In Vitro and In Vivo Induction, and Characterization of Beauvericin Isolated from Beauveria bassiana and Its Bioassay on Galleria mellonella Larvae

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Entomopathogenic fungi produce secondary metabolites which may bioactively help fungus in its virulence toward insect hosts. Beauveria bassiana produces several toxic low molecular compounds in vitro as well as in vivo, the most important of them is Beauvericin. The BEH isolate of the fungus was selected for Beauvericin assay. Beauvericin was obtained from surface and submerged cultures of the fungus in PDB and PDA, culture filtrates, and in vivo conidia harvested from insect cadavers. Results indicated that in vivo fungal conidia contained the most Beauvericin, causing a higher mortality to Galleria mellonella larvae as compared with in vitro fungal products in their different concentrations. Beauvericin chromatogram revealed that Beauvericin was in its greatest quantity in comparison with the other secondary metabolites of BEH isolate. The impact of Beauvericin on mean larval survival and on paralysis time was in agreement with bioassay data showing lower ST50 vs. higher PT50 in larvae treated with metabolites of the insect-derived conidia.