RESUMO

This study aimed to evaluate the concomitant use of the nematophagous fungus Duddingtonia flagrans (AC001) and its protease-rich crude extract for the in vitro control of Panagrellus sp., Haemonchus spp., and Trichostrongylus spp. The nematicidal tests were carried out on larvae of the free-living nematode Panagrellus sp. and infective larvae of the gastrointestinal parasitic nematodes of domestic ruminants (Haemonchus spp. and Trichostrongylus spp). Five experimental groups were set: (1) one control group (G1) and (4) four treated groups -G2 - active crude extract; G3 - denatured crude extract; G4 - fungus, and G5 - fungus + active extract. Plates were incubated at 28 ºC for 24 h followed by the recovery of the larvae using the Baermann technique. The results showed a lower recovery of Panagrellus sp. larvae in the experimental groups compared to the control group, as follows: 52 % (G2), 16 % (G3), 46 % (G4), and 77 % (G5). An even greater reduction (77 ± 5 %) occurred in the group (G5). In addition, the authors observed lower averages of L3 of Haemonchus spp. and Trichostrongylus spp. in the experimental groups compared to the control group, as follows: 59 % (G2), 0 % (G3), 86 % (G4), and 76 % (G5). In turn, there was a difference (p < 0.01) between (G5) and (G2). The results this study indicate a positive effect from the compatible use of the D. flagrans fungus and its enzymatic crude extract (protease), which has been demonstrated here for the first time and with potential field applications for further designs.

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RESUMO

The purpose of using nematophagous fungi as biological control agents of gastrointestinal nematodes of livestock is to reduce the build-up of infective larvae on pasture and thus avoid clinical and subclinical disease. As the interaction of fungus-larval stages takes place in the environment, it is crucial to know how useful the fungal agents are throughout the seasons in areas where livestock graze all year-round. This study was designed to determine the predatory ability of the nematophagous fungus Duddingtonia flagrans against gastrointestinal nematodes of cattle during four experiments set up in different seasons. In each experiment, faeces containing eggs of gastrointestinal nematodes were mixed with 11,000 chlamydospores/g and deposited on pasture plots. A comparison between fungal-added faeces and control faeces without fungus were made with regard to pasture infectivity, larval presence in faecal pats, faecal cultures, faecal pat weight, and temperature inside the faecal mass. In three of the four experiments, Duddingtonia flagrans significantly reduced the population of infective larvae in cultures (68 to 97%), on herbage (80 to 100%), and inside the faecal pats (70 to 95%). The study demonstrated the possibility of counting on a biological control tool throughout most of the year in cattle regions with extensive grazing seasons.

RESUMO

Cooperia, Haemonchus and Oesophagostomum are the genera of gastrointestinal parasitic nematodes most prevalent in cattle and constitute a serious problem in cattle breeding due to the impact they have on meat and milk production and the high costs of control measures. The objective of the present work was to evaluate the efficiency of Bioverm® (Duddingtonia flagrans) in the control of gastrointestinal parasitism of young cattle raised in the field, in the Central-West region of Brazil. The experiment was conducted on a farm located in the municipality of Jangada, MT, where 18 cattle, Nelore and Aberdeen Angus breeds, aged six to ten months, were randomly divided into two groups (treated group and control group) and distributed in paddocks of Brachiaria decumbens, naturally infested by larvae of gastrointestinal nematodes. The animals in the treated group received 1g of Bioverm® for each 10 kg of body weight, administered daily with commercial feed, throughout a period of six months. In the control group, each animal received 1 g of rice bran for each 10 kg of body weight, without Bioverm®, added to the feed. Stool and pasture samples were collected every two weeks. The treated group showed a significant reduction (p < 0.05) in values of eggs per gram of feces (EPG) and a significant gain of body weight (p < 0.05) when compared to the control group. The fungal formulation Bioverm® was effective in pasture decontamination and consequently in reducing the occurrence of reinfection by nematodes. The animals treated with Bioverm® showed a lower parasitic load and greater weight gain.

