Effects of elevated CO_2 and temperature on the leaf chemistry of birch Betula pendula (Roth) and the feeding behaviour of the weevil Phyllobius maculicornis

摘要

The effect of elevated CO_2 and temperature on the foliar chemistry Betula pendula Roth and the feeding performance of polyphagous weevils Phyllobius maculicornis Germ, was studied. Birch seedlings were grown during one growing season in chamber-less field conditions and in closed-top chambers exposed to four different treatments: ambient CO_2 (350 p.p.m) and temperature, elevated atmospheric CO_2 (700 p.p.m) and ambient temperature, elevated temperature +3 deg C above ambient) and ambient CO_2, and a combination of elevated CO_2 and temperature. In leaves under CO_2 enrichment, the concentration of nitrogen and some flavonol glycosides significantly decreased, whereas the concentration of total phenolics, condensed tannins and (+)-catechin significantly increased. The total concentration of cinnamoylquinic acids was significantly increased by CO_2 and decreased by temperature. The concentration of salidroside increased under elevated temperature. Weevil-feeding experiments were carried out in afive-choice arrangement, one leaf from each of the five treatments (chamber-less field controls and four different treatments in chambers) being placed in random order in a plastic box. The weevils preferred the leaves grown under elevated CO_2, which had low nitrogen, high phenolics and the highest condensed tannin concentrations. Whether the reason for this trend is due to the stimulating effect of condensed tannins and/or a change in other secondary compounds, remains unknown. The weevils did not show any obviously different response in feeding performance to temperature and the combination of elevated CO_2 and temperature.