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

我的研究旨在通过提高对影响天敌调节森林取食昆虫的因素的理解，提高我们管理森林昆虫的能力。 具体来说，我探讨有关的问题，人口死亡率和昆虫天敌的社区多样性，重点是了解和操纵本地寄生虫和捕食者。 最近引进到加拿大的几个主要的森林昆虫（祖母绿灰螟，亚洲长角甲虫，Sirex木蜂），使我们能够比较本地和外来的天敌的复合体，并探讨这些社区影响主机死亡率和害虫入侵的机制。 我目前的工作是测试外来物种和群落如何取代本土物种的假设，以便更好地了解森林中的入侵过程。 在这个建议中，我测试的敌人释放假说（ERH），更具体地说，在非本土物种假说（ENRS）的敌人减少。 我问的问题，ENRS解释模式的敌人攻击和主机生产力的土著（IPS）和外来（切梢小蠹）树皮甲虫，或有证据表明生物抗性（BR）。 东方松刻甲（I. pini）是NA的原生种，而T. Piniperda（另一种食韧皮部的小煤炱）是在20世纪90年代从欧洲引进的。后者已经建立;两者都是同域的，并在安大略南部的林分中以相同的本地松树（P. strobus，P. resinosa，P. banksiana）和外来松树（P. sylvestris）为食。 使用这种异国情调/土著树皮甲虫系统，我将测试ERNS方面的捕食水平，寄生，和社区多样性的敌人和联营公司对这两种甲虫。 我预测，土著甲虫的敌人将更加多样化，并在更大的密度比那些非土著Tomicus发生。 生物地理和ontogenic数据将跨梯度的甲虫密度，以量化的程度，敌人是存在的，并占甲虫死亡率和生产力。这些结果将增加我们目前对入侵动态的理解，并在应用层面上，有助于指导外来入侵森林昆虫物种的管理策略。

My research aims to increase our ability to manage forest insects through improved understanding of factors that affect natural enemies regulating forest-feeding insects. Specifically, I explore questions related to population mortality and community diversity of insect natural enemies, with focus on understanding and manipulating native parasitoids and predators. Recent introductions into Canada of several major forest insects (emerald ash borer, Asian long-horned beetle, Sirex woodwasps) enables us to compare the complexes of native and exotic natural enemies, and to explore mechanisms by which these communities affect host mortality and pest invasion. My current work tests hypotheses about how exotic species and communities displace native ones in order to better understand invasion processes in the forest. In this proposal, I test the enemy release hypothesis (ERH), more specifically, the enemy reduction in nonindigenous species hypothesis (ENRS). I ask the questions, does ENRS explain patterns of enemy attack and host productivity on indigenous (Ips) and exotic (Tomicus) bark beetles, or is there evidence for biotic resistance (BR). The eastern pine engraver beetle (I. pini) is native to NA, while T. piniperda (another phloem-feeding scolytid) was introduced from Europe during the 1990's. The latter has become established; both are sympatric and feed on the same native (P. strobus, P. resinosa, P. banksiana) and exotic (P. sylvestris) pines in stands across southern Ontario. Using this exotic/indigenous bark beetle system, I will test ERNS with respect to levels of predation, parasitism, and community diversity of enemies and associates on these two beetles. I predict that enemies of the indigenous beetle will be more diverse and occur at greater densities than those of the nonindigenous Tomicus. Biogeographic and ontongenic data will be derived across a gradient of beetle densities to quantify the degree to which enemies are present, and account for beetle mortality and productivity. These results will add to our current understanding of invasion dynamics, and at the applied level, help to direct management strategies for invasive alien forest insect species.