GENETIC DIVERSITY OF METARHIZIUM ANISOPLIAE FROM SUGARCANE FIELDS IN TABASCO STATE, MEXICO

Metarhizium anisopliae (Metschn.) Sorokin (Moniliales: Moniliaceae) is an entomopathogenic fungus used as a biological control agent against the sugarcane froghopper Aeneolamia postica (Wlk.) (Hemiptera: Cercopidae), one of the main insect pests of sugarcane in Tabasco State, Mexico. Since 2005, multiple isolates of M. anisopliae have been applied by farmers in the crop areas; however, the current genetic diversity of the fungus population in the field is unknown. The aim of this study was to characterise isolates of M. anisopliae collected in sugarcane fields to better understand their genetic and virulence characteristics against A. postica. In particular, the impact of introduced isolates on the genetic diversity of native strains was determined. Sampling of mycosed insects was conducted in soils from the main sugarcane fields of Tabasco. Twenty isolates of M. anisopliae were obtained and a monosporic culture from each one was used for the characterisation studies. The isolates were characterised using both morphological characteristics and rDNA analysis. The genetic diversity of the fungus was analysed by means of RAPD molecular markers. One of the isolates was significantly similar to the isolate introduced by farmers. RAPD analysis revealed a homogeneous group among the native isolates collected in sugarcane fields in Tabasco. These results suggest a very low incidence of recombination between native and introduced isolates. The implications of the findings on the genetic diversity of M. anisopliae and the use of this pathogen for biological control products for A. postica are discussed in this paper.