Nomuraea rileyi as biological control agents of Rhipicephalus microplus tick

Nomuraea rileyi , a fungus pathogenic to insects, has been widely used for biological control of agricultural pests in Brazil. This study investigates the effects of N . rileyi , isolates Nr 138, Nr 151, and Nr 177, to eggs, larvae, and engorged females of Rhipicephalus microplus tick. Specimens were immersed in 1 ml of conidial suspension for 3 min, whereas the control group was immersed in 0.01 % Tween 80 water solution. The isolate Nr 138 controlled 67.37 % of ticks when the highest conidial concentration was used, 10 8 conidia ml −1 . The isolate Nr 177 significantly reduced the percentage of hatch of larvae from eggs treated with 10 8 conidia ml −1 . Conversely, the isolate Nr 151 was not virulent to eggs, larvae, or adults. Variability in virulence was observed among the N . rileyi isolates investigated in the current study—Nr 138 was more virulent to engorged females, while Nr 177 was more virulent to unfed larvae. Although N . rileyi proved to be virulent to several stages of R . microplus , the results obtained in this study indicate that N . rileyi does not appear to be a remarkable biological control agent for R . microplus .