Virulence of entomopathogenic fungi in larvae of Lepidoptera: Noctuidae

Abstract

Currently, agricultural cropping systems have adopted integrated pest management (IPM) as a successful model for pest control. The use of entomopathogenic fungi in IPM has increased because of their great potential for reducing arthropod pest populations without causing harm to human health and ecosystems. Beauveria bassiana and Metarhizium anisopliae stand out among the most used fungi in biological control, with many isolates commercialized worldwide. Helicoverpa armigera is an agriculturally important pest in Brazil and worldwide, causing damage to several crops. In this context, the objective of this study was to evaluate the biological control potential of Beauveria bassiana, Metarhizium anisopliae, and M. rileyi on H. armigera. The results indicated that the entomopathogenic fungi B. bassiana (strain ESALQ PL63), M. anisopliae (strain ESALQ E9), and M. rileyi (strain UFMS 03), applied using different methods (direct application and dry film) and concentrations (1 × 107, 1 × 108, and 1 × 109 conidia mL-1), resulted in low mortality and no virulence in first-, third-, and fifth-instar larvae of H. armigera. The death of all individuals subjected to treatment with B. bassiana (strain ESALQ PL63) was confirmed by conidiogenesis. Considering the importance of H. armigera as an agricultural pest and the biodiversity of entomopathogenic fungi in Brazil, further investigations on the virulence of fungal strains are necessary to improve the integrated management of lepidopteran pests through microbial control, explore the potential of new strains, and understand the relationships between microorganisms and host defense mechanisms.