Nematode-destroying fungi and theirs abilities to destroy free-living stages of gastrointestinal nematodes of livestock in laboratory

Study was a part of biological control of parasitic gastrointestinal nematode in livestock be nematode-destroying fungi project. The aims of these studies were to investigate and collect these fungi in faeces of livestock and soils as well as to determine efficiency of these fungi to destroy free-living stages of nematode under laboratory conditon. The first survey was implemented during October 1998 to March 1999 from 10 provinces. The second survey was done during September 1999 to May 2000 from 6 provinces in central, northeastern, southern part of Thailand. The total of ninty-nine faecal samples from grazing livestock, dairy, beef, buffaloes, horses, sheep goat and 15 soil samples were collected to determine for the presence of nematode-destroying fungi by faecal cultures on 2 percent water agar plate containing 0.02 percent chlotetracycline. In the first survey, one species of nematode endoparasitic fungus was found belonging to Harposporium anguillulae and 2 species of nematode-trapping fungi, Arthrobotrys oligospora and unidentified Arthrobotrys sp. In the second survey, 4 species of nematode endoparasitic fungi were found belonging to H. anguillulae, Meristacrum asterospermum, Catanaria anguillulae and unidentified endoparasitic nematode fungi in addition, 3 species of nematode-trapping were found belonging to A. oligospora, Dactylaria candida and unidentified nematode-trapping fungus. It was concluded that we found more 4 species of nematode-destroying fungi than those found in the first survey. One isolate of A. oligospora was selected to test whether the fungus can survive passage through the alimentary tract of a goat. In this experiment, A. oligospora successfully passed through the alimentary tract when it was single orally administration of 5*10**(5) conidia in water. Then, this fungus could be isolate in the goat faeces within 1-2 days after feeding. Moreover, the same isolate, A. oligospora was tested on germination of conidia and nematode-trapping ability by nets formation when several subculture was done and kept in 4-8 deg C for 8 months. It revealed that the conidia could be germinated but nets formation was not developed. In another experiment, H. anguillulae was carried out to test ability of destroying free-living stages of Trichostrongylids and Haemonchus contortus from sheep. The result showed that only the Trichostrongylid larvae were infected by H. anguillulae but not H. contortus larvae. The present studies was demonstrated that some local isolates of nematode-destroying fungi are potential to serve for biological control against free-living stages of parasitic gastrointestinal nematodes by feeding to host animals. Other laboratory experiments and field experiments will be carried out in next year.