Metarhizium anisopliae (Ascomycota: Hypocreales): an effective alternative to chemical acaricides against different developmental stages of fowl tick Argas persicus (Acari: Argasidae).

The fowl bloodsucking tick Argas persicus is of great medical and veterinary importance in tropical and subtropical regions because of its role as vector of certain parasitic, bacterial and viral pathogens. A variety of acaricides are used for the control of tick infestation in poultry, resulting in environmental contamination and the development of resistance. In order to develop an alternative control method, the efficacy of three strains (V245, 685 and 715C) of entomopathogenic fungus Metarhizium anisopliae against different life stages of A. persicus including eggs, larvae, unfed and engorged adult females was evaluated under laboratory conditions. Five concentrations of different strains of M. anisopliae ranging from 10(3) to 10(7)conidia/ml were utilized. The effects of fungal strains on egg hatchability and larva and adult female mortality were significant and dose-dependent compared to the control groups (P<0.05). The mortality rates of larvae ranged from 92% to 100% for two different concentrations (10(3) and 10(4)conidia/ml) of M. anisopliae strains. Treated engorged females were more susceptible than the unfed females reaching mortality rate of 100% at the highest concentration (10(7)conidia/ml) at 18 days post-inoculation. Among strains used in this study, V245 was the most virulent strain regarding the LC(50) values for adult females exposed to fungal conidia. The results demonstrate that the application of M. anisopliae as a biocontrol agent is a promising option in reducing the use of chemical acaricides, resulting in benefits to poultry and the environment.