CEPAVE   05420
CENTRO DE ESTUDIOS PARASITOLOGICOS Y DE VECTORES
Unidad Ejecutora - UE
artículos
Título:
Pathogenic and enzyme activities of the entomopathogenic fungus Tolypocladium cylindrosporum (Ascomycota: Hypocreales) from Tierra del Fuego, Argentina.
Autor/es:
SCORSETTI ANA CLARA; ELIADES LORENA ALEJANDRA; STENGLEIN SEBASTIAN ALBERTO; CABELLO MARTA NOEMI; PELIZZA SEBASTIAN ALBERTO; SAPARRAT MARIO
Revista:
REVISTA DE BIOLOGíA TROPICAL
Editorial:
REVISTA DE BIOLOGIA TROPICAL
Referencias:
Lugar: San José de Costa Rica; Año: 2012 vol. 60 p. 833 - 841
ISSN:
0034-7744
Resumen:
Tolypocladium cylindrosporum is an entomopathogenic fungi that has been studied as a biological control agent against insects of several orders. The fungus has been isolated from the soil as well as from insects of the orders Coleoptera, Lepidoptera, Diptera and Hymenoptera. In this study, we have analyzed the ability of a strain of T. cylindrosporum isolated from soil from Tierra del Fuego (Argentina) to produce hydrolytic enzymes and the relationship of those activities to the fungus pathogenicity against pest aphids. We have made the traditional and molecular characterization of this strain of T. cylindrosporum. The expression of hydrolase activity in the fungal strain was estimated at three temperatures of incubation (4ºC, 12ºC and 24ºC) on different agar media supplemented with the following specific substrates: chitin azure, Tween® 20, casein, and urea for chitinase, lipase, protease, and urease activity, respectively.The hydrolytic-enzyme activity was estimated qualitatively according to the presence of a halo of clarification through hydrolase action and was expressed semiquantitatively as the ratio between the hydrolytic-halo and colony diameters. The pathogenicity of the fungus was tested on adults of the aphid Rhopalosiphum padi at three temperatures of incubation (4ºC, 12ºC and 24ºC). The suspension was adjusted to a concentration of 1 x 107 conidia ml-1. In pathogenicity assays at seven days post-inoculation the fungus caused the mortality of adults of Ropalosiphum padi at different temperatures and also showed a broad ability to grow on several agar-culture media supplemented with different carbon sources at the three incubation temperatures tested. Although the growth was greater at the higher incubation temperatures (with maximum levels at 24°C), the fungus reached similar colony diameters after 15 days of incubation on the medium supplemented with Tween® 20 at the lower two incubation temperatures of 4°C or 12°C. In accordance with the results on colony diameters, the fungus revealed an ability to degrade casein, chitin derivatives, Tween®20, and urea as evidenced by the appearance of a halo around the fungal colony. Because of its origin and temperature tolerance, this Argentine strain has great potential for use as a biocontrol agent of insect pest in cold and temperate environments.