THE POTENTIAL OF NEMATOPHAGOUS FUNGI TO CONTROL THE FREE-LIVING STAGES OF NEMATODE PARASITES OF SHEEP - IN-VITRO AND IN-VIVO STUDIES

Following in vitro screening investigations on approximately 100 nemat ophagous fungi reported previously, eight species were selected for fu rther investigation. Fungal elements (mycelium and conidia) were subje cted to in vitro stress selection designed to simulate rumen and aboma sal conditions. From these studies, three species, namely, Arthrobotry s oligospora, Arthrobotrys oviformis and Geniculifera eudermata, were selected for in vivo survival studies in sheep surgically fitted with abomasal and ileal cannulae. Doses of fungal conidia were administered orally or via the abomasal cannulae and samples of digesta were taken from the abomasum, the terminal ileum and faeces. The viability of th e three fungal species at these sites was demonstrated. The abundance of fungi throughout the gut was dose-dependent but in all cases only v ery small volumes of fungal suspension containing unprotected conidia were used. These results demonstrate that a practical means of orally administering nematophagous fungi to control free-living stages of nem atodes in faeces may become an achievable objective.