Occurrence and characterization of entomopathogenic fungi from the complex of sugarcane borer Diatraea spp. in Colombia

Abstract: Panela is a solid piece of unrefined sucrose obtained from evaporation of sugarcane juice, a very important industry and source of employment in Colombia. Panela yield depends of sucrose content in sugarcane, characteristic seriously affected by the presence of the stem borers’ complex, difficultly controlled by chemical insecticides. Biological control by using microorganisms is an interesting tool for controlling this pest, which has been poor developed. The aim of this work was to isolate and characterize entomopathogenic fungi naturally infecting Diatraea spp. larvae in sugarcane crops for panela production in Colombia. Larvae were collected from three different production areas and maintained in quarantine until dead. A total of 445 larvae were collected and 23 presented fungal growth after dead. One isolate of Beauveria sp. (Bc3j-22) was obtained, which caused 83.3% and 73.3% of mortality of Diatraea indiginella and Diatraea saccharalis larvae, respectively. Sequence analysis of three genomic regions (rDNA 18S, ITS and EF1-α) allowed to classify Bc3j-22 isolate as Beauveria bassiana. This isolate showed high susceptibility to ultraviolet radiation type B (900 μW/cm2), with 33%, 49% and 81% of inactivation after 30, 40 y 50 minutes of irradiation, respectively. Optimal conditions for fungal growth were 25 °C and pH 7.0. Isolate Bc3j-22 showed high potential for controlling different species of the sugarcane borer and constitute the base for the development of a new biopesticide.