The potential of nematophagous fungi to control the free-living stages of nematode parasites of sheep: screening studies.

Ninety-four species of fungi with known nematophagous activity were tested for their ability to reduce the number of infective larvae of sheep nematodes in faecal cultures, and also for their ability to produce nematode-attractant and nematocidal substances against these free-living stages under in vitro conditions. Reductions of infective larval numbers exceeding 80% were consistently recorded when 100-250 conidia g-1 faeces of various species from the genera Arthrobotrys, Geniculifera and Monacrosporium were used. Even concentrations as low as 10 conidia g-1 faeces resulted in a significant reduction in infective larval numbers compared to control cultures. This study demonstrates that whilst many fungal species exhibit nematophagous activity against a variety of free-living nematodes, few show efficient activity against the free-living stages of parasitic nematodes in the sheep faecal environment. For the most active, there were six species of Arthrobotrys, two species of Geniculifera and two species of Monacrosporium which showed comparable activity to the extensively studied species A. oligospora.