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.
The objective of this study was to evaluate, in vitro, the colonization and destruction of ants of the genus sp. by the ovicidal fungus (VC4 isolate), in the southeast region of Brazil. The insects used in the experiment were worker ants of the genus sp., collected periodically in the environment and immediately transported to the laboratory in test tubes. Then, VC4 growth was promoted in 2% chitin agar medium (2% WQ) to obtain a fungal solution containing conidia and/or chlamydospores. Two experimental groups were formed. Treated group consisted of Petri dishes containing 2% agar-water culture medium (2% WA) with nine live insects and 20 µL of fungal solution at the concentration of 15,000 conidia/chlamydospores. Control group consisted of Petri dishes containing 2% WA culture medium and nine live insects. The dishes in the treated and control groups were incubated in BOD at 25 ± 1 °C and 80 ± 10% relative humidity for 4 days. After 4 days, it was observed that the VC4 had grown, colonized, and caused the destruction of the ants. The fungus was efficient at colonizing and destroying the urban ants collected on an experimental basis. Thus, it could open up new ways to reduce the use of chemical compounds in the future, decreasing health and environmental problems.
A B S T R A C TFecal environment in conjunction with the pastures act as a sort of "incubator" and reservoir propagator for infective larvae (L3) belonging to nematode parasites. In this sense, the use of antagonists that can act to control the development of nematodes in stool is welcome. In the present the nematophagous fungus Duddingtonia flagrans (AC001) was used. The objective of this study was to use the fungus Duddingtonia flagrans in the biological control of the development of nematode larvae in equine stool. Feces from parasited equine raised on pasture in a rural property in the south east region of Espirito Santo -Brazil were used during the months of July to August 2015. Then, the fecal samples were separated into two equidistant locations where they were divided into a control group and a group treated with fungus. Weekly, in the treated group, 2 mL of the fungus with an approximate concentration of 1,000 chlamydospores was added. In the control group 2 mL of distilled water was added. Next, from each stool sample, in each group, total fecal masses were collected for further analysis of EPG, stool cultures, and later the Baermann for L3 reduction analysis. The dynamics of the experiment was based on the addition of fungus and or distilled water, collection of total fecal mass, followed by replacement of the fecal boli from the treated and control groups with positive stool for equine gastrointestinal nematodes. The results demonstrated that the larvae mean counts for the control group were higher than the average L3 retrieved from the group treated with AC001 (p<0.01). The L3 reduction percentage retrieved from the group treated with AC001 was 48.2% in relation to the control group. The results of this study point to the need for further research to be carried out involving the biological control for nematode population dynamics in equine stool.
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