| Title: | Leaf quality and insect herbivory in model tropical plant communities after long-term exposure to elevated atmospheric CO(2) |
| Author(s): | Arnone JA; Zaller JG; Korner C; Ziegler C; Zandt H; |
| Address: | "Department of Botany, University of Basel, Schonbeinstrasse 6, CH-4056, Basel, Switzerland. Department of Zoology, University of Basel, Rheinsprung 9, CH-4051, Basel, Switzerland" |
| ISSN/ISBN: | 1432-1939 (Electronic) 0029-8549 (Linking) |
| Abstract: | "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 CO(2)-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 mul CO(2) l(-1) or to 610 mul CO(2) l(-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 communites, and fed relatively little on plants species which were more abundant. Thus, our results indicate that leaf tissue quality, as described by these parameters, is not necessarily affected by elevated CO(2) under relatively low nutrient conditions. Hence, the potential importance of CO(2)-induced shifts in leaf nutritional quality, as determinants of herbivory, may be overestimated for many plant communities growing on nutrient-poor sites if estimates are based on traditional laboratory feeding studies. Finally, slight shifts in the abundance of leaf tissue of various species occurring under elevated CO(2) will probably not significantly affect herbivory by generalist insects. However, generalist insect herbivores appear to become more dependent on less-preferred plant species in cases where elevated CO(2) results in reduced availability of leaves of a favoured plant species, and this greater dependency may eventually affect insect populations adversely" |
| Keywords: | Carbon dioxide enrichment Feeding preference Leaf quality Mesocosms Spodoptera eridania; |
| Notes: | "PubMed-not-MEDLINEArnone, J A 3rd Zaller, J G Korner, Ch Ziegler, C Zandt, H eng Germany 1995/09/01 Oecologia. 1995 Sep; 104(1):72-78. doi: 10.1007/BF00365564" |
