Assessment of the efficacy in vitro of Duddingtonia flagrans isolate 03/99 in different doses of chlamydospores and faeces egg counts in faecal of sheep

Abstract

The oral application of chlamydospores of the nematophagous fungus Duddingtonia flagrans allows reducing the number of infective larvae (L3) in faeces and decreases the infectivity of the pastures of gastrointestinal nematodes. There are differences in the literature about the quantity of chlamydospores required for the reduction of L3 and there is little data about the importance of the concentration of parasite eggs in faeces in relation to the predatory effect of fungus. This study evaluated the reduction of L3 in faeces taking into account four concentrations of chlamydospores of D. flagrans with four concentrations of faecal eggs per gram (epg). Two hundred coprocultures were performed with 10 g each one, using faeces from four parasitised sheep with natural infections. The coprocultures were distributed in treated groups (GT) containing 180, 620, 1460 and 3600 epg along with 1000, 6250, 3000 and 11,000 chlamydospores per gram of faeces. Four control groups without chlamydospores were performed for each GT. The coprocultures were incubated for 16 days at room temperature of 27°C. The reduction percentages for the group of 11,000 chlamydospores and epg 180, 620, 1460 and 3600 were 6.51%; 1.35%; 52% and 85%, respectively. In the group of 6250 chlamydospores the reduction percentages for epg 180, 620, 1460 and 3600 were 16%; 20%; 66% and 67%, respectively. These results would indicate that the predatory capacity of D. flagrans can be dependent on the stimulus generated by the presence of larvae as well as the concentration of chlamydospores present in the faeces.