Effects of the exotic shrub Lonicera maackii on the plant animal interactions in the invaded habitat

Invasive plants are an economical, political, social, and ecological problem. Some invasive species are a serious concern for society because some of them are diseases, some are agricultural pests, and some become major threats to the ecosystems. Most studies with invasive species are limited because they measure only the impact of the invasion via direct pathways. Unfortunately, the potential for non-native plant species to alter ecosystem functions via indirect pathways mediated by interactions with animals just recently became broadly recognized. This research investigates the interactions of Amur honeysuckle with native fauna and how these interactions indirectly affect other trophic levels of the local community and ecosystem functioning. Specifically, the study uses an experimental approach to verify whether the fruits and cover provided by the invasive honeysuckle modify mammals’ foraging behavior and abundance, and how this effect on mammals could be linked with seedling recruitment, tick abundance, and ticks’ pathogens. The results show that removal of honeysuckle cover, rather than changes in fruit resources, is linked with a reduction in the activity of important seed consumers (e.g. mice and deer) and mesopredators (e.g. racccon and opossum). They also show that the abundance of the white-footed mouse Peromyscus leucopus responds positively to honeysuckle’s cover and fruits. Moreover, the study provides evidence that the effects of invasive shrub on mammals may be translated into differential seedling predation, higher incidence of ticks, and increased human risk of exposure to ehrlichiosis, an emerging infectious disease caused by bacterial pathogens transmitted by the lone star tick. This study reinforces the idea that the effects of invasive plants on native communities extend beyond direct competition with native plants, and that the indirect effects should also be taken into consideration when measuring the impact of exotic plants