Efficacy of Duddingtonia flagrans (Bioverm®) on the biological control of buffalo gastrointestinal nematodes.

We evaluated the efficacy of Bioverm®, a commercial product containing Duddingtonia flagrans, on the control of buffalo (Bubalus bubalis) gastrointestinal nematodes. We randomly divided 12 buffaloes into two groups of six animals. In the treated group, each animal received a Bioverm®`s single dose of 1g (105 chlamydospores of D. flagrans) to 10 kg of live weight; in the control group, each animal received 1g of corn bran for each 10 kg of live weight as a placebo. Fecal samples were individually collected from 12, 24, 36, 48, 60 and 72 h after treatments. To examine 1) viability of chlamydospores passed through the gastrointestinal tract, 2 g of faeces and 1000 infective larvae (L3) were added to Petri dishes with 2% water-agar, and 2) to examine larval predation by D. flagrans during fecal cultures, 2000 L3 were added. In the Petri dishes, were observed significant reductions (p < 0.01) in the treated group after 48 (56.7%) and 60 h (91.5%). In the fecal cultures, significant reductions (p < 0.01) occurred in the treated group from 36 h (75%), with larval reduction up to 72 h. High larval predation rate occurred 60 h after Bioverm® administration. Bioverm® maintained viability and predation capacity after passage through the buffalo's gastrointestinal tract, showing efficacy on gastrointestinal nematodes.

Viability of Strongyloides venezuelensis eggs and larvae in vermiculite containing the fungus Duddingtonia flagrans.

Strongyloidiasis is the most clinically important disease among the infections caused by geohelminths, seeing that this parasite can cause autoinfection. The use of nematophagous fungi like Duddingtonia flagrans, that have predation action on eggs and infecciososas forms of helminths, emerges as an alternative method for environmental control. For this reason, analyzing the viability of larvae and eggs of Strongyloides venezuelensis and the action of Duddingtonia flagrans AC001 in vermiculite, as well as the action of the nematophagous fungi in different growth stages, is important to elaborate and define the best culture conditions that favor the activity of the fungus. Two different growth conditions were applied: both eggs and AC001 fungi were added at the same time to the vermiculite (assay A) and the addition of eggs after the growth of the AC001 fungi in the vermiculite (assay B). To recover the L3 larvae, the Baermann-Moraes method was applied, followed by the counting of L3 dead and alive. At last, it was observed that the vermiculite enriched with organic material is an adequate culture medium not only for the growth of the S. venezuelensis but also for the growth of the D. flagrans fungus, being therefore, a satisfactory culture medium for tests of viability and predatory action of this fungus. It was also observed that the activity of the AC001 fungus is greater when it is growing concomitantly with the eggs, in other words, when it is in the adaptation phase.