Project description:P2 is a spontaneous mutant selected from P1, an entomopathogenic fungus Beauveria bassiana that hyper-produces extracellular protease(s), compared to P1. The major expressed serine protease, called SBP, is shown to be up-regulated at the transcriptional level in the P2 mutant strain. The insecticidal potential of P1 and P2 strains was evaluated against Tuta absoluta larvae under laboratory conditions. Both strains are effective but P2 showed stronger effect than P1. Median lethal concentration (LC50) of P2 is 26 fold lower than that of P1. Median lethal times (LT50) of P1 and P2 are 4.38 and 0.84 days using 105 conidia ml-1. Enzymatic assays analysis showed that extracellular enzymes are differently expressed by the two strains, especially proteases and chitinases. Two-dimensional gel electrophoresis and mass spectrometry analysis confirmed the overexpression by P2 strain of protease and chitinase and revealed further the over-expression of several protease isoforms. Here we show a direct link between fungal enzymatic profile and insect’s pathogenesis, giving a molecular explanation for the insecticidal potential of B. bassiana fungus.