NEMATOPHAGOUS FUNGI FOR THE CONTROL OF EQUINE CYATHOSTOMES

Cyathostomes have emerged as the major endoparasites in horses in the United States. Problems associated with the control of cyathostomes in clude drug resistance, failure of anthelmintics to kill encysted and h ypobiotic larvae, and the potential ecotoxicity of widespread use of i vermectin. An alternative method of parasite control involves the use of nematophagous fungi to infect and consume nematodes on pasture. Nem atophagous fungi occur in a wide variety of taxonomic groups, in which the ability to ingest and destroy nematodes has independently evolved . The fungi are generally categorized into the following three functio nal classes: egg-attacking fungi, endoparasitic fungi, and predaceous fungi. Most research has focused on food animal parasites; there has b een scant study of equine parasites. The cyathostomes are an excellent subject for further research because of the associated control proble ms. Early reports indicated that feeding fungi are apparently safe for equids and that pastures are unaffected by the presence of high level s of predaceous fungi. This article describes this diverse group of fu ngi as well as studies that investigate the potential use of the fungi in controlling cyathostomes.