Title Gypsy moth feeding in the canopy of a CO₂-enriched mature forest
Author/s Hättenschwiler S, Schafellner C
Year 2004
Journal Global Change Biology 10:1899-1908
Abstract Rising atmospheric carbon dioxide (CO₂) concentration is expected to change plant tissue quality with important implications for plant-insect interactions. Taking advantage of canopy access by a crane and long-term CO₂ enrichment (530 µmol mol⁻¹) of a natural old-growth forest (web-free air carbon dioxide enrichment), we studied the responses of a generalist insect herbivore feeding in the canopy of tall trees. We found that relative growth rates (RGR) of gypsy moth (Lymantria dispar) were reduced by 30% in larvae fed on high CO₂-exposed Quercus petraea, but increased by 29% when fed on high CO₂-grown Carpinus betulus compared with control trees at ambient CO₂ (370 µmol mol⁻¹). In Fagus sylvatica, there was a nonsignificant trend for reduced RGR under elevated CO₂. Tree species-specific changes in starch to nitrogen ratio, water, and the concentrations of proteins, condensed and hydrolyzable tannins in response to elevated CO₂ were identified to correlate with altered RGR of gypsy moth larvae. Our data suggest that rising atmospheric CO₂ will have strong species-specific effects on leaf chemical composition of canopy trees in natural forests leading to contrasting responses of herbivores such as those reported here. A future change in host tree preference seems likely with far-ranging consequences for forest community dynamics.
Keywords Elevated CO₂ · Global change · Herbivory · Leaf chemistry · Vaccinium sp.
Contact Stephan Hättenschwiler: email | webpage
Research project The Swiss Canopy Crane Project (SCC)