Rhabditis spp., in the Espírito Santo, State of Brazil and evaluation of biological control

Abstract

The objectives of this study were to describe occurrences of Rhabditis spp. causing parasitic otitis in dairy cattle of Gir breed in the state of Espírito Santo, southeastern Brazil, and to evaluate the biological control of this nematode using the nematophagous fungi Duddingtonia flagrans (AC001) and Monacrosporium thaumasium (NF34). After nematode detection and collection, three groups were formed: two groups that were treated, respectively, with the fungal isolates; and a control group, without fungus. The treatments were as follows: (a) Petri dishes containing the culture medium 2% water agar (WA) + 250 nematodes + AC001; (b) Petri dishes containing 2% WA + 250 nematodes + NF34; and (c) Petri dishes containing only 2% WA + 250 nematodes. After seven days at 27 °C the treatments with fungi were able to capture and destroy the nematodes, with percentages of 82.0% (AC001) and 39.0% (NF34) in relation to the control group. The results demonstrate the occurrence of Rhabditis spp. after animals physical examination and that there was efficacy of the in vitro predatory activity of both fungal isolates. Thus, these results are important because they can assist in future in vivo control of this nematode in cattle.