Evaluation of Metarhizium anisopliae (Deuteromycota: Hyphomycetes) for control of broad mite Polyphagotarsonemus latus (Acari: Tarsonemidae) in mulberry

A study on 12 entomopathogenic fungi for controlling broad mite (Polyphagotarsonemus latus (Banks)) in mulberry found that Metarhizium anisopliae CKM-048 was the most virulent strain in controlling both larvae and adult broad mites at the concentration of 2 x 10⁸ conidia/ml. There was no ovicidal effect when tested with broad mite eggs. Median lethal concentrations (LC₅₀) of M. anisopliae in killing larvae and adults were 8.7 x 10⁶ and 1.3 x 10⁷ conidia/ml, respectively. Median lethal times (LT₅₀) of larvae and adults were 2.4 and 3.8 days, respectively, at the concentration of 2 x 10⁸ conidia/ml. The fungus was found to produce protease and chitinase. Scanning electron microscope (SEM) studies were done to monitor the infection steps of the fungus on broad mites. A greenhouse test on mulberry trees revealed that M. anisopliae could reduce the broad mite population within 4 days after treatment. However, after 7 days, its efficacy was decreased significantly.