Tn laboratory experiments survival, feeding and reproduction of nemato
des in cultures with mycorrhizal and saprophytic fungi were investigat
ed, Nematodes extracted from the organic layer of a spruce forest soil
were inoculated to fungal plates. The fungal feeder Aphelenchoides sa
prophilus was the most successful species to multiply With mycorrhizal
fungi as a food source its population developed faster and to a great
er extent than it did with saprophytic fungal species. The grazing of
A. saprophilus reduced mycelial weight and fungal growth rate. Similar
effects are likely to occur in the field, and can influence mycorrhiz
al development or affect competition between soil fungi. Besides A. sa
prophilus, the saprophagous nematode Acrobeloides nanus reproduced wel
l in cultures with mycorrhizal fungi. There may be an element of subst
rate ingestion or grazing on fungal hyphae for some bacterial feeding
nematodes.