Efficacy of the entomopathogenic fungus Beauveria bassiana in protecting date palm against the red palm weevil Rhynchophorus ferrugineus under hot desert climate

The red palm weevil ( Rhynchophorus ferrugineus ; RPW) is an important pest threatening date palm cultivation worldwide. Conventional insecticide-based management is limited by environmental concerns and the development of resistance in RPW populations. Entomopathogenic fungi (EPF), such as Beauveria bassiana , offer a promising biocontrol alternative. While laboratory and semifield studies have demonstrated their potential as insecticides, evidence from field-scale applications under diverse environmental conditions remains scarce. This study evaluated the seasonal efficacy and persistence of B. bassiana as a preventive treatment against RPW in male and female date palm groves subjected to different cultivation practices in Israel's Arava region. Healthy palms were equipped with IoTree sensors to monitor RPW infestation dynamics. EPF treatments were applied at the start of each season, and control trees were left untreated. Soil samples were collected seasonally to quantify fungal colony-forming units (CFUs) and assess their association with treatment outcomes. Results demonstrated a significant seasonal influence on EPF efficacy, with autumn treatments yielding the highest reduction in infestation rates, and summer applications showing limited effectiveness. Efficacy also varied between grove types: spring applications were most effective in male groves, whereas autumn treatments were superior in female groves. A positive correlation was found between B. bassiana CFUs in the soil and palm health, indicating that EPF persistence enhances treatment success. These findings highlight the importance of seasonal and site-specific optimization of EPF-based biocontrol strategies. Further research is needed to refine application schedules and validate outcomes across larger-scale trials.