EN
Duddingtonia flagransis a nematode trapping fungus used for the control of gastrointestinal nematodesin livestock. The quantity of chlamydospores of D. flagransrequired for the reduction of third-stage larvae (L3) of sheepgastrointestinal nematodes (GIN) is largely unknown, and a matter of discussion. The aim of this experiment was todetermine in vitrothe nematophagous activity of four different concentrations ofD. flagrans(1000, 3000, 6250, or11000 chlamydospores/ml) in the presence of varying numbers of GIN third-stage larvae (L3) (500, 1000, 1500).Additionally, the study sought to evaluate the efficacy of this fungus on Haemonchus contortus,Teladorsagiacircumcincta,Trichostrongylus colubriformisand Chabertia ovina. The results showed that as fungal concentrationsincreased, so did the larval reduction of third-stage infective larvae in each test. L3s number was not a determiningfactor in the efficacy against GIN. The comparison between various concentrations of chlamydospores revealedsignificant differences, particularly between 1000 and 11000 chlamydospores (P≤0.05). Regarding the larval reductionof the GIN species considered, D. flagransdemonstrated the same effectiveness across all species tested. The results ofthe current study confirm the efficacy and underscore the importance of D. flagransas an alternative for controlling ofGIN.