A detailed view of the hyphae of Agaricus bisporus growing inside the grain. The 'foamy' background is the starchy endosperm. The presence of this heavily spore-forming microscopic fungus is visible as light blue to gray patches on the soil surface. This fung us usually feeds on trapped nematodes. A hypha and a newly formed spore of Arthrobotrys oligospora Spores of Arthrobotrys are usually pear-shaped and show a cross septum dividing the spore into two distinct areas.
Some nematodes feed on mycelium, hence the name myceliophagous nematodes.
Other nematodes feed on bacteria. Soil is a rich and diverse source of uni- and multicellular organisms in various stages of their life cycle which continuously compete for survival. The defense mechanisms of the cultivated mushroom's fruit bodies steadily become exhausted when they are attacked by mites, nematodes and pathogenic fungi like Trichoderma spp . Such severely parasitized mushrooms will eventually disintegrate. Arthrobotrys oligospora trapping a nematode.