Investigation of the bioinsecticide Beauveria bassiana as a fungal endophyte in peach (Prunus persica) seedlings

Peach (Prunus persica) is an economically important crop in the USA of which several insect pests can substantially impact production. Beauveria bassiana is a commercialized fungal entomopathogen that can colonize tissues of many crop species as an endophyte, subsequently suppressing insect pests when present in tissues. The objectives of this study were to determine if B. bassiana can be established as an endophyte in peach tissues, investigate the dynamics of fungal colonization over time, and validate that tissues containing B. bassiana are pathogenic to insects. Results indicate B. bassiana can colonize roots, stems, and leaves of peach seedlings soil drenched or foliar sprayed with a conidial inoculum. Plants foliar sprayed retained the fungus significantly more in leaves compared to roots and stems, while soil drenched plants significantly retained B. bassiana in roots and stems compared to foliar sprayed. Establishment was verified through re-isolation of the fungus via tissue culture, morphological observation, and molecular verification. Additionally, peach tissues containing B. bassiana were demonstrated to be pathogenic to insects by utilizing the mealworm (Tenebrio molitor) as a host in a tissue-feeding assay. The mortality and re-isolation of B. bassiana from mealworms was increased with surface –sterilized inoculated plant tissues, relative to untreated tissues. Our study verifies B. bassiana can become endophytic in peach tissues and they are pathogenic to insects, indicating its potential for pest management. More research is required to investigate this endophytic approach's utility through investigation of efficacy in targeting insect pests of peach and evaluation under field conditions.