Resource allocation to defence and growth are driven by different responses to generalist and specialist herbivory in an invasive plant
Article first published online: 26 JUL 2010
© 2010 The Authors. Journal compilation © 2010 British Ecological Society
Journal of Ecology
Volume 98, Issue 5, pages 1157–1167, September 2010
How to Cite
Huang, W., Siemann, E., Wheeler, G. S., Zou, J., Carrillo, J. and Ding, J. (2010), Resource allocation to defence and growth are driven by different responses to generalist and specialist herbivory in an invasive plant. Journal of Ecology, 98: 1157–1167. doi: 10.1111/j.1365-2745.2010.01704.x
- Issue published online: 4 AUG 2010
- Article first published online: 26 JUL 2010
- Received 21 January 2010; accepted 18 June 2010 Handling Editor: Sedonia Sipes
- biological control;
- Chinese tallow;
- Cnidocampa flavescens;
- evolution of increased competitive ability;
- Gadirtha inexacta;
- invasion ecology;
1. Invasive plants often have novel biotic interactions in their introduced ranges. These interactions, including less frequent herbivore attacks, may convey a competitive advantage over native plants. Invasive plants may vary in defence strategies (resistance vs. tolerance) or in response to the type of herbivore (generalists vs. specialists), but no study to date has examined this broad set of traits simultaneously.
2. Here, we examined resistance and tolerance of Chinese tallow (Triadica sebifera) populations from the introduced and native ranges to generalist (Cnidocampa flavescens) and specialist herbivores (Gadirtha inexacta) in the native range.
3. In a field common-garden test of resistance, caterpillars of each species were raised on plants from native and invasive populations. We found the specialist grew larger on and consumed more mass of invasive plant populations than native populations, while the generalist showed the same performance between them. The results were consistent with our laboratory bioassay using excised leaves. Chemical analyses showed that the invasive plants had lower tannin content and higher ratio of carbohydrate to protein than those of their native counterparts, suggesting that plants from invasive populations have altered chemistry that has a larger impact on specialist than on generalist resistance.
4. To test for differences in herbivore tolerance, plants were first defoliated by specialist or generalist herbivory and then allowed to regrow for 100 days in a field common garden. We found that plants from invasive populations had greater herbivore tolerance than native populations, especially for tolerance to generalists. They also grew more rapidly than native counterparts in the absence of herbivory.
5. Synthesis. The results of these experiments indicate that differences in selective pressures between ranges have caused dramatic reductions in resistance to specialist herbivores and those changes in plant secondary chemistry likely underlie these differences. The greater tolerance of invasive populations to herbivory appears to at least partly reflect an increase in growth rate in the introduced range. The greater tolerance to generalist herbivores suggests the intriguing possibility of selection for traits that allow plants to tolerate generalist herbivores more than specialist herbivores.