In vivo compatibility between Beauveria bassiana (Bals.) Vuillemin and castor oil on Hypothenemus hampei (Ferrari)

Abstract

The degree of in vivo compatibility between the entomopathogenic fungi Beauveria bassiana (Bals.) Vuillemin (Ascomycota: Hypocreales) and castor oil is important, as the interaction can be additive, synergistic or antagonistic. Thus, the objective of this study was to evaluate the in vivo compatibility between castor oil and B. bassiana on the coffee berry borer. The CCA-UFES/Bb-4 isolate of B. bassiana was used in concentrations of 0.0 (control), 1 x 104, 1 x 105, 1 x 106 and 1 x 107 conidia mL-1. The concentrations of castor oil were: 0.0 (control), 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0% v v-1. The total and confirmed mortality were evaluated, and data submitted to variance analysis. To verify the effect of B. bassiana and castor oil concentrations, the data were submitted to regression analysis at 5% probability. Castor oil had an antagonistic effect on B. bassiana reducing the mortality of coffee berry borer. The mortality of H. hampei reduced caused by interaction between B. bassiana and castor oil, due to increasing concentration of castor oil. Lower interference of castor oil was observed for high concentrations of B. bassiana. Based on the results, management of H. hampei cannot be normally performed using the association between castor bean oil and B. bassiana, except if the economic viability of the higher concentrations justified.