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

Authors: ELGAR, SABRINA - University Of Georgia; VILLARI, CATERINA - University Of Georgia; FAIR, CONOR - University Of Georgia; Shapiro Ilan, David; CHAVEZ, DARIO - University Of Georgia; BLAAUW, BRETT - University Of Georgia

Submitted to: Frontiers in Fungal Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/5/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Peach trees are attacked by a variety of insect pests that reduce productivity. These pests are generally controlled using chemical pesticides. However, due to environmental and regulatory concerns, the development of alternative methods is desirable. Insect-killing fungi, such as the white muscardine fungus (Beauveria bassiana), are safe biopesticides that kills many economically important insect pests in various cropping systems. The fungus can be applied to plants using most standard sprayers. Interestingly, in some plants the fungus has also been documented to live inside the plant as an endophyte (an endophyte does not harm the plant). Beauvericin is a compound produced by the fungus that is toxic to insects. Thus far, very little research has been done to determine the suitability of the white muscardine fungus as a biocontrol tactic in peach systems. In this study, the ability of the white muscardine fungus to exist as an endophyte in peaches was tested, and the levels of beauvericin were measured inside the plant and on the surface of peach seedlings after the fungus was applied. Results indicated that the fungus was able to live inside the peach plant as an endophyte, but insecticidal activity was not detected and beauvericin levels were very low. In contrast, high levels of beauvericin were detected on the surface of peach seedlings (especially the leaves). Therefore, it appears the fungus may be growing on the peach seedling surface and producing insecticidal toxins. This outcome enhances the potential to use the fungus as a safe bio-pesticide in peaches.

Technical Abstract: Endophytic entomopathogenic fungi like Beauveria bassiana offer a promising avenue for sustainable pest management in agriculture, yet their interactions with woody perennial hosts and secondary metabolite dynamics remain understudied. This study investigated the capacity of B. bassiana to colonize peach (Prunus persica) seedlings endophytically and quantified production of beauvericin, a bioactive mycotoxin with known insecticidal properties. After being inoculated using soil drench or foliar spray methods, Foliar spray inoculation resulted in higher colonization of leaf tissues, while soil drench supported persistence in roots. Quantification of beauvericin revealed that levels of the toxins varied significantly by tissue type, inoculation method, and surface sterilization status. The highest concentrations occurred in non-surface-sterilized leaves of foliar-sprayed plants, measured two weeks post-inoculation. Surface sterilization before extraction sharply reduced beauvericin concentrations, suggesting that the mycotoxin is produced mostly by the epiphytic colonies, although low levels were detected internally as well. Larval bioassays performed with Tenebrio molitor showed elevated mortality associated with foliar-sprayed tissues, aligning with the observed beauvericin concentrations, which suggest a functional insecticidal role for foliar applications. Comparisons to previously reported in vivo and in vitro beauvericin levels indicate that plant surface conditions may promote localized production at levels sufficient to impact herbivores. These findings underscore the importance of inoculation method, tissue targeting, and metabolite monitoring in future applications of B. bassiana as a biocontrol agent. Future work should address how environmental factors and time influence insecticidal metabolite production in planta to better integrate fungal endophytes into biocontrol strategies.