Arthrobotrys thaumasia and A. musiformis (Fungi: Orbiliales) as Natural Potential Enemies of Haemonchus contortus (Nematoda: Trichostrongylidae)

Haemonchus contortus (Hc) is a parasitic nematode affecting sheep. Arthrobotrys is a group of nematophagous fungi (NF) that capture nematodes with specialized traps. This study evaluated the in vitro predatory ability of Arthrobotrys thaumasia (At) and A. musiformis (Am), as well as the nematocidal activity of their liquid culture filtrates against Hc. NF isolates were obtained by sprinkling soil onto agar plates containing nematodes. Isolates were identified morphologically and molecularly. The predatory activity (PA) was tested on agar plates inoculated with nematodes and fungi; plates inoculated only with nematodes served as controls. After 10 days at 18 °C and 28 °C, larvae were counted. For nematocidal activity (NA) of LCFs, fungi were grown in Czapek–Dox (CzDB) and potato dextrose broths. Two concentrations (100 mg/mL and 130 mg/mL) were tested. Nematodes and LCFs were incubated for 48 or 72 h. PA was analyzed using unpaired Student’s t-tests, and LCFs were evaluated by ANOVA with Tukey’s post hoc test. Taxonomic procedures confirmed the isolates as Am and At. For PA, effectiveness was 74.64% for Am and 83.53% for At. The highest NA of LCF of Am in CzDB was 51% at 100 mg/mL and 76.7% at 130 mg/mL. That of the LCF of At was 22% at the highest concentration. Both isolates show strong potential as biocontrol agents against haemonchosis.