Determina？？o da CL90 e TL90 do isolado IBCB66 de Beauveria bassiana (Ascomycetes: Clavicipitaceae) para o controle de Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

the objective of this research was to evaluate the pathogenicity and the virulence of the ibcb66 isolate of beauveria bassiana on infected larvae of rhipicephalus (boophilus) microplus. the ibcb66 fungus strain was used as standard isolates of b. bassiana against r. (b.) microplus larvae. the larval bioassay tests using the ibcb66 isolate were carried out to determine the (lethal concentration) lc50, lc90, (lethal time) lt50 and lt90. the ibcb66 fungus strain was tested at six different concentrations (5 × 106, 107, 5 × 107, 108, 5 × 108 and 109 conidia.ml-1) to determine the percentage of larval mortality. in addition, a probit analysis was also performed. total larval mortality was observed eighteen days after the beginning of the test in the group treated with 5 × 109 conidia.ml-1. the lc50 and lc90 were 3 × 107 and 5 × 108 respectively and the lt50 and lt90 were 10 and 16 days.