<p>Host-associated bioprospecting of naturally infected insects provides a valuable approach for recovering indigenous entomopathogenic microorganisms adapted to local environments. In this exploratory study, seven microbial isolates (Four fungal and three bacterial) were recovered from naturally infected <i>Opisina arenosella</i> exhibiting signs of mycosis. Their pathogenicity was evaluated under laboratory conditions against larvae of the red palm weevil (RPW, <i>Rhynchophorus ferrugineus</i>). Among the recovered isolates, a single fungal isolate was identified as <i>Beauveria bassiana</i> (Zeb-01) and showed greater virulence compared with the other isolates obtained in this study. Morphological characterization using light and scanning electron microscopy, combined with molecular identification based on ITS and EF1-α sequencing, confirmed the identity of Zeb-01 and described its hyphal and conidial features. In laboratory bioassays, Zeb-01 caused dose- and time-dependent mortality, reaching 85% larval and 86% adult mortality at 1.0 × 10¹⁰ conidia/mL within 10 days. At the lowest tested concentration (1.0 × 10⁶ conidia/mL), mortality rates of 35% and 50% were recorded for larvae and adults, respectively. When evaluated under the same experimental conditions alongside a commercial <i>B. bassiana</i> formulation, Zeb-01 exhibited lower LC₅₀ and LT₅₀ values. These results document the isolation, identification, and laboratory evaluation of a single native <i>B. bassiana</i> isolate recovered from <i>O. arenosella</i>, and demonstrate its entomopathogenic activity against RPW, indicating its potential relevance for integrated pest management programs (IPM).</p> Graphical abstract <p></p>