TY - Generic T1 - Effects of carbon dioxide and nitrogen enrichment on a plantinsect interaction: the quality of Calluna vulgaris as a host for Operophtera brumata Y1 - 1998 A1 - Kerslake, J.E. A1 - Woodin, S.J. A1 - Hartley, S.E. JF - New Phytologist VL - 140 ER -