Predacious activity of Duddingtonia flagrans within the cattle faecal pat

Abstract

Two studies were conducted to investigate the growth and activity of the fungus, Duddingtonia flagrans, within cattle faecal pats. Artificial faecal pats were constructed with the centre separated from the outer layer by a nylon mesh. Eight treatments were tested, by varying the presence/absence of Cooperia oncophora eggs and fungal spores within each layer. With parasite eggs in the centre layer, a statistically lower recovery of larvae was observed compared to both pats with parasite eggs in the periphery and pats with parasite eggs throughout both layers. Regardless of location within the pat, if co-located with the parasite egg, D. flagrans was found to be effective in trapping developing larvae. The reduction in recovery of larvae from pats with parasite eggs and fungal spores in the centre was found to be significantly higher than when parasite eggs were in the centre and fungal spores in the periphery. In the second study, pats were made up in two treatments: pats containing fungal spores and C. oncophora eggs (fungus) and pats containing C. oncophora eggs (control). The pats were incubated at low or high humidity. Ten pats were used in a cross over where five pats incubated at low humidity for 7 weeks were removed, water added and then incubated at a high humidity for 1 week. Another five pats were incubated at a high humidity for 7 weeks, aerated and incubated at a low humidity for 1 week. There was no apparent growth of fungus in faecal pats incubated at a high humidity and less than 20% of larvae were recovered. The growth of D. flagrans was observed in faecal pats incubated at a low humidity, but a corresponding reduction in the percentage recovery of larvae did not occur, except in week 4. No statistical difference between fungal and control pats was seen in the change over pats. Nematophagous activity was assessed throughout the study and observed in the first 4 weeks within the pats containing fungus.

Digestibility of Duddingtonia flagrans chlamydospores in ruminants: in vitro and in vivo studies

“…However, it is important to point out that both viability and recovery of chlamydospores in the faeces need to be considered for effective usage of D. flagrans . Faedo et al [8] and Grønvold et al [9] suggested a significant loss (not measured) of orally administered chlamydospores as a result of the passage through the GIT (digestion). Their suggestions were not confirmed in quantitative terms.…”

“…The present result matches the values suggested by Grønvold et al [9] where they speculated that more than 90% of dosed chlamydospores were lost in the GIT. Similarly, Grønvold et al [5] and Faedo et al [8] suggested a high loss of chlamydospores but no quantitative assessment was made. Under the conditions of diet and animals of the present trial, the amount of chlamydospores reaching the faeces was around 10% irrespective of the dose used.…”

“…This was first suspected using in vitro digestion studies with an in vitro incubation process simulating rumen+abomasum conditions that resulted in a significant loss of the chlamydospore viability [2]. Other workers suggested the existence of significant losses of the total chlamydospore number, without any quantitative evidence of this claim [8,9]. The capacity of chlamydospores to bypass the ruminant digestion process has been based on in vitro observations using qualitative assessments of chlamydospore resistance (presence or absence of fungal specific features).…”

Biotic interactions in soil and dung shape parasite transmission in temperate ruminant systems: An integrative framework

“…Increased stochastic variation in temperature (García‐Carreras & Reuman, 2013) has been shown to increase nematode‐trapping efficacy for D. flagrans compared to constant temperatures (Fernández et al, 1999) and alters nematode species preferences by fungi (Paraud et al, 2006), consistent across a changing climate. Humidity favors fungal survival, but nematode trapping increases in dry conditions (Faedo et al, 2002; Liu et al, 2009). High rainfall could also drive the breakup of dung and passive dispersal of parasite larvae from dung, reducing local larval abundance and, hence, the action of nematophagous fungi whose trapping activity is triggered by parasitic larval abundance (Buske et al, 2013).…”