INTERACTIONS BETWEEN A MYCOPHAGOUS COLLEMBOLA, DRY YEAST AND THE EXTERNAL MYCELIUM OF AN ARBUSCULAR MYCORRHIZAL FUNGUS

A plant growth system with root-free hyphal compartments was used to e xamine the interactions between a mycophagous Collembola (Folsomia can dida Willem), dry yeast and an arbuscular mycorrhizal (AM) fungus [Glo mus caledonium (Nicol. & Gerd.) Trappe and Gerdemann] in terms of Coll embola reproduction, AM-hyphal length and AM-hyphal P transport. Colle mbola reproduction was unaffected by AM mycelium, but a supplement of dry yeast increased the Collembola population size. The addition of dr y yeast increased AM-hyphal P transport by increasing hyphal length. C ollembola without yeast affected neither AM-hyphal growth nor AM-hypha l P transport, whereas Collembola with yeast decreased AM-hyphal P tra nsport by 75% after a weeks. The hyphal density of G. caledonium remai ned unaffected by Collembola except after 4 weeks in combination with yeast, when a 33% reduction was observed. The results of this experime nt show that the interaction between F. candida and the external mycel ium of G. caledonium is limited under the conditions imposed.