DISSERTATION RESEARCH: Assessing multiple mechanisms of belowground enemy release for an invasive dune-building grass species

了解入侵的根本原因对于尽量减少其负面影响至关重要。非原生植物在其原生地范围内逃避控制其生长的天敌时可能成为入侵植物，这被称为天敌释放假说。这些植物的天敌既存在于地上也存在于地下，尽管地下的天敌通常研究得较少。植物寄生线虫生活在土壤中，以植物根部为食，可以控制本地植物的生长。 然而，很少有人知道线虫的取食偏好，以及入侵植物是否逃脱损害，由于这些偏好。此外，植物寄生线虫有各种不同的进食策略。有些有一个一般的策略，在根表面进食，而另一些有一个更专门的方法，钻入根组织，在根内进食。这些取食策略的差异可能会影响入侵植物入侵新区域时释放敌人的强度。这项研究将提供深入了解入侵植物及其逃避天敌，同时为EPSCoR状态的本科生提供宝贵的研究机会。由于这项工作的重点是在五大湖沙丘的入侵草，这项工作将有助于更好地了解五大湖沿海生态和管理。该项目旨在了解两个因素相关的敌人释放-取食偏好的植物寄生线虫和植物生长的反应释放从通才和专门的敌人。以沙生赖草入侵短舌沙草（Ammophila breviligulata）为主的沙丘作为模型系统，本研究将解决两个基本问题：植物寄生线虫对本地植物的取食偏好是否高于非本地植物？非本土植物是否从专业食草动物那里获得的释放量大于一般食草动物？这些问题将通过一系列实验室和温室实验来回答。这些结果将揭示线虫是否可以检测植物根部，表现出对某些植物的偏好，以及这些偏好是否随摄食专业化而变化。在配套温室实验中，将评估植物对线虫摄食专门化和密度的反应。这项工作的结果将扩大了解地下食草动物在释放敌人在非本地植物入侵的作用。

Understanding the reasons underlying invasion is critical for minimizing their negative impacts. Non-native plants may become invasive when they escape their natural enemies that control their growth in their native range, which is called the enemy release hypothesis. These natural enemies of plants occur both above- and belowground, though belowground enemies have generally been less well studied. Plant-parasitic nematodes live in soil, feed on plant roots, and can control the growth of native plants. However, little is known about feeding preferences of nematodes, and whether invasive plants escape damage due to these preferences. Additionally, plant-parasitic nematodes have a variety of different feeding strategies. Some have a general strategy of feeding on the root surface, while others have a more specialized approach of burrowing into the root tissue to feed inside the root. Differences in these feeding strategies may affect the strength of enemy release that invasive plants experience when they invade into new areas. This research will provide insights into invasive plants and their escape from natural enemies while providing valuable research opportunities to undergraduate students in an EPSCoR state. Because this work focuses on an invasive grass in the Great Lakes sand dunes, this work will contribute to a better understanding of Great Lakes coastal ecology and management. This project seeks to understand two factors related to enemy release - feeding preferences of plant-parasitic nematodes and plant growth responses to release from generalist and specialized enemies. Using invasion by Leymus arenarius (sand ryegrass) into Ammophila breviligulata (American beachgrass) dominated sand dunes as a model system, this research will address two basic questions: Do plant-parasitic nematodes exhibit feeding preferences for native plants over non-native plants? Do non-native plants experience greater release from specialist herbivores over generalist herbivores? These questions will be answered using a series of lab and greenhouse experiments. These results will reveal whether nematodes can detect plant roots, exhibit preferences for certain plants, and whether these preferences vary with feeding specialization. In a companion greenhouse experiment, plant responses to nematode feeding specialization and density will be assessed. Results from this work will broaden the understanding of the role belowground herbivores play in enemy release during non-native plant invasion.