1. Scottish Crop Research Institute; Invergowrie Dundee UK DD2 5DA
2. Institut Méditerranéen d'Ecologie et Paléoécologie, Université Saint Jérôme; FR-13397 Marseille cedex 20 France
3. School of Biological Sciences, University of Plymouth; Plymouth Devon UK PL4 8AA
4. Biomathematics and Statistics Scotland; Scottish Crop Research Institute; Invergowrie Dundee UK DD2 5DA
5. Soil Fauna and Ecotoxicology Research Unit, Department of Terrestrial Ecology; National Environmental Research Institute; P.O. Box 314, Vejlsoevej 25 DK-8600 Silkeborg Denmark