Agroecological management is associated with higher recovery of native Beauveria bassiana isolates and greater laboratory virulence of selected isolates against Piezodorus guildinii

Abstract

ABSTRACT Entomopathogenic fungi of the genus Beauveria are key biological control agents in agroecosystems; however, their abundance and virulence may vary according to agricultural management practices. This study evaluated the abundance, molecular identity, and virulence potential of Beauveria isolates recovered from agroecological and conventional common bean fields against the stink bug Piezodorus guildinii (Westwood). Phylogenetic analysis of the Bloc intergenic region showed that the isolates clustered with Beauveria bassiana reference sequences retrieved from GenBank. The abundance of B. bassiana was significantly higher in agroecological fields than in conventional systems, and in cultivated areas compared with field margins. Isolates Bb-4 SOM, Bb-5 SOM, and Bb-6 SOM caused the fastest decline in survival probability, the greatest sporulation rates (83.8%), and showed the shortest LT₅₀ (5.09–5.17 days) and LC50 values (7.96 × 10⁴–9.7 1.04 × 10⁵ conidia mL−¹), whereas Bb-61 SCM and Bb-63 SCM exhibited intermediate survival and virulence values. In contrast, Bb-18 showed a slower reduction in survival probability, displayed reduced sporulation (45.0%), the longest LT₅₀ (7.49 days), and the highest LC₅₀ value (5.0 × 10⁶ conidia mL−¹). Overall, agroecological fields yielded a higher recovery of native B. bassiana isolates, and selected isolates recovered from these fields exhibited greater virulence under laboratory conditions against P. guildinii. These findings highlight the potential of native isolates as candidates for sustainable biological control programs.