Evaluation of Arthrobotrys flagrans concentration, predatory activity, and efficacy in a commercial product

Gastrointestinal nematodes pose a major threat to livestock health and productivity, and the growing inefficacy of commercial anthelmintics highlights the need for alternative control methods. This study evaluated BioVerm®, a Brazilian commercial product (BCP) based on the nematophagous fungus Arthrobotrys flagrans, using three criteria: chlamydospore count per gram (CCG), predatory activity, and efficacy in reducing infective larvae (L3). CCG was quantified using a Neubauer chamber. Predatory activity was assessed by inoculating Panagrellus spp. in Petri dishes. Efficacy was evaluated through coprocultures treated or not with (BCP), including post-gastrointestinal tract analysis using sheep feces. Three commercial batches were tested. The mean CCG ranged from 8333 to 12,500, significantly below the 5 × 10⁵ spores per gram stated on the label. Fungal growth was observed in only one batch, and high contamination was found in another. No significant reduction in L3 counts was detected in either in vitro or in vivo assays. These results indicate low fungal viability and support the urgent need for quality control measures to ensure BCP efficacy.