Abstract: Invasive species threaten ecosystems and economies. Invasive plants are economically harmful because they diminish agricultural output and are expensive to control. The U.S. alone loses about $9.6 billion annually due to invasive plants. In eastern North American woodlands, exotic shrubs are displacing native plants and transforming understory communities. The displacement of native plants by these non-natives may reduce the resources available to higher trophic levels by not supporting arthropod communities as well as native plants do. Invasive plants may either be unrecognizable to native herbivores or possess defenses to which these herbivores are poorly adapted. Despite the conceptual understanding of invasive shrubs’ potential to transform forest communities, little research has focused on characterizing the arthropod communities they support or their impact on higher trophic levels. To address this gap, I compared arthropod community diversity, abundance, and composition on two invasive shrubs in southwestern Ohio: Amur honeysuckle (Lonicera maackii) and border privet (Ligustrum obtusifolium), to two native plant taxa: blackhaw (Viburnum prunifolium) and ash saplings (Fraxinus spp.). I assessed the abundance, diversity, and structure of arthropod communities hosted by each plant species over a growing season in 11 forested sites in southwestern Ohio. There were significant differences in terms of the abundance and diversity of arthropod communities hosted by these plants. Lo. maackii hosted a depauperate arthropod community, with fewer individuals and species per cubic meter of foliage than its native counterpart, V. prunifolium. Primarily, this was driven by the poor herbivore community on Lo. maackii. Contrary to expectations, Li. obtusifolium hosted a larger and more diverse community than Fraxinus spp. Surprisingly, the herbivore community on Li. obtusifolium was similar or greater in abundance and diversity than that of Fraxinus spp. This suggests Li. obtusifolium may not contribute to arthropod community decline in the short term. Additionally, there was a significant, albeit small, effect of host species on the family-level arthropod community composition for both native-invasive pairs. Invasive plants may suppress community diversity and ecosystem services, but the degree likely varies based on the invasive species in question and on which natives they displace.
