1. Forest Research, Alice Holt Lodge, Farnham, Surrey GU10 4LH, England
2. Department of Forest Protection, Austrian Research Centre for Forests (BFW), Seckendorff-Gudent-Weg 8, 1131 Vienna, Austria
3. National Reference Centre, Netherlands Food and Consumer Product Safety Authority (NVWA), Ministry of Agriculture, Nature and Food Quality, Geertjesweg 15, 6706 EA, Wageningen, The Netherlands
4. Forest Research, Northern Research Station, Roslin, Midlothian EH25 9SY, Scotland