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Duddingtonia flagrans is highly host specific – targeting parasitic nematodes of grazing animals

Further studies

No follow up to the Roubaud and Deschiens study has been reported and it is assumed that the prospect of treating pasture areas with large quantities of fungus precluded continuation of this approach on economic and/or technical grounds.

Duddingtonia flagrans produces a thick walled chlamydospore which is resistant to gastrointestinal digestion and it survives passage through the gut of livestock species better than other species of nematophagous fungi (Larsen, 1991). Thus, a practical, convenient and cost-efficient method to apply the fungus to the control of nematode parasites has been developed – by adding the spores of the fungus to the feed. Following passage through the animal gut the fungus is applied on target in the faecal pat where it germinates into the nematophagous live stage and the nematodes are destroyed. In this way, re-infection of grazing animals is effectively reduced.

In the years since D. flagrans was confirmed to have the greatest potential for development as a biological control agent of nematode parasites of livestock (Peloille, 1991) a considerable amount of research has concentrated on this species.

Expectations of efficacy

In consideration of the efficacy expectations for products providing novel and non-chemical helminth control strategies, these products cannot be evaluated using the same criteria as chemical anthelmintics and Ketzis et al. (2006) proposed that evaluation be based on efficacy and economic benefit. After consideration of the published studies, the authors concluded that the use of D. flagrans met the proposed criteria.

In Australia, a field survey of nematophagous fungi by the Australian government science agency, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in 1992-1993 isolated a number of strains of Duddingtonia flagrans and from this collection the strain selected, IAH 1297, had the most suitable characteristics for scale-up and commercial production.