Biocontrol Potential and Volatile Metabolite Profiling of Beauveria bassiana against Rotylenchulus reniformis and Fusarium oxysporum f.sp. ricini

Abstract

In the present study, the in‑vitro growth of Beauveria bassiana was assessed on three media, viz., Sabouraud Dextrose Agar (SDA), Potato Dextrose Agar (PDA), and Oatmeal Agar (OMA). The fungus showed the greatest radial expansion on SDA (7.47 cm), followed by PDA (7.17 cm) and OMA (7.07 cm). Beyond growth performance, the study examined the antimicrobial activity of B. bassiana against the reniform nematode, Rotylenchulus reniformis, and the wilt-inducing fungus, Fusarium oxysporum f. sp. ricini, and the organism’s volatile metabolite profile. Bioassays using culture filtrates from the 3 medium against Rotylenchulus reniformis juveniles recorded a highest mortality of 98.67 % at 25 % concentration of the SDA, at 96 h post inoculation. Dual‑culture tests carried out against F. oxysporum f. sp. ricini recorded the highest inhibition (57 %) against B. bassiana grown on SDA. GC‑MS analysis of B. bassiana crude extract revealed the presence of 235 compounds belonging to the classes of hydrocarbons, fatty acids and derivatives, esters, alcohols, ketones, aromatics, phenolics, and various heterocyclic/nitrogen-containing molecules. The differences observed among media types for Beauveria bassiana growth, nematode mortality, and pathogen inhibition were statistically significant (p < 0.01), confirming the reliability of the experimental outcomes. The findings highlight the significant impact of culture media on the bioactivity and metabolite production of Beauveria bassiana, emphasizing its potential as a versatile biocontrol agent. These results underscore the utility of B. bassiana as a promising component of integrated pest management (IPM) strategies, offering an environmentally sustainable approach to suppress both nematode and fungal pathogens simultaneously. Further studies are necessary to validate these results under field conditions and to develop effective formulations for use in integrated disease management strategies.