Density-dependent parasitism of the soil-borne nematodeCriconemella xenoplax by the nematophagous fungusHirsutella rhossiliensis.

Spatial sampling was used to investigate temporal density-dependent parasitism of the plant-parasitic nematodeCriconemella xenoplax byHirsutella rhossiliensis in three peach orchards on eight sample dates. The patches of soil in which the nematode and fungus interacted were assumed to possess similar density-dependent dynamics and to be small, independent, and asynchronous. Furthermore, sampling of separate patches was assumed to provide similar information with respect to density dependence as would temporal (repeated) sampling of the same patch. Percent parasitism was dependent on the number ofC. xenoplax/100 cm(3) soil (P=0.0001). The slope was unaffected by orchard or date but ranged from 0.0001 to 0.0043 depending on distance from the irrigation furrow. The relative shallowness of the slope and the large variation in percent parasitism not explained by nematode density suggest thatH. rhossiliensis is a weak regulator ofC. xenoplax population density.