Leaf miner activity and its effects on leaf chemistry in adult beech under elevated CO2

Using the Swiss Canopy Crane CO2 enrichment facility, the beech weevil's host choice in a CO2-enriched atmosphere and the in situ effect of its infestation on the chemistry of host leaves were investigated. The fraction of infested leaves was larger on CO2-enriched trees, suggesting that weevil impact on beech may increase as atmospheric CO2 concentration keeps rising. Egg insertion in the central leaf vein partially interrupts phloem and xylem transport. Because of this separation between the source of photosynthates, the leaf tip, and the rest of the plant, the leaf tip becomes enriched in non-structural carbohydrates and depleted in nitrogen. Elevated CO2 slightly enhanced nonstructural carbohydrates in uninfested leaves, but exerted no further increase in infested leaf part, suggesting a saturation effect. (C) 2010 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.