Inoculation methods and virulence of Beauveria bassiana (Bals.) Vuill. to Cosmopolites sordidus (Germar) (Coleoptera:Curculionidae) in laboratory

Abstract

The research aimed to assess different inoculation methods of Beauveria bassiana (Bals.) Vuill. on Cosmopolites sordidus (Germar) adults, in laboratory conditions on an isolates selection bioassay. Conidial suspensions of UEL151 strain were applied on insects through the following methods: spray, immersion, dorsal and ventral topical. Low mortalities were achieved for all inoculation methods, with a higher value for immersion (21.7%) at 37 days after application (DAA), as the rest of methods were significantly lower. The evaluation must be extended to a maximum of 22 DAA because the sporulation rate (confirmed mortality / total mortality) decreased with time in all methods, with values of 95.8 and 75.3%, at 22 and 37 DAA, respectively, on the immersion method. Dorsal and ventral topical methods caused not significant C. sordidus virulence, so new tests are necessary with different fungus concentrations.