Virulence, proteolytic and lipolytic activities of Brazilian Beauveria bassiana s.l. isolates (Hypocreales: Clavicipitaceae) to Rhipicephalus microplus ticks (Acari: Ixodidae).

Beauveria bassianas.l. is a cosmopolitan fungus used in the control of different species of arthropods. The current study explored the virulence for ticks, proteolytic and lipolytic activities of 10 BrazilianB. bassianas.l. isolates. For this purpose,Rhipicephalus microplusbiological parameters was evaluated after immersion of the engorged females in fungal suspension (108conidia mL−1) and the enzymatic activities were performed posteriorly the fungal growth in minimal medium. After the biological assays, five isolates changed all parameters analysed with highest efficacy of approximately 61% (CG 206) and 66% (CG 481). However, we observed that the most virulent isolates did not show the highest enzymatic activities. Interestingly, CG 500, considered an isolate of intermediate efficacy, demonstrated higher enzymatic activities than the other isolates in four of five analyses (total protease, Pr1, Pr2 and lipase;p < .05). Based on these data, it seems reasonable to suggest that these enzymatic activities should not be used as markers of virulence for these fungal isolates. It is noteworthy that complementary studies regarding chitinase analyses, gene expression, production of toxins and hydrophobicity of conidia can be used in the selection of pathogenic isolates. [ABSTRACT FROM PUBLISHER]