RESUMO

Variations in temperature can affect the development of nematophagous fungi, especially when they are used in the biological control of parasitic nematodes in the pastures where cattle are reared. The aim of this work was to evaluate the effects of temperature on the performance of nematophagous fungi in the biological control of bovine parasitic nematodes. The mycelial growth, chlamydospore production and nematicidal activity of Duddingtonia flagrans, Arthrobotrys cladodes and Pochonia chlamydosporia were evaluated at 15, 20, 25, 30 and 35°C. The fungal strains achieved mycelial growth, chlamydospore production and nematicidal activity on parasitic nematodes under all temperature conditions tested. The fungi showed higher growth at intermediate temperatures (20, 25 and 30°C) than at the extremes of 15 and 35°C. At 25 and 30°C, D. flagrans realized 96.8 and 94.5% nematicidal activity on bovine parasitic nematodes, respectively. Arthrobotrys cladodes effected nematicidal activity of 85.3 and 83.5%, at 20 and 25°C, respectively. At 20 and 30°C, P. chlamydosporia achieved nematicidal activity of 81.3 and 87.4%, respectively. The maximum chlamydospore production was reached at 20, 25 and 30°C for D. flagrans, at 20 and 25°C for A. cladodes and P. chlamydosporia. The results of this study demonstrated that the tested fungal strains of D. flagrans, A. cladodes and P. chlamydosporia, when used in the biological control of bovine parasitic nematodes, were not limited by in vitro temperature variations. Therefore, the use of these strains of fungi as biological control agents of parasitic nematodes is promising.

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RESUMO

The objective of the present work was to evaluate the efficiency of Bioverm® fungal formulation (Duddingtonia flagrans-AC001) in controlling Haemonchus contortus and Strongyloides papillosus in sheep. In vitro predation tests were carried out in Petri dishes containing agar culture medium 2%. Four experimental groups were formed, with five replicates each: Group 1: 1 g of Bioverm ® and 1000 third-stage larvae (L3) of H. contortus; Group 2: 1000 L3 of H. contortus; Group 3: 1 g of Bioverm ® and 1000 L3 of S. papillosus; and Group 4: 1000 L3 of S. papillosus. In the in vivo tests, twelve 11-month-old sheep males positive for H. contortus were used. The animals were sorted in two groups (treatment and control), based on fecal egg counts (eggs per gram, EPG). Each group comprised six animals: treatment group-each animal received orally 100 g of Bioverm ® ; and control group-each animal received orally 100 g of rice. Subsequently, feces from these animals were collected at 12, 24, 36, 48, 60, 72, 84, and 96 h after Bioverm ® administration. In vitro results demonstrate that D. flagrans kept its predatory activity with 91.5% of mean reduction percentage of L3. After the passage test, Bioverm ® presented efficacy already after 12 h of its administration and kept similar results for 60 h. Bioverm® fungal formulation (D. flagrans-AC001) was efficient in reducing the population of H. contortus and S. papillosus under laboratory conditions in sheep feces. However, further studies are needed under natural conditions of ruminant grazing to prove the efficiency of this product.

RESUMO

We describe the synthesis and a function of melanin in Duddingtonia flagrans, a nematode-trapping fungus. We tested various culture media treated with L-DOPA, glucose and tricyclazole on fungal growth and melanin distribution using infrared spectroscopy (IS), electron paramagnetic resonance (EPR) and transmission electron microscopy (TEM). In vitro rumen digestion was used to test the environmental stress and then to evaluate the capacity of this fungus to trap nematode larvae. The growth and melanization of the fungus after 21 days of incubation at 30°C were best in Sabouraud dextrose medium. IS indicated the presence of melanin in D. flagrans, with similar bands for commercial melanin used as a control, and assigned the values obtained by EPR (g of 2.0051 ± 0.0001) to the production of melanin by the fungus. TEM indicated that melanin was produced in melanosomes but was not totally inhibited by tricyclazole. Within the limits of experimental error, the predatory activity of fungus treated with tricyclazole was drastically affected after 27 h of in vitro anaerobic stress with rumen inoculum. The deposition of melanin particles on the fungal cell wall contributed to the maintenance of D. flagrans predatory abilities after in vitro anaerobic ruminal stress.

