Studies on the Relationships Between Nematodes and Other Soil Microorganisms:i. The Influence of Actinomycetes and Fungi on Rhabditis (Cephaloboides) Oxycerca De Man

The influence of actinomycetes and fungi isolated from soil and from plant roots on Rhabditis (Cephaloboides) oxycerca de Man, a bacteria-feeding nematode, was studied. A striking accumulation of nematodes occurred in the vicinity of colonies of certain species of these organisms growing on agar media. There was little evidence of repulsion of the nematodes. Shake-culture filtrates of a large percentage of the actinomycetes tested strongly attracted the worms and none repelled or was toxic to them. It is suggested that the commonly observed attraction of nematodes to plant roots may be due not only to root diffusates but also to the abundance and activity of the soil microorganisms in the vicinity of the roots.