[Comparison of the efficacy of different isolates of the nematode-trapping fungi Arthrobotrys spp. and Duddingtonia flagrans in reducing infective larvae of nematodes after passage through the digestive tract of sheep]. / Comparação da eficácia de diferentes isolados dos fungos nematófagos Arthrobotrys spp. e Duddingtonia flagrans na redução de larvas infectantes de nematóides após a passagem pelo trato digestivo de ovinos.

For oral application in ruminants, nematophagous fungi must has the capacity to survive the passage through the digestive tract and be efficient in reducing infective larvae of nematodes in the faeces. In this work, these capacities were evaluated and compared in Brazilians and Canadians isolates of Duddingtonia flagrans, Arthrobotrys musiformis and A. oligospora. Fungi were cultured in Rouxs Bottles with corn grain as a growth media, and a suspension of 700,000 chlamydospores (D. flagrans) or conidia (A. oligospora and A. musiformis) per Kg of body weight was administered orally for three consecutive days to a group of sheep naturally infected with gastrointestinal nematodes. The control group did not receive fungi. The faeces of these animals were colleted for 3 days pre and 3 days postadministration of the suspension and the number of eggs per gram of faeces (EPG) and fecal cultivations carried out. Infective larvae (L3) were recovered through baermanization, quantified and compared together with the EPG values. Only administration of D. flagrans significantly reduced the percentage of L3 in the fecal cultivations by more than 95%. These results indicate the potential of D. flagrans as a biological control agent for sheep nematodes.