RESUMO

Duddingtonia flagrans has been tested as an alternative parasite control, but data from in vitro experiments based on in vivo calculations describing nematophagous fungi predation in nematodes are restricted. The objective of this work was to determine the efficacy of D. flagrans against sheep nematode larvae in vitro using in vivo calculations. Fecal samples were introduced to fungi in different concentrations: 0.0/control; 0.05; 0.1; 0.2; 0.4; 0.8; 1.6; 3.2; and 6.4 g corresponding, respectively, to 583.000; 1.166.000; 2.332.000; 4.664.000; 9.328.000; 18.656.000; 37.312.000 and 74.624.000 chlamydospores/kg of body weight. The material was incubated for 14 days, before the larvae recovery (Assay 1). Assay 2 was carried out with the doses of 0.00625; 0.0125; and 0.025 g. The results showed a negative correlation between fungal concentrations and larval numbers for both assays. The fungus demonstrated an efficacy above 89% in both assays. Thus, we consider that the data from in vitro studies based on in vivo calculations may optimize the fungi quantities for field experiments.(AU)

Duddingtonia flagrans tem sido testado como uma alternativa no controle de parasitos, entretanto, trabalhos in vitro da predação de nematoides por fungos nematófagos correlacionados com cálculos baseados para testes in vivo são restritos. O objetivo deste trabalho foi determinar a eficácia in vitro de D. flagrans contra larvas de nematoides de ovinos tendo como base cálculos in vivo. Amostras fecais receberam a adição do fungo em diferentes concentrações: 0.0/controle; 0,05; 0,1; 0,2; 0,4; 0,8; 1,6; 3,2 e 6,4 gramas correspondendo, respectivamente, às seguintes dosagens: 583.000; 1.166.000; 2.332.000; 4.664.000; 9.328.000; 18.656.000; 37.312.000 e 74.624.000 clamidósporos/Kg de peso vivo animal. O material foi incubado por 14 dias, para recuperação das larvas (Ensaio 1). O Ensaio 2 foi realizado com concentrações de 0,00625; 0,0125 e 0,025 g. Foi observada correlação negativa entre a concentração fúngica e o número de larvas, nos dois ensaios. O fungo demonstrou eficácia acima de 89% em ambos os ensaios. A partir destes dados, acreditamos que ensaios in vitro baseados em cálculos in vivo podem aprimorar as dosagens para a realização de experimentos a campo.(AU)

Assuntos

RESUMO

Abstract Duddingtonia flagrans has been tested as an alternative parasite control, but data from in vitro experiments based on in vivo calculations describing nematophagous fungi predation in nematodes are restricted. The objective of this work was to determine the efficacy of D. flagrans against sheep nematode larvae in vitro using in vivo calculations. Fecal samples were introduced to fungi in different concentrations: 0.0/control; 0.05; 0.1; 0.2; 0.4; 0.8; 1.6; 3.2; and 6.4 g corresponding, respectively, to 583.000; 1.166.000; 2.332.000; 4.664.000; 9.328.000; 18.656.000; 37.312.000 and 74.624.000 chlamydospores/kg of body weight. The material was incubated for 14 days, before the larvae recovery (Assay 1). Assay 2 was carried out with the doses of 0.00625; 0.0125; and 0.025 g. The results showed a negative correlation between fungal concentrations and larval numbers for both assays. The fungus demonstrated an efficacy above 89% in both assays. Thus, we consider that the data from in vitro studies based on in vivo calculations may optimize the fungi quantities for field experiments.

Resumo Duddingtonia flagrans tem sido testado como uma alternativa no controle de parasitos, entretanto, trabalhos in vitro da predação de nematoides por fungos nematófagos correlacionados com cálculos baseados para testes in vivo são restritos. O objetivo deste trabalho foi determinar a eficácia in vitro de D. flagrans contra larvas de nematoides de ovinos tendo como base cálculos in vivo. Amostras fecais receberam a adição do fungo em diferentes concentrações: 0.0/controle; 0,05; 0,1; 0,2; 0,4; 0,8; 1,6; 3,2 e 6,4 gramas correspondendo, respectivamente, às seguintes dosagens: 583.000; 1.166.000; 2.332.000; 4.664.000; 9.328.000; 18.656.000; 37.312.000 e 74.624.000 clamidósporos/Kg de peso vivo animal. O material foi incubado por 14 dias, para recuperação das larvas (Ensaio 1). O Ensaio 2 foi realizado com concentrações de 0,00625; 0,0125 e 0,025 g. Foi observada correlação negativa entre a concentração fúngica e o número de larvas, nos dois ensaios. O fungo demonstrou eficácia acima de 89% em ambos os ensaios. A partir destes dados, acreditamos que ensaios in vitro baseados em cálculos in vivo podem aprimorar as dosagens para a realização de experimentos a campo.

