Nematophagous Activity of Duddingtonia Flagrans MUCL 9827 Against Sheep Gastrointestinal Nematodes

Gastro-intestinal nematodes (GIN) of sheep are one of major constraints in grazing production systems worldwide. Control is commonly achieved using anthelmintics, but global occurrence of anthelmintic resistance to different drugs and the emergence of multi-resistant GIN species seriously limit the efficiency of their use. Therefore, integrated parasite management is widely recommended, with nematophagous fungi as one of control tools. Duddingtonia flagrans is one of the most used species, with various effect of different isolates. In previously performed coproculture assay, we showed low efficacy of D. flagrans MUCL 9827 against infective larvae (L3) of sheep GIN. The aim of current experiment was to reevaluate its nematophagous potential, using the medium where direct interaction between the fungus and L3 could be observed. Nematophagous activity was tested on 2% water agar with addition of chloramphenicol on three series of plates seeded with 500 and 1000 chlamidospores and agar blocks with 7 days old mycelium. At Days 0 and 5, 500 L3 of sheep GIN were added to test the trapping activity. The cultures, including control plates with only L3, were incubated at 25°C for 10 days, followed by evaluation of their number and reduction percentage. Nematophagous activity of D. flagrans MUCL 9827 against L3 was clearly demonstrated. However, the overall efficacy was poor since trapping was observed only in one out of nine plates containing fungal material. Potential reasons for such poor performance of the isolate of fungal species, otherwise known as successful in trapping animal parasitic nematodes, are discussed.