DISSERTATION RESEARCH: Effects of a Hybrid Host Plant on Diversity and Abundance of Insects

人类经常长距离传播生物，并使曾经在地理上分离的物种相互接触。如果相似的物种在接触时能够杂交，就会产生杂交物种。因此，杂交正在增加，但其生态后果尚不清楚。食草昆虫对杂交植物的反应通常与对原始植物的反应不同。昆虫对杂交种的反应影响了昆虫食草动物的丰度和以昆虫为食的其他生物的成功。本研究调查了杂交植物的抗性现象，即在杂交植物上发现的食草动物比在原始亲本物种上发现的少。在香蒲（Typha）杂交种上有杂交抗性的记录。在杂交种上，芦苇蛾的数量较少，但产生这种抗性的原因尚不清楚。该项目的第一个目标是确定除飞蛾以外的其他昆虫物种对杂交昆虫是否有类似的反应。第二个目标是发现为什么飞蛾在杂交种上数量较少。有两种可能：(1)雌蛾不识别杂交种，避免在杂交种上产卵；(2)幼虫在杂交种上成活率差。这项研究的结果将有助于预测和管理其他杂交事件的结果。人们对杂交香蒲的担忧也越来越多，因为它是一种咄咄逼人的竞争对手，排斥了湿地上的其他植物。草食抗性可能有助于杂交种的竞争力，并降低杂交种占主导地位的沼泽作为其他生物栖息地的价值。

Humans often transport organisms over long distances and bring into contact species that were once geographically separated. If similar species can interbreed when in contact, hybrids will be created. Hybridization is therefore increasing, but the ecological consequences are not well understood. Herbivorous insects often respond to hybrid plants differently than they would to the original plant species. The response of insects to hybrids affects the abundance of insect herbivores and the success of other organisms that feed on the insects.This research investigates the phenomenon of hybrid resistance, in which fewer herbivores are found on hybrid plants than on the original parental species. Hybrid resistance has been documented on hybrids of cattail species (Typha). The moth Limnaecia phragmitella is less abundant on hybrids but the reasons for this resistance are not known. The first objective of this project is to determine whether insect species other than the moth respond in a similar way to hybrids. The second objective is to discover why moths are less abundant on hybrids. There are two possibilities: (1) Female moths do not recognize hybrids and avoid laying eggs on them, and (2) Larval survival on hybrids is poor. The results of this study will help predict and manage the outcomes of other hybridization events. There is also growing concern over the hybrid cattail, because it is an aggressive competitor and excludes other plants in wetlands. Herbivore resistance may contribute to the hybrids' competitiveness and lower the value of hybrid-dominated marshes as habitat for other organisms.