CARACTERIZACIÓN DE SECRECIONES DE Beauveria bassiana Y Metarhizium anisopliae CON ACTIVIDAD PATOGÉNICA CONTRA EL GORGOJO DEL FRIJOL Acanthoscelides obtectus.

Abstract

Ten isolates of Beauveria bassiana and Metarhizium anisopliae were selected in this work from the entomopathogenic fungi collection at CIIDIR - Sinaloa, these isolates were subcultured using Potato Dextrose Agar (PDA) culture medium for isolates maintenance. Bioassays were used to determine which isolates were most pathogenic, and caused mortality of Acanthoscelides obtectus. In addition, virulence parameters CL50 and TL50 of the highly pathogenic isolates were determined. Two isolates of B. bassiana AGG24 and M. anisopliae AGG28 were selected due to their highest mortality, and then the extracellular secretions were analyzed in the culture medium containing 1 % of powdered insect (induced medium), as well as in the medium without insect (non induced medium). The isolates Bb AGG24 and Ma AGG28 presented the highest pathogenicity causing a mortality rate of 84.9 and 64% respectively. CL50 and TL50 was determined for each one. Bb AGG24 presented a CL50 of 9.2 x 104 conidia/mL with 8.2 x 104 and 8.1 x 105 conidia/mL as upper and lower confidence limits respectively and a TL50 of 2 days, with 1.9-2.1 days as limits, while Ma AGG28 showed a CL50 of 1.6 x 106 conidia/mL, 3.5 x 105 to 5.1 x 106 conidia/mL of confidence limits and 2.7 days with 2.6 to 2.8 days as limits. To characterize the extracellular proteins secreted by B. bassiana and M. anisopliae four protein extraction methods were evaluated, determining that the precipitation with ammonium acetate 0.1 M in absolute methanol was the most efficient method in terms of resolution and quality. Protein characterization results using the GelScape software revealed a total of 40 clear spots in secretions of B. bassiana in a range of pH from 5.6 to 7.5 and a molecular mass from 19 to 102 kDa, while M. anisopliae spots were observed in a pH range from 4.4 to 9.3 and a molecular mass from 15 to 120 kDa.