Abstract:The present study forms a part of biological control against the medfly (Ceratitis capitata) and seeks to isolate and determine the diversity of the medfly-associated entomopathogenic fungi in soil samples collected from Argane (Argania spinosa) forest, in different localities of Souss-Massa region. Search and isolation of the indigenous populations of Ceratitis capitata entomopathogenic fungi was carried out by using larvae of this pest as baits. After trapping, isolation and identification of fungal isolates, a pathogenicity test was used to select fungal strains that have significant virulence potential against the Mediterranean fruit fly. The degree of virulence was estimated by the ability of the fungus to induce the disease and/or the death in the insect and also by calculating the lethal time 50 (LT50). The obtained results were clearly demonstrated the sensitivity of medfly to tested fungal strains and particularly to strains of Fusarium sp., Aspergillus niger and Scopulariopsis sp. that have shown high mortality rates (more than 84%) and to Trichoderma harzianum, Scedosporium sp., Epicoccum sp. and Ulocladium sp. with more than 70% mortality for the two tested concentrations. Furthermore these strains showed short LT 50 (less than 83 hours). All these results confirm the presence of entomopathogenic fungi of Ceratitis capitata in Argane soil, and prove the potential of entomopathogenic fungi for biocontrol of the Mediterranean fruit fly under laboratory conditions.