Contribution of the horizontal transmission of the entomopathogenic fungus Beauveria bassiana to the overall performance of a fungal powder formulation against Triatoma infestans

Abstract

Control of domiciliated Triatoma infestans, the major Chagas disease vector in southern South America, is currently achieved by indoor residual spraying of infested houses with chemical insecticides. However, in recent years this strategy has been threatened by the emergence of pyrethroid-resistant bug populations. As an alternative approach, we have previously demonstrated the efficacy of the entomopathogenic fungus Beauveria bassiana to control T. infestans bugs regardless of their pyrethroid susceptibility. In this work, we tested the virulence and residual activity of a powdered fungal formulation, and studied the significance of the horizontal transmission process (autodissemination) to fungal infection of bugs. The B. bassiana-based formulation was highly virulent against all T. infestans stages, and maintained its insecticidal capability for at least 5 months under natural ambient conditions. We showed that horizontal transmission of conidia is associated to bug density, and contributes significantly to the overall population infection event.