Impact of Conservation in Solid Media on the Pathogenic Characteristics of Metarhizium Sp.

Ten entomopathogenic local isolates of Metarhizium sp., maintained on artificial media for three years, lost their pathogenicity. This study aimed to restore the pathogenicity of the fungus by inoculating banana black weevil, Cosmopolites sordidus (Germar, 1824) in the laboratory. Results showed a consistent restoration of pathogenic properties. The time required to kill 100 weevils decreased from 12.7 days before activation to 7.7 days after activation. The Lethal Time 50 (LT50) reduced from 7.9 days during Activation 0 to 6.2 days in Activation 2. Latency time decreased from 4.7 to 3.2 days between Activation 0 and 2. Sporulation increased from 1.55 × 10⁷ spores/ ml to 4.44 × 10⁷ spores/ ml, while mycelial appearance time on dead weevils reduced from 3.17 days to 2.29 days. The study concludes that assessing entomopathogenic fungi requires prior activation.