Most invasive plant species have been introduced to their new ranges without the full suite of natural enemies with which they co-evolved. In the absence of specialist herbivores, invasive species may reallocate resources from defence to growth, reproduction or both. However, the enemy release, and the associated fitness gain, might be temporary as native herbivores tend to accumulate on non-native species over time. While the potential effects of the initial enemy release have been well studied, the consequences of any resumption of herbivory are poorly understood. A recent research result released by Prof. DING Jianqing and his research group at Wuhan Botanical Garden (WBG) may provide insights into this question.

To evaluate the impact of re- or novel-associated herbivores on plant tolerance, WBG scientists conducted a greenhouse experiment with Alternanthera philoxeroides as study system. A. philoxeroides is one of the most widespread invasive plants in China and is attacked both by a specialist herbivore introduced from the native range, Agasicles hygrophila, and a native beetle Cassida piperata Hope which has formed a new association. However, these insects are not found throughout the invaded range. To test the effect of the history of population exposure to herbivory on compensatory ability, plants were cultured from 14 populations around China that differed in whether A. hygrophila or C. piperata were present. The result demonstrates that plants from populations with prior exposure to herbivory (of any kind) accumulated more root mass than populations without prior exposure, indicating that prior exposure to insects can stimulate plant compensation to herbivory.

This study has broad implications for biological control and insect-plant interaction. The research result has been published in Biological Invasions entitled “History of exposure to herbivores increases the compensatory ability of an invasive plant”. This research was funded by the Knowledge Innovation Program of Chinese Academy of Sciences and the National Science Foundation of China.

Article link: http://www.springerlink.com/content/b241566h0v415j6q/ 

Author contact: Prof. DING Jianqing

Tel: +86-27-87510970

Email: ding@wbgcas.cn 

Wuhan Botanical Garden of Chinese Academy of Sciences