RESUMO
The continued maintenance of nematophagous fungi predatory activity under laboratory conditions is one of the basic requirements for a successful biological control. The purpose of this study was to evaluate the influence of time on the preservation of the fungus Duddingtonia flagrans (AC001 and CG722) stored in silica-gel for 7 years and their subsequent predatory activity on cyathostomin L(3) larvae in 2% water-agar medium (2% WA). Samples of the isolates AC001 and CG722, originating from vials containing grains of silica-gel sterilized and stored for 7 years, were used. After obtaining fungal conidia, the predation test was conducted over 7 days on the surface of 9.0 cm Petri dishes filled with 2% WA. In the treated groups each Petri dish contained 500 cyathostomin L(3) and conidia of fungal isolates in 2% WA. In the control group (without fungi) the plates contained 500 L(3) in 2% WA. The experimental results showed that isolated AC001 and CG722 were efficient in preying on cyathostomin L(3) (p<0.01) compared to control (without fungus). However, no difference was observed (p>0.01) in the predatory activity of the fungal isolates tested. Comparing the groups, there was a significant reductions of cyathostomin L(3) (p<0.01) of 88.6% and 78.4% on average recovered from the groups treated with the isolates AC001 and CG722, respectively, after 7 days. The results of this test showed that the fungus D. flagrans (AC001 and CG722) stored in silica-gel for at least 7 years maintained its predatory activity on cyathostomin L(3).
Assuntos
Ascomicetos/patogenicidade , Preservação Biológica , Infecções Equinas por Strongyloidea/parasitologia , Strongyloidea/microbiologia , Animais , Ascomicetos/crescimento & desenvolvimento , Fezes/parasitologia , Cavalos , Larva/microbiologia , Controle Biológico de Vetores/normas , Sílica Gel , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/patogenicidade , Fatores de TempoRESUMO
The viability of a fungal formulation using the nematode-trapping fungus Duddingtonia flagrans was assessed for the biological control of horse cyathostomin. Two groups (fungus-treated and control without fungus treatment), consisting of eight crossbred mares (3-18 years of age) were fed on Cynodon sp. pasture naturally infected with equine cyathostome larvae. Each animal of the treated group received oral doses of sodium alginate mycelial pellets (1g/(10 kg live weight week)), during 6 months. Significant reduction (p<0.01) in the number of eggs per gram of feces and coprocultures was found for animals of the fungus-treated group compared with the control group. There was difference (p<0.01) of 78.5% reduction in herbage samples collected up to (0-20 cm) between the fungus-treated group and the control group, during the experimental period (May-October). Difference of 82.5% (p<0.01) was found between the fungus-treated group and the control group in the sampling distance (20-40 cm) from fecal pats. During the last 3 months of the experimental period (August, September and October), fungus-treated mares had significant weight gain (p<0.01) compared with the control group, an increment of 38 kg. The treatment with sodium alginate pellets containing the nematode-trapping fungus D. flagrans reduced cyathostomin in tropical southeastern Brazil and could be an effective tool for biological control of this parasitic nematode in horses.