In: Lebrun, P., Andre, H.M., De Medts, A., Gregoire-Wibo, C., Wauthy, G. (eds.). New trends in soil biology. Proceedings of the VIII International Colloquium of Soil Zoology, Louvain-la-Neuve, 1982: International Colloquium of Soil Zoology, 8th, 1982, Louvain-le-Neuve, Universite Catholique de Louvain, 427-431.