# Predatory activity and nematocidal compounds released into liquid culture filtrates as attack strategies of a Mexican strain of Arthrobotrys oligospora against Haemonchus contortus infective larvae

## TL;DR

A Mexican strain of Arthrobotrys oligospora was found to effectively attack and kill Haemonchus contortus larvae using predatory activity and nematocidal compounds.

## Contribution

The study identifies a new strain of Arthrobotrys oligospora with high nematocidal activity and protease enzyme activity against parasitic nematode larvae.

## Key findings

- The isolated Arthrobotrys oligospora strain showed 72.06% predatory activity against Haemonchus contortus larvae.
- The liquid culture filtrate demonstrated 96.10% nematocidal activity at 100 mg/mL after 48 hours.
- The strain exhibited metalloprotease and cysteine-protease activities, which were higher under acidic conditions.

## Abstract

Nematophagous fungi offer a sustainable alternative for controlling nematode infections in small ruminants. The aims were to isolate and characterize both morphological and molecular nematophagous fungi from soil, to assess their predatory activity and the nematocidal activity of their liquid culture filtrates (LCF) against Haemonchus contortus infective larvae (L3), and to identify the protease activity of the LCF and mycoconstituents. The isolated and characterized Arthrobotrys oligospora was identified using both morphological and molecular techniques, with a similarity of 98%. Additionally, the isolated strain showed 89% phylogenetic similarity in the phylogenetic tree concerning the Arthrobotrys order. The A. oligospora isolate exhibited 72.06% predatory activity, and the liquid filtrate demonstrated 96.10% nematocidal activity at 100 mg/mL after 48 hours post-exposure against H. contortus infective larvae. Regarding enzyme activity, A. oligospora showed metalloprotease and cysteine-protease activities, and the zymogram revealed that these activities were higher under acidic conditions (pH 5).