Multitrophic Impacts of an Emerging Invasive Plant

The invasion of novel habitats by non-native plant species is a worldwide problem with serious economical and ecological implications. Broad biotic and abiotic filters contribute to the overall invasibility of non-native species. Invasive plants have the ability to rapidly establish themselves and outcompete their native counterparts as result of their relationship with herbivorous arthropods. Because invasive plants displace native plants, reduce overall plant diversity, and alter vegetation structure, this can have cascading effects on insect herbivores, particularly those that rely on one or a few food plants, and arthropod predators. The genus Euonymus (Celastraceae) is comprised of 130 species. Euonymus alatus (burning bush) and Euonymus europaeus (spindle tree) are two non-natives that have been introduced to North American. Although these species are recognized as invasive in portions of the United States, very little is known about their invasion status, relationship with native herbivores, or community impacts. We sought to fill these gaps with a particular focus on burning bush. We first investigated the distribution of burning bush in Ohio and biotic and abiotic factors that contribute to its success through a citizen science self-reporting protocol. We then examined the relationship of burning bush and spindle tree to herbivorous arthropods through examining field herbivory, success in no-choice bioassays, and analysis of chemical defenses. Finally, we examined the cascading impacts of burning bush and overabundant deer on environmental characteristics and arthropod communities. Euonymus alatus was present across Ohio but more likely to be successful in locations with greater disturbance and resources. Burning bush and spindle tree are likely experiencing enemy release as both receive significantly less herbivory than a native congener. While both burning bush and spindle tree contained elevated levels of secondary metabolites, a generalist herbivore was able to use spindle tree as a host in no-choice bioassays, suggesting that spindle tree could be evading herbivory through unsuccessful host finding, and both could have novel weapons. Burning bush significantly changed arthropod community composition through alterations in environmental characteristics, and the introduction of white-tailed deer into these interactions more often than not, further intensified these alterations