Biological activity and sporulation rate produced by two native isolates of Beauveria bassiana (Hypocreales: Clavicipitaceae) on the leaf beetles Colaspis brunnea and Cerotoma ruficornis (Coleoptera: Chrysomelidae)

In this study, the biological activity and sporulation rate produced by two native isolates (Bb-16 SOR and Bb-92 POE) of Beauveria bassiana (Balsamo-Crivelli) Vuillemin on the leaf beetles Colaspis brunnea (Fab-ricius) and Cerotoma ruficornis (Oliver) (Coleoptera: Chrysomelidae) were evaluated. Both parameters were compared with a biologically characterized B. bassiana isolate (Bb-18). The adults of these insects were treated with a concentration of 1 × 108 conidia mL-1 of each isolate. The Bb-16 SOR and Bb-92 POE iso-lates, with accumulative mortality of 97 % and 96 %, respectively, were significantly more pathogenic and virulent than the isolate Bb-18, which caused 84 % mortality. Similarly, Bb-16 SOR and Bb-92 POE isolates induced mortalities of 94 % and 91.5 % in C. ruficornis, compared to 82.2 % caused by Bb-18. The propor-tion of adults that presented sporulation was also higher in both species of insects infected by Bb-16 SOR (91 % for C. brunnea and 88 % for C. ruficornis) and Bb-92 POE (74 % for C. brunnea and 75 % for C. rufi-cornis). Furthermore, isolates Bb-16 SOR and Bb-92 POE were the fastest to kill both C. brunnea and C. ru-ficornis adults. We concluded that native isolates Bb-16 SOR and Bb-92 POE represent an important alter-native for the biocontrol of the leaf beetles C. brunnea and C. ruficornis.