Grasslands may contain 50 to 500 nematodes, and forest soils generally hold several hundred per teaspoon. Commonly, less disturbed soils contain more predatory nematodes, suggesting that predatory nematodes are highly sensitive to a wide range of disturbances. Several researchers have proposed approaches to assessing the status of soil quality by counting the number of nematodes in different families or trophic groups. Because they are quite small and live in water films, changes in nematode populations reflect changes in soil microenvironments. Blair, J. M. et al. 1996.
Soil invertebrates as indicators of soil quality.
In Methods for Assessing Soil Quality , SSSA Special Publication 49, pp. One group of fungi may be a useful biological control agent against parasitic nematodes. These predatory fungi grow through the soil, setting out traps when they detect signs of their prey. Some species use sticky traps, others make circular rings of hyphae to constrict their prey. When the trap is set, the fungi put out a lure, attracting nematodes that are looking for lunch.