A pilot study of the in vitro efficacy of different concentrations of Duddingtonia flagrans for the control of gastrointestinal nematodes of sheep.

Duddingtonia flagrans is a nematode trapping fungus used for the control of gastrointestinal nematodes in livestock. The quantity of chlamydospores of D. flagrans required for the reduction of third-stage larvae (L3) of sheep gastrointestinal nematodes (GIN) is largely unknown, and a matter of discussion. The aim of this experiment was to determine in vitro the nematophagous activity of four different concentrations of D. flagrans (1000, 3000, 6250, or 11000 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, Teladorsagia circumcincta, Trichostrongylus colubriformis and Chabertia ovina. The results showed that as fungal concentrations increased, so did the larval reduction of third-stage infective larvae in each test. L3s number was not a determining factor in the efficacy against GIN. The comparison between various concentrations of chlamydospores revealed significant differences, particularly between 1000 and 11000 chlamydospores (P≤0.05). Regarding the larval reduction of the GIN species considered, D. flagrans demonstrated the same effectiveness across all species tested. The results of the current study confirm the efficacy and underscore the importance of D. flagrans as an alternative for controlling of GIN.