Assuntos

RESUMO

Three experimental assays with Duddingtonia flagrans (isolated AC001) were carried out. The growth of the genus Duddingtonia present in formulation of rice bran, its predatory capability on Oesophagostomum spp. infective larvae (L3) in petri dishes (assay 1), its action in faecal cultures with eggs of that parasite (assay 2) and isolate's capability of predation after passing through gastrointestinal tract of swine (assay 3) was evaluated. At assay 3, feces were collected at time intervals of 12, 24, 36, 48, and 60 h after feed animals with the formulation. Assays 1 and 2 showed a statistical difference (p < 0.01) by the F test when comparing the treated group with the control group. At the both assays, was observed in the treated group a reduction percentage of 74.18% and 88.38%, respectively. In assay 3, there was a statistical difference between the treated group and the control group at all collection times (p < 0.01). Regarding the collection periods, there was no statistical difference over time in the treatment group (p > 0.05). The results demonstrate that the fungal isolate AC001 formulated in rice bran can prey on L3 of Oesophagostomum spp., in vitro and after passing through the gastrointestinal tract, without loss of viability. This isolate may be an alternative in the control of Oesophagostomum spp. in swine.

Assuntos

RESUMO

Duddingtonia flagrans has been tested as an alternative parasite control, but data from in vitro experiments based on in vivo calculations describing nematophagous fungi predation in nematodes are restricted. The objective of this work was to determine the efficacy of D. flagrans against sheep nematode larvae in vitro using in vivo calculations. Fecal samples were introduced to fungi in different concentrations: 0.0/control; 0.05; 0.1; 0.2; 0.4; 0.8; 1.6; 3.2; and 6.4 g corresponding, respectively, to 583.000; 1.166.000; 2.332.000; 4.664.000; 9.328.000; 18.656.000; 37.312.000 and 74.624.000 chlamydospores/kg of body weight. The material was incubated for 14 days, before the larvae recovery (Assay 1). Assay 2 was carried out with the doses of 0.00625; 0.0125; and 0.025 g. The results showed a negative correlation between fungal concentrations and larval numbers for both assays. The fungus demonstrated an efficacy above 89% in both assays. Thus, we consider that the data from in vitro studies based on in vivo calculations may optimize the fungi quantities for field experiments.(AU)

Duddingtonia flagrans tem sido testado como uma alternativa no controle de parasitos, entretanto, trabalhos in vitro da predação de nematoides por fungos nematófagos correlacionados com cálculos baseados para testes in vivo são restritos. O objetivo deste trabalho foi determinar a eficácia in vitro de D. flagrans contra larvas de nematoides de ovinos tendo como base cálculos in vivo. Amostras fecais receberam a adição do fungo em diferentes concentrações: 0.0/controle; 0,05; 0,1; 0,2; 0,4; 0,8; 1,6; 3,2 e 6,4 gramas correspondendo, respectivamente, às seguintes dosagens: 583.000; 1.166.000; 2.332.000; 4.664.000; 9.328.000; 18.656.000; 37.312.000 e 74.624.000 clamidósporos/Kg de peso vivo animal. O material foi incubado por 14 dias, para recuperação das larvas (Ensaio 1). O Ensaio 2 foi realizado com concentrações de 0,00625; 0,0125 e 0,025 g. Foi observada correlação negativa entre a concentração fúngica e o número de larvas, nos dois ensaios. O fungo demonstrou eficácia acima de 89% em ambos os ensaios. A partir destes dados, acreditamos que ensaios in vitro baseados em cálculos in vivo podem aprimorar as dosagens para a realização de experimentos a campo.(AU)

Assuntos