New Record of Metarhizium brunneum Infecting Banana Weevil in Peru: Implications for Biological Control

The use of entomopathogenic fungi as biological control agents has gained increasing relevance as a sustainable alternative to chemical insecticides in tropical agroecosystems. In this study, a naturally occurring isolate of Metarhizium brunneum infecting adults of Metamasius hemipterus was recovered from banana plantations in the Amazonas region, Peru, and evaluated for its potential as a biological control agent. Multilocus phylogenetic analysis based on tef1α, β-tubulin, rpb1, and rpb2 sequences confirmed its taxonomic identity within the M. brunneum clade. Physiological characterization revealed variability in growth and thermal response among isolates, while conidial production differed significantly depending on the substrate. Notably, isolate PM9 exhibited the highest conidial yield on rice substrate. Pathogenicity assays demonstrated high virulence against adult weevils, with an LC50 of 2.91 × 105 conidia·mL−1 and mortality exceeding 90% at the highest concentration tested. These findings indicate that isolate PM9 combines desirable physiological and pathogenic traits for biological control. The natural occurrence of this entomopathogen in banana systems suggests ecological adaptation to local conditions and supports its potential incorporation into integrated pest management strategies, although further field-based evaluation is required.