1. Evolution, Ecology and Genetics Division; Research School of Biology; The Australian National University; Canberra ACT 2601 Australia
2. Laboratory of Entomology; Wageningen University; PO Box 16 6700 AA Wageningen The Netherlands
3. Department of Biochemistry; Max Planck Institute for Chemical Ecology; Hans-Knöll-Str. 8 D-07745 Jena Germany