Search

This research reported the in vitro pathogenicity of Verticillium lecanii strains, L2 and L5, and Beauveria bassiana strains, B76 and B252, against Megoura japonica using leaf-dip method. The virulence potential of these four entomopathogenic fungal strains of V. lecanii and of B. bassiana were compared between fungi conidia (concentrations 1 × 106, 1 × 107, and 1 × 108 conidia mL−1) and culture filtrate. Moreover, binary combination of four different fungal strains (L2 + B76, B76 + L5, L2 + B252, and L2 + B76 + B252 + L5) were evaluated against M. japonica under control condition. Aphid mortality was recorded after two, four, six, and eight days of post-treatment. In the conidial concentration bioassay, strain B76 showed maximal mortality (85.3%) against bean aphid, and strain L5 showed the lowest effect (60.0%) at the highest concentration (1 × 108 conidia mL−1) at eight days post-treatment. Whereas, binary combinations of B76 and L2 strains showed the highest effect against M. japonica (90.5%) than other combinations. Moreover, in comparison with the effect of filtrate and conidia bioassay, 91.4% and 84.1% were achieved in strain B76, and the lowest effect (63.8% and 55.1%) was recorded in strain L5.

The importance of having a technique that allows an efficient expression of symptoms of anthracnose is based on the early differentiation of cultivars and the optimization of genetic, material and financial resources. The objective of this research was to generate an alternative inoculation technique for Colletotrichum gloeosporioides on mango for early anthracnose tolerance screening. On this technique was optimized some of the most relevant components such as isolate virulence, conidial density, the inoculum deposition on leaves and using of surfactants. The study was carried in Iguala, Mexico, during the production cycles 2015-2016. C. gloeosporioides was biologically and culturally characterized. Gro and Sin monosporic strains were isolated from leaves, flowers, fruits and branches with anthracnose symptoms from commercial mango orchards located in Guerrero and Sinaloa states, Mexico. These strains show mycelial growth at 2.2 and 2.1 cm of diameter per day, spore density of 4.3x106, 3.9x106 conidia/ml, germination of 27 and 26%, virulence, with incubation period 4.5 and 4.1 days after inoculation, incidence of 90 and 92% and severity of 3.2 and 3.5 cm of diameter. The highest incidence and severity values with the lowest incubation period, was obtained using Gro isolate (1x105 conidia/ml) and polyoxyethylene-20-sorbitan monolaurate as spreader-sticker inoculated on the abaxial surface on detached young leaves, 15-20 days old, with a soft brush and incubated under dark condition. This inoculation technique allowed the optimal expression of C. gloeosporioides virulence in mango leaves and could be incorporated as a tool in the early differentiation of tolerance and susceptibility among cultivars.

The importance of having a technique that allows an efficient expression of symptoms of anthracnose is based on the early differentiation of cultivars and the optimization of genetic, material and financial resources. The objective of this research was to generate an alternative inoculation technique for Colletotrichum gloeosporioides on mango for early anthracnose tolerance screening. On this technique was optimized some of the most relevant components such as isolate virulence, conidial density, the inoculum deposition on leaves and using of surfactants. The study was carried in Iguala, Mexico, during the production cycles 2015-2016. C. gloeosporioides was biologically and culturally characterized. Gro and Sin monosporic strains were isolated from leaves, flowers, fruits and branches with anthracnose symptoms from commercial mango orchards located in Guerrero and Sinaloa states, Mexico. These strains show mycelial growth at 2.2 and 2.1 cm of diameter per day, spore density of 4.3×106, 3.9×106 conidia/ml, germination of 27 and 26%, virulence, with incubation period 4.5 and 4.1 days after inoculation, incidence of 90 and 92% and severity of 3.2 and 3.5 cm of diameter. The highest incidence and severity values with the lowest incubation period, was obtained using Gro isolate (1×105 conidia/ml) and polyoxyethylene-20-sorbitan monolaurate as spreader-sticker inoculated on the abaxial surface on detached young leaves, 15-20 days old, with a soft brush and incubated under dark condition. This inoculation technique allowed the optimal expression of C. gloeosporioides virulence in mango leaves and could be incorporated as a tool in the early differentiation of tolerance and susceptibility among cultivars. [ABSTRACT FROM AUTHOR]

This research reported the in vitro pathogenicity of Verticillium lecanii strains, L2 and L5, and Beauveria bassiana strains, B76 and B252, against Megoura japonica using leaf-dip method. The virulence potential of these four entomopathogenic fungal strains of V. lecanii and of B. bassiana were compared between fungi conidia (concentrations 1 × 106, 1 × 107, and 1 × 108 conidia mL−1) and culture filtrate. Moreover, binary combination of four different fungal strains (L2 + B76, B76 + L5, L2 + B252, and L2 + B76 + B252 + L5) were evaluated against M. japonica under control condition. Aphid mortality was recorded after two, four, six, and eight days of post-treatment. In the conidial concentration bioassay, strain B76 showed maximal mortality (85.3%) against bean aphid, and strain L5 showed the lowest effect (60.0%) at the highest concentration (1 × 108 conidia mL−1) at eight days post-treatment. Whereas, binary combinations of B76 and L2 strains showed the highest effect against M. japonica (90.5%) than other combinations. Moreover, in comparison with the effect of filtrate and conidia bioassay, 91.4% and 84.1% were achieved in strain B76, and the lowest effect (63.8% and 55.1%) was recorded in strain L5. [ABSTRACT FROM AUTHOR]

Using transmission electron microscopy, we studied the presence of melanin and cell wall thickness of clinical isolates of Sporothrix schenckii obtained from cats, dogs and humans as compared to reference strains. We detected differences regarding presence of the melanin among the clinical isolates of S. schenckii and a correlation between presence of melanin and cell wall thickness.