ResumenEl presente trabajo informa la detección, por métodos bioquímicos, de enzimas extracelulares relacionadas con la actividad biológica de nueve cepas del complejo Metarhizium anisopliae (Metsch.) Sorokin. Se determinó, a diferentes concentraciones, la capacidad patogénica contra el insecto Cylas formicarius Fabricius, y se calculó el tiempo y la concentración letal. Se analizó tanto la presencia de enzimas extracelulares en las cepas fúngicas como su relación con el efecto entomopatogénico y virulencia contra C. formicarius. Todas las cepas del complejo M. anisopliae estudiadas resultaron patogénicas exhibiendo un índice de actividad enzimática superior a 1. La cepa LBM-30 fue la más eficiente al detectarse la presencia de enzimas proteasa, quitinasa, caseínasa, amilasa y lipasa. Esto corrobora la relación de la actividad enzimática con la virulencia observada.Palabras clave: actividad patogénica, actividad enzimática, control biológico, coleóptero, hongos entomopatógenos, virulencia AbstractThis study reports the detection, by biochemical methods, of extracellular enzymes related to the biological activity of nine strains of the complex Metarhizium anisopliae (Metsch.) Sorokin. We determined the pathogenic capacity against the insect Cylas formicarius Fabricius at different concentrations, calculated the lethal time and concentration, and analyzed both the presence of extracellular enzymes in the fungal strains as well as their relation to the entomopathogenic effect and virulence against C. formicarius. All strains of the M. anisopliae complex studied were pathogenic with an enzymatic activity index greater than 1. The LBM-30 strain was the most effective with presence of protease, chitinase, caseinase, amylase and lipase enzymes. This result corroborates the relationship between of the enzymatic activity with the observed virulence.

The efficacy of entomopathogenic fungi in the field depends on the influence of various environmental factors, including temperature and level of exposure to UV light. It is hypothesized that temperature and level of UV light exposure of Metarhizium anisopliae (Hypocreales, Clavicipiceae) may affect its efficiency in controlling the sweetpotato weevil (Cylas formicarius, Fabricius; Coleoptera, Brentidae). The objective of this study was to evaluate the influence of temperature and ultraviolet light radiation on the growth and pathogenicity of different native strains of Cuban origin of the M. anisopliae Sorokin complex with biological activity against C. formicarius. Colony diameter was measured at 28, 30, 32 and 34 °C temperature and exposed to ultraviolet light (254 nm) for 10, 15, 20, 30, 30, 60 and 120 minutes. Under laboratory conditions, the percentage germination of conidia of strains LBMa-11, LBM-30, LBM-41 and LBM-146 was determined, as well as their pathogenic capacity by means of bioassays with adults of C. formicarius in terms of the percentage of cumulative mortality and the mean lethal time (TL50). Results proved that temperature and UV light affect the ability of M. anisopliae to control C. formicarius. A delay in cumulative mortality was detected for all strains exposed to UV light, with an increase in TL50. The optimum temperature range was between 28 and 30 °C. The strain LBM-127 showed the highest sensitivity to temperature, LBMa-11 the highest tolerance to UV light, and LBM-146 was the most virulent according to Probit regression analysis.