Nematophagous fungi combinations reduce free-living stages of sheep gastrointestinal nematodes in the field

Gastrointestinal nematodes (GIN) can reduce or limit sheep production. Currently there is a clear deficiency in the action of drugs for the control of these parasites. Nematophagous fungi are natural enemies of GIN. Fungal combinations have potential for reducing GIN populations. The aim of this study was to evaluate the efficiency combinations of nematophagous fungi in sodium alginate matrix pellets for the biological control agents of gastrointestinal sheep nematode parasites in the field. The nematophagous fungi (0.2 mg of fungus per kg of body weight), Arthrobotrys conoides, A. robusta, Duddingtonia flagrans, and Monacrosporium thaumasium were used. The treated groups were administered mycelium combinations in the following combinations: group 1 (D. flagrans + A. robusta); group 2 (M. thaumasium + A. conoides). The control group did not receive any fungal pellets. We used three groups with eight Santa Inês sheep each. Each animal was treated with approximately 1 g of pellet per 10 kg of live weight. During the experimental period, we evaluated: number of eggs per gram of feces (EPG), infective larvae (L3) per kg of dry matter, larvae recovered from coprocultures, packed cell volume, total plasma protein concentration of sheep, and environmental conditions. Group 2 EPG (M. thaumasium + A. conoides) differed from the control group in September and October. The number of L3/kg of dry matter recovered from animals of groups 1 and 2 at distances of 0–20 and 20–40 cm from the fecal pats was lower than the control group. The packed cell volume and total plasma proteins of treated animals were similar to those of the control group. The combination of treatment groups (D. flagrans + A. robusta and M. thaumasium + A. conoides) reduced the number of L3/kg of pasture. Therefore, treatment of nematophagous fungal combinations have the potential to manage free-living stages of GIN in sheep