Distribution of the Metarhizium anisopliae species complex in Mexico: analysis of Chihuahuan desert, subtropical, and Mesoamerican isolates

The traditional species of entomopathogenic fungus, M. anisopliae, is currently considered a species complex of morphologically very similar species, including at least eight distinct, molecularly identifiable taxa; M. anisopliae, M. robertsii, M. brunneum, M. globosum, M. guizhouense, M. pingsahense, M. acridum and M. majus. Here we identified Mexican isolates of Metarhizium anisopliae sensu lato, from desert, subtropical and tropical zones in Mexico, using RFLP of EF-1α band patterns, and compared these to those found in Ontario, Canada. Molecular analysis revealed that at least two species of Metarhizium occur in Mexico, M. robertsii and M. brunneum “alternate”. By comparison, in Ontario these occur also, and additionally “typical” M. brunneum, and M. guizohuense. In Mexico, M. brunneum "alternate" was more abundant in lowland, tropical and subtropical locations, in the states of Nuevo Leon, Veracruz, Tamaulipas, Chiapas, Colima and Tabasco, while M. robertsii was more common in drier, temperate climates of the highlands of Coahuila and San Luis Potosi. The “alternate” M. brunneum profile shared 99.2% identity with the “typical” M. brunneum EF-1α gene  sequence. Precise characterization will associate biological parameters (such as virulence) to different species (M. brunneum, M. robertsii, etc.) and allow better decision-making during selection of isolates for biological control projects.