In vitro and in vivo studies of the native isolates of nematophagous fungi from China against the larvae of trichostrongylides

Abstract

To screen potential nematophagous fungi candidates for the biological control of parasitic nematodes in livestock, in vitro and in vivo studies of the native isolates of nematophagous fungi against the larvae of trichostrongylides were conducted. The in vitro predatory activity of 16 native nematophagous fungal isolates on the larvae of trichostrongylides in sheep feces was assessed. In the ten isolates of Duddingtonia flagrans, the reduction percentage for the infective larvae (L3) of Trichostrongylus colubriformis ranged from 57.21 to 99.83%, and that of Haemonchus contortus ranged from 62.12 to 99.88%. The analysis of the same assay on five isolates of Arthrobotrys superba and one isolate of A. cookedickinson (Monacrosporium cystosporum) showed comparable results with those for D. flagrans. To determine the excretion time of fungal isolates in feces after oral administration, D. flagrans (SDH035) were studied in vivo in sheep and rabbits. Results showed that the tested fungal isolates existed in sheep feces from 12 to 72 h after fungal treatment, and the fungal excretion in rabbit feces occurred at 4 h, reached a peak at 10 h, and declined gradually 18 h after oral administration. All the native fungal isolates were assessed after passing through the gastrointestinal tract of sheep. Treatment with isolates of D. flagrans significantly reduced the number of developing larvae in the feces, and the efficacies ranged from 55.15 to 98.82%. One out of the five isolates of A. superba and A. cookedickinson (BS002) survived after passing through the gastrointestinal tract, and the L3 reduction rates were 83.79 and 81.33%, respectively. Results of the present study provide information about the in vitro predatory activity of nematophagous fungi from China on the L3 of trichostrongylides and their ability to pass through the gastrointestinal tract before administering them for biocontrol.

In vitro assays on the susceptibility of four species of nematophagous fungi to anthelmintics and chemical fungicides/antifungal drug

“…(2017a) and Wang et al . (2017). The spore suspensions were adjusted to a concentration of 1 × 10 4 ml conidia for A .…”

“…Fungal spores were obtained in accordance with the methods of Cai et al (2017a) and Wang et al (2017). The spore suspensions were adjusted to a concentration of 1 × 10 4 ml conidia for A. oligospora, A. superba and Arthrobotrys sp.…”

“…Thus, the spores can be used as additive in feed to germinate and kill the larvae of parasitic nematodes in the dung pat of animals. Various formulations containing D. flagrans chlamydospores can effectively reduce the infective larvae in feces or pasture from sheep, goat, cattle and horses both in laboratory and field conditions (Braga and Araújo 2014;Wang et al 2017).…”

“…Various formulations containing D. flagrans chlamydospores can effectively reduce the infective larvae in feces or pasture from sheep, goat, cattle and horses both in laboratory and field conditions (Braga and Araújo 2014; Wang et al . 2017).…”

Individual and Combined Application of Nematophagous Fungi as Biological Control Agents against Gastrointestinal Nematodes in Domestic Animals

“…Its chlamydospores can withstand gastrointestinal transportation and other undesirable environments to germinate, forming as a predator device a three-dimensional network structure to capture living larvae in animal feces [37,40]. Experimental studies in vitro have shown that D. flagrans could reduce up to 96.4% of GINs, better than Monacrosporium thaumasium and Arthrobotrys robusta [41,42], and in in vivo tests a reduction of 55.15%-98.82% has been reported [43]. With the development of next-generation sequencing, genomic analysis of D. flagrans has shown that the species contains more abundant genes relating to the pathogenicity of nematodes than other fungi, such as cytochrome P450 genes and proteasecoding genes, which provide D. flagrans with stronger nematicidal activity and keep other enemies (such as fungal-feeding nematodes) from feeding [44,45].…”