Physiological and pathogenical characterization of beauveria bassiana and metarhizium anisopliae isolates for management of adult spodoptera frugiperda

To know the potential of entomopathogenic fungi for management of adults of Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) using the auto-dissemination technique, three isolates of Beauveria bassiana (Balsamo-Crivelli) Vuillemin and six isolates of Metarhizium anisopliae (Metschnikoff) (Hypocreales: Clavicipitaceae) were characterized physiologically and pathogenically. At the time 50% of conidia germinated (GT50), pathogenicity, effect of relative humidity, and horizontal transmission of the entomopathogen male-female in three ratios (1:5, 1:10, 1:15) were evaluated. In addition, a preliminary device for auto-dissemination of the entomopathogen was evaluated. All isolates were pathogenic (33.3-100%) toward adults of the insect. Pathogenicity and TG50 were very correlated (r = 0.8) and fluctuated from 14.1 to 20.3 hours. Because of intermediate pathogenicity (68.7%) and varying response to humidity (62-100%), isolation of M. anisopliae Ma-San Rafel-2 was used for auto-dissemination bioassays. Transmission of the entomopathogen was a function of the number of females exposed. After 11 days, a male transmitted the fungus to 15 healthy females. The males released in devices prepared with fungus + synthetic sex pheromone were attracted, infected, and killed 5 to 8 days later. Our results are fundamental for management of S. frugiperda through auto-dissemination of entomopathogenic fungi.