Endophytic colonization and beauvericin production by Beauveria bassiana in peach (Prunus persica) seedlings : Implications for insect biocontrol

Beauveria bassiana (Balsamo) Vuillemin is a well-known entomopathogenic fungus that occupies diverse ecological niches, including soilborne, epiphytic, and endophytic habitats. Its capacity to function as an endophyte has received growing interest for potential applications in sustainable pest management, particularly in woody perennial systems where delivery and persistence of biological control agents are challenging. This study investigated endophytic colonization of peach (Prunus persica (Batsch)) seedlings by B. bassiana and quantified production of the insecticidal secondary metabolite beauvericin in and on plant tissues. Seedlings were inoculated via foliar spray or soil drench, and fungal recovery was assessed from leaf, stem, and root tissues. Colonization patterns indicated transient systemic movement, with foliar spray favoring recovery from leaf tissues and soil drench supporting persistence in roots. Beauvericin concentrations varied significantly by tissue type, inoculation method, and surface sterilization status. The highest levels were detected in non-surface-sterilized leaves of foliar-sprayed plants, measured two weeks post-inoculation. Surface sterilization prior to extraction significantly reduced detected concentrations, suggesting that beauvericin is primarily produced by epiphytic fungal growth, although low internal concentrations were also detected. Larval bioassays with Tenebrio molitor (L.) revealed increased mortality associated with foliar-sprayed tissues, aligning with observed beauvericin levels and suggesting localized insecticidal activity. These findings demonstrate that the spatial dynamics of fungal colonization and metabolite localization are critical considerations for the effective deployment of B. bassiana in biocontrol strategies. Further research is needed to determine how environmental factors, host physiology, and time influence secondary metabolite production in planta