DUNG-DERIVED BIOLOGICAL AGENTS ASSOCIATED WITH REDUCED NUMBERS OF INFECTIVE LARVAE OF EQUINE STRONGYLES IN FECAL CULTURES

Two sets of dung-derived organisms from soil routinely fertilized with manure (MA) and soil chemically fertilized (CH) were cultured separat ely in the laboratory. Baermannized organisms from these cultures were added to 20 g of faeces from strongyle-infected horses to form three treatment groups: (i) no soil organisms; (ii) low inoculum of soil org anisms containing all organisms present in a suspension of approximate ly 100 adult female free-living nematodes; and (iii) in high inoculum containing those soil organisms present with approximately 1000 adult female free-living nematodes. Three studies were conducted using MA cu ltures and faeces containing 50 strongyle epg, CH cultures and faeces containing 1500 strongyle epg, and a mixture of soil organisms from th e two cultures (MC) and faeces containing 600 strongyle epg. Within ea ch study, five control cultures and 15 each of low and high inoculum c ultures were prepared and incubated at 24 degrees C and 95% humidity i n a climate chamber for 15 days. Parasitic and free-living nematodes w ere then recovered by the Baermann technique and counted. The numbers of third stage larvae were significantly lower in the high inoculum gr oup compared to controls. The percent reductions in the number of thir d stage larvae for the low and high inoculum groups were 63.6% and 90. 9%, 85.1% and 97.1%, 84.5% and 98.4% for MA, CH, and MC studies, respe ctively, indicating that mortality increased with the number of soil o rganisms added to cultures. Examination of the source cultures detecte d the presence of two species of nematophagous fungi and three genera of free-living nematodes reported to be predacious.