Dose-response relationship of Beauveria bassiana (Balsamo) Vuillemin on Rhipicephalus microplus ticks

Abstract Background Isolation and optimization are the primary step in the development of fungal pathogens for biological control agents. In this study, three indigenous strains of Beauveria bassiana (Bb-27, Bb-40 and Bb-41) and one commercial strain (Eco-Bb) were tested for dose/response relationship of the fungus against Rhipicephalus microplus ticks. Results We used R. microplus larvae of 2 weeks of age, and exposed them to four conidial concentrations: 1x103, 3x105, 4x107, 3.2x108 conidia.mL− 1 of each strain. Water was used as a control. Larval mortality was significantly affected by the type of formulation. There was a positive relationship between the concentration of the formulation and mortality of the treated ticks. All the ticks treated with the formulation containing 3.2x108 conidia.mL− 1 resulted in high levels of mortality. Conclusions From this study, it can be concluded that, because of the diversity in the performance of B. bassiana strains, optimization of the formulation for different Isolates of B. bassiana can be achieved through scrutinizing the virulence of the Isolates.