Susceptibility of different life stages of Ornithodoros lahorensis to entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana.

The use of chemicals for the control of arthropod pests can be problematic due to the potential for both environmental contamination and resistance development. As a result, there is an increasing interest in nonchemical alternatives, such as biocontrol by entomopathogenic fungi. In the present study, three strains of Metarhizium anisopliae (V245, 3247, and 4456) and one strain of Beauveria bassiana (LM 3.2) were evaluated under laboratory conditions for their virulence towards three life stages of Ornithodoros lahorensis. Groups of eggs, larvae, and adult ticks were treated by immersion in two different suspensions (10(5) and 10(7) conidia/ml) of each fungal strain. All treatment and control groups were observed during a 3-week period, and the hatchability of eggs and mortality percentage of larvae and adult ticks were assessed. The effect of fungal strains on egg hatchability and larva and adult mortality was significant and dose dependent compared to the control groups (P < 0.05). The results also showed that the greatest biopesticidal effect was due to strain 4456 of M. anisopliae and LM 3.2 strain of B. bassiana at all tested concentrations, making these fungi potential biological control agents of O. lahorensis reducing the use of chemical acaricides.