The potential of nematophagous fungi to control the free-living stages of nematode parasites of sheep: comparison between Australian isolates of Arthrobotrys spp. and Duddingtonia flagrans.

Nine isolates of Duddingtonia flagrans and eight isolates of Arthrobotrys spp. which originated from a field survey for the presence of nematophagous fungi in fresh dung of livestock in Australia were used in this study. Comparisons were made between the ability of the different isolates to survive gut passage and subsequently reduce infective larval numbers in sheep faeces. Fungal spores (conidia and/or chlamydospores) were administered orally to sheep in doses ranging from 1 X 10(5) to 4.5 X 10(6) spores. There was no apparent consistent survival of Arthrobotrys spp., whereas D. flagrans showed excellent survival capacity which resulted in profound reductions in Trichostrongylus colubriformis larval numbers in culture. This provides clear evidence that D. flagrans is an ideal candidate as a potential biological control agent for nematode parasites of sheep.