An exotic herbivore reinforces competition between exotic and native plants

Despite increasing evidence that herbivore-mediated indirect effects play a major role in plant competition, it is unclear how and when they contribute to plant invasiveness. The outcomes of herbivore-mediated indirect effects are primarily dependent on the environment and have complex interactions with the direct interactions between plants. 
We evaluated the herbivore-mediated indirect effects of Solidago altissima (Asteraceae) on other co-occurring native Asteraceae species at multiple sites in a native range [the United States (US)] and in an introduced range (Japan) using common garden experiments. We examined the effect of S. altissima on herbivore damage, aboveground vegetative and reproductive traits of the co-occurring Asteraceae species at sites with different densities of a herbivore, the lace bug, Corythucha marmorata, which is native to the US and introduced in Japan.
We observed increased lace bug herbivory in plants grown with S. altissima in Japan but decreased la...