Correlation Between Ectoenzyme Activity and Virulence against Planococcus citri of Metarhizium anisopliae F061

The ectoenzyme activity and the virulence against Planococcus citri of Metarhizium anisopliae F061 were determined in the laboratory. Their correlation was established using a linear regression analysis. The activities of two ectoenzymes from the bacteria were high.At concentrations of 1.00×10⁸ and 1.00×10⁷ conidia·mL^-1, the protease activities of the spores were 7.63 U·mL^-1 and 7.61 U·mL^-1, respectively; while the chitinase activities, 5.45 U·mL^-1 and 5.67 U·mL^-1, respectively; and, the LT₅₀ of the strain against P.citri, 4.98 d and 5.39 d, respectively. The LT₅₀ inversely correlated significantly with the protease activity, but moderately with the chitinase activity. It appeared that the protease were stronger than the chitinase in M.anisopliae F061, and thus, played a more critical role in infecting P. citri.