Biological Control of Nematodes: Use of Nematophagous Fungi in Feces to Control Gastrointestinal Nematodes

For further information, contact National Institute of Animal Health, Department of Livestock Development, Ministry of Agriculture and Cooperatives, Chatuchak, Bangkok, Thailand., 2003-09-01

Ability of Fungus to Control Gastriointestinal Nematodes

This study evaluated the ability of a nematophagous fungus to destroy free-living nematodes in fecal samples and produce its chlamydospores in large scale. One local isolate of nematophagous fungus, Arthrobotrys oligospora, obtained from soil samples was used in this study.

Germination after Conidia Have Passed through Digestive Tract of Animals

Germination of conidia or chlamydospores and three-dimensional adhesive net formation for trapping free-living nematodes were observed in vitro. These were done to test the resistance of conidia or chlamydospores after they have passed through the alimentary tracts of animals. Four 1.5-month-old male dairy calves were used in experiment 1. Conidia of A. oligospora were individually administered orally to the calves at a variable dosage of 1 x 106-4 x 106 conidia per kilogram body weight per calf. Germination and three-dimensional nets were observed in fecal samples within 2 days after the experiment. Free-living stage of bovine gastrointestinal nematodes trapped by the nets was observed in day 5 of the experiment. Four BAL/C mice were used in experiment 2. Individually, the mice were orally administered with chlamydospores of A. oligospora which had been kept in water for 1 year. Germination and three-dimensional nets were also observed in fecal samples within 2 days after the experiment. Free living rhabditoid nematodes trapped by the nets were seen within 2-3 weeks of the experiment.

Mass Production of Chlamydospores

Mass production of chlamydospores was successful in this study. The best medium for hyphal growth of A. oligospora was potato dextrose broth (PDB). The chlamydospores were achieved after replacement of PDB with water in the same flask. The results indicate that a local isolate of A. oligospora has the potential as a biological control of free-living bovine gastrointestinal nematodes by oral administration of conidia.

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