Selection and evaluation of virulence of Beauveria bassiana (Bals.) Vuill. submitted to different temperature

Abstract

The entomopathogenic fungi Beauveria bassiana (Bals.) has been reported as  agent of Insects control. It is necessary to investigate the pathogenic activity and also factors such as temperature that might interfere their development, to make sure that could be used in biology program control. The aim of this study was to select isolates of Beauveria bassiana tolerants to high temperatures and to verify the virulence of them before and after exposure. A pre-selection was realized whereby 15 isolates were inoculated in complete medium and incubated at 30C°, 35C° and 40°C. For isolates there was an increase isolates/temperature, were evaluated the germination and colony forming units (CFU). No development of any isolated was found at temperatures of 35 and 40°C and the best percentage of germination in CFU was obtained by Unioeste 4, CG 26 and UEL 24 at 30°C that were inoculated in complete medium at 25°C and 32°C to compare of development parameters. For all isolates there was a germination delay at 32°C and there was no difference between the isolates and neither the temperatures with percentages among 80,1 and 90,4% of colonies formed in CFU. However, for conidia production there was a reduction to all isolates at 32°C. For virulence test was observed a decrease of 88% confirmed adults mortality of Alphitobius diaperinus at 32°C by Unioeste 4 confirmed mortality.