独特和互补的HQP能力。

Globalization ensures that invasive species will continue to arrive, establish, and cause significant disruption in our ecosystems, leading to major global change. My research aims to increase our ability to manage such species through improved understanding of community interactions that affect the natural enemies regulating their populations. NSERC-DG funding will enable my research team to conduct the primary ecological studies proposed here, work that will elucidate key mechanisms driving these changes, as well as potential avenues for their mitigation in forests. Species interactions underpin the theories of enemy release and biotic resistance, and are a major thrust of my research. There is a great need to understand such processes in invaded forests, and my research program represents one of the few academic groups in Canada actively working in this area of invasive species and biological control.**Recent introductions into Canada of several major forest insects (emerald ash borer (EAB), Asian long-horned beetle (ALHB), Sirex woodwasps) allow us to compare native and exotic natural enemy complexes, and to explore mechanisms by which these communities affect host mortality and pest invasion. I am best known for my contributions augmenting native natural enemies for biological control in forested systems, widely cited work still definitive in the field, however, my current research explores hypotheses around displacement of native species in order to better understand the invasion process. My specific interests are in community patterns of natural enemies following the introduction of exotics or through forest manipulation. Here, I investigate the enemy release and biotic resistance hypotheses as possible explanations for the community patterns observed as a new species establishes in the forest. I ask the question, which hypothesis better explains enemy attack and host productivity in two closely-related beetle systems; one indigenous (eastern pine engraver beetle, Ips pini), and one recently introduced from Europe (Tomicus piniperda). Both bark beetles are sympatric phloem-feeders attacking native and exotic pines across eastern Canada.**Using this exotic-indigenous model system, I will test these two hypotheses with respect to levels of predation, parasitism, specialization, and community diversity of enemies and associates. I predict that in contrast to Europe, natural enemies of the indigenous North American beetle (Ips) will be both more diverse and specialized, and occur at greater densities than those on the nonindigenous beetle (Tomicus), and that this will lend support for the enemy release hypothesis. Biogeographic and ontongenic data will be derived across a gradient of beetle densities to quantify the degree to which enemies are present, and can account for beetle mortality and productivity. By comparing communities (natural enemies, mutualists, and competitors) and patterns associated with these beetles under manipulated densities and controlled biotic interactions, I will be able to establish the best explanatory mechanism. **Results from this primary research will add to our understanding of invasion dynamics in our forests, and at the applied level, help to direct management strategies for alien insect species. They will be of interest to scientists, bio-control researchers, as well as policy-makers who regulate invasive species and the public and forest industry concerned with the ecological and economic effects of such species. My proposal requests funding to fuel not only basic knowledge underpinning processes of ecosystem resilience, but also to achieve unique and complementary HQP capacity in invasion biology for Canada's most significant renewable resource, our forests.