Leaf quality and insect herbivory in model tropical plant communities after long-term exposure to elevated atmospheric CO2
✍ Scribed by J. A. Arnone; J. G. Zaller; Ch. Körner; C. Ziegler; H. Zandt
- Publisher
- Springer-Verlag
- Year
- 1995
- Tongue
- English
- Weight
- 785 KB
- Volume
- 104
- Category
- Article
- ISSN
- 0029-8549
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✦ Synopsis
Results from laboratory feeding experiments have shown that elevated atmospheric carbon dioxide can affect interactions between plants and insect herbivores, primarily through changes in leaf nutritional quality occurring at elevated CO 2. Very few data are available on insect herbivory in plant communities where insects can choose among species and positions in the canopy in which to feed. Our objectives were to determine the extent to which CO2-induced changes in plant communities and leaf nutritional quality may affect herbivory at the level of the entire canopy. We introduced equivalent populations of fourth instar Spodoptera eridania, a lepidopteran generalist, to complex model ecosystems containing seven species of moist tropical plants maintained under low mineral nutrient supply. Larvae were allowed to feed freely for 14 days, by which time they had reached the seventh instar. Prior to larval introductions, plant communities had been continuously exposed to either 340 gl CO 2 1-1 or to 610 gl CO 2 1-1 for 1.5 years. No major shifts in leaf nutritional quality [concentrations of N, total non-structural carbohydrates (TNC), sugar, and starch; ratios of: C/N, TNC/N, sugar/N, starch/N; leaf toughness] were observed between CO 2 treatments for any of the species. Furthermore, no correlations were observed between these measures of leaf quality and leaf biomass consumption. Total leaf area and biomass of all plant communities were similar when caterpillars were introduced. However, leaf biomass of some species was slightly greater -and for other species slightly less (e.g. Cecropia peltata) -in communities exposed to elevated CO 2. Larvae showed the strongest preference for C. peltata leaves, the plant species that was least abundant in all communities, and fed relatively lit-