Insect Science (2012) 00, 1–6, DOI 10.1111/j.1744-7917.2012.01524.x ORIGINAL ARTICLE Invading from the garden? A comparison of leaf herbivory for exotic and native plants in natural and ornamental settings Stephen F. Matter, Jessica R. Brzyski, Christopher J. Harrison, Sara Hyams, Clement Loo, Jessica Loomis, Hannah R. Lubbers, Leeann Seastrum, Trevor I. Stamper, Adam M. Stein, Richard Stokes and Brandy S. Wilkerson Department of Biological Sciences, University of Cincinnati, Cincinnati, USA Abstract The enemies release hypothesis proposes that exotic species can become in- vasive by escaping from predators and parasites in their novel environment. Agrawal et al. (Enemy release? An experiment with congeneric plant pairs and diverse above- and below-ground enemies. Ecology, 86, 2979–2989) proposed that areas or times in which damage to introduced species is low provide opportunities for the invasion of native habitat. We tested whether ornamental settings may provide areas with low levels of herbivory for trees and shrubs, potentially facilitating invasion success. First, we compared levels of leaf herbivory among native and exotic species in ornamental and natural settings in Cincinnati, Ohio, United States. In the second study, we compared levels of herbivory for invasive and noninvasive exotic species between natural and ornamental settings. We found lower levels of leaf damage for exotic species than for native species; however, we found no differences in the amount of leaf damage suffered in ornamental or natural settings. Our results do not provide any evidence that ornamental settings afford additional release from herbivory for exotic plant species. Key words enemies release hypothesis, forest, herbivory, host plant, suburban, urban Introduction The enemies release hypothesis postulates that exotic plants are subject to lower levels of herbivory (or nat- ural enemies in general) than are native species (Elton, 1958; Wolfe, 2002; Callaway et al., 2004; Colautti et al., 2004). Lower levels of herbivory are thought to arise from a loss of specialist enemies from the exotic species’ na- tive range and a lack of adapted herbivores in its intro- duced range. Reduction in damage is assumed to translate into higher survivorship and reproductive output of exotic species relative to natives, facilitating invasion (Keane & Crawley, 2002). Studies of the enemies release hypotheses Correspondence: Stephen F. Matter, University of Cincin- nati, Department of Biological Sciences Cincinnati, OH 45221- 0006, USA. Tel: (513) 556–9768; fax: (513) 556–5299; email: mattersf@uc.edu have shown that release from herbivory is not a general phenomenon for all exotics (Agrawal & Kotanen, 2003). However, those species that do become invasive of- ten have lower levels of herbivory than noninvasive species (Cappuccino & Carpenter, 2005, but see Keane & Crawley, 2002). Despite this support for the enemies re- lease hypothesis, mechanisms allowing invasive species to escape from herbivory remain elusive (Lind & Parker, 2010; Hornoy et al., 2011). Many studies have shown that damage from insect her- bivores can be context specific, varying in both space and time. Agrawal et al. (2005) argued that areas where or times when damage to introduced species is low, may provide windows of opportunity for the invasion of native communities. Here, we test one such spatial window, or- namental settings. Because these areas are rich in exotic species and potentially low in herbivorous insects (Raupp et al., 2010), ornamental settings may provide an environ- ment conducive for invasion. C  2012 The Authors Insect Science C  2012 Institute of Zoology, Chinese Academy of Sciences 1