Conchita Toriello, Armando Pérez-Torres, Fabiola Vega-García, Hortensia Navarro-Barranco, Amelia Pérez-Mejía, Marte Lorenzana-Jiménez, Victor Hernández-Velázquez, Teresa Mier
Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México D.F. 04510, México.
Metarhizium anisopliae var. acridum, monospore culture EH-502/8 (CNRCB MaPL40), isolated in Mexico from Schistocerca piceifrons ssp. piceifrons (Orthoptera: Acrididae) was tested for acute oral intragastric pathogenicity and toxicity in CD-1 mice. Animals were inoculated with one dose (108 conidia/animal) of viable (72 mice), non-viable (24 mice) conidia and compared to 18 control mice. Clinical observations were done daily; mycological and histological tests were performed during necropsies after the inoculation. No mice showed clinical symptoms of illness or died during the study. The fungus was able to persist in some organs until day 3, but did not cause any damage to the host. The gross pathology observed was splenomegaly in mice inoculated with viable and non-viable conidia. Non-germinated conidia, observed in several organs, suggest hematogenous spread, but without any histopathological tissue reaction. Results support the non-pathogenic and non-toxic status of this fungal strain when administered in a single intragastric dose to mice.