Altered trophic interactions in a warming environment: insights into the population dynamics of eruptive herbivores

尽管气候变化对食草性昆虫的直接和间接影响预计是多种多样和复杂的，但迄今为止记录在案的最常见的变暖结果是它们的分布发生了变化。阐明与外来昆虫食草动物的分布变化和栖息地入侵相关的改变的营养相互作用可以为基本的生态过程提供重要的见解。对于容易发生种群剧烈波动和大范围暴发的物种，通过比较新生境和原生生境中的营养相互作用，可以确定影响其种群动态的关键因素，并量化影响其进化的选择压力。*由于环境变暖，山松甲虫(鞘翅目：弯翅虫科：刺甲科)已经历了戏剧性的范围扩大，进入以新宿主种群和物种为主的地区。利用这种昆虫食草动物作为模型系统，拟议的研究试图量化在本地森林和最近入侵的森林中爆发的森林昆虫的营养相互作用和种群动态。更具体地说，比较研究将量化(I)寄主-树木防御，(Ii)种间竞争相互作用，和(Iii)与天敌的相互作用对当地松材线虫的世代死亡率和动态的相对贡献。阔叶松)栖息地与新殖民的、可能在进化上幼稚的樟子松、短叶松(Pinus Bank Siana)和短叶松×短叶松杂交栖息地的对比。*最近，山松甲虫的活动范围扩大，这是北美第一个由本土喷发草食动物入侵栖息地的例子。这项研究利用6个相关的研究项目，将能够培训3名博士和3名硕士候选人，以及最多24名本科生(2篇理科论文，12名现场助理，10名实验室助理)，这项研究将对食草性昆虫种群的动态、昆虫-植物相互作用的进化以及爆发物种入侵栖息地的过程提供关键的见解。

Although the direct and indirect influences of climate change on herbivorous insects are expected to be variable and complex, the most commonly documented result of warming to date has been shifts in their distribution. Elucidation of altered trophic interactions associated with distributional changes and habitat invasion by an alien insect herbivore can provide important insights into fundamental ecological processes. For species prone to dramatic population fluctuations and widespread outbreaks, comparisons of trophic interactions in novel and native habitats make it possible to identify key factors influencing their population dynamics, and quantify the selective pressures shaping their evolution.***     As a consequence of a warming environment the mountain pine beetle (Coleoptera: Curculionidae: Scolytinae) has undergone a dramatic range expansion into regions dominated by novel host populations and species. Using this insect herbivore as a model system, the proposed research seeks to quantify the trophic interactions and population dynamics of an eruptive forest insect in native versus recently invaded forests. More specifically, comparative studies will quantify the relative contribution of (i) host-tree defenses, (ii) interspecific competitive interactions, and (iii) interactions with natural enemies to the generation mortality and dynamics of mountain pine beetle in native lodgepole pine (Pinus contorta var. latifolia) habitats versus newly colonized, and putatively evolutionarily naïve, lodgepole pine, jack pine (Pinus banksiana) and lodgepole x jack pine hybrid habitats.***     The recent range expansion by the mountain pine beetle comprises the first example in North America of significant habitat invasion by an indigenous eruptive herbivore. Using 6 interrelated research projects that will enable the training of 3 PhD and 3 MSc candidates, and up to 24 undergraduates (2 BSc theses, 12 field assistants, 10 lab assistants), this research will provide critical insights into the dynamics of herbivorous insect populations, the evolution of insect-plant interactions, and the processes of habitat invasion by eruptive species.********