Host-pathogen interaction for screening potential of Metarhizium anisopliae isolates against the date-palm dust mite, Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae)

Abstract

Impact of virulence-determining traits of the fungus, Metarhizium anisopliae (Sensu lato), isolates 2049, 8762, and 7234, on mortality rate of the date-palm dust mite, Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae), and host antioxidant defense-related enzymes were evaluated. Laboratory bioassays showed significant differences in the mortality rates of the mite species against fungal infection. Isolate 2049 (LT50 = 6.43 days; LC50 = 2.37 × 106 conidia/ml) was the most virulent one, revealing (160.64%) higher activity of the cuticle-degrading Protease (Pr1) than least virulent isolate 7234 (LT50 = 18.44 days; LC50 = 2.18 × 108 conidia/ml). The invading conidial suspensions of the most virulent isolate 2049, established in the present study, successfully evaded the antioxidant-defense mechanism, and resulted in low relative enzymatic activities of the catalases, superoxide dismutases, and glutathione S-transferases, at the lateral stages of infection. The obtained results concluded that M. anisopliae isolate 2049 could be an attractive candidate for the mycopathogen development of controlling date-palm dust mite, O. afrasiaticus.