Cell-free supernatant of Entomopathogenic Fungi isolated from infected Spodoptera frugiperda larvae offer superior biocontrol against this species over conidia infection.

Fall armyworm (FAW), Spodoptera frugiperda is a major pest of maize that causes substantial yield losses and necessitates effective and sustainable control strategies. In this study, nine entomopathogenic fungi (EPF) were isolated from naturally infected FAW larvae collected from maize fields in Lampung, Indonesia. Molecular and morphological identification revealed the isolates as Penicillium citrinum, Penicillium expansum, Aspergillus flavus, Cladosporium tenuissimum, Geosmithia pallida, Beauveria bassiana, and Sarocladium zeae. Bioassays demonstrated that S. zeae, P. expansum, and C. tenuissimum exhibited higher pathogenicity against FAW larvae compared to B. bassiana. Notably, this study provides the first report of S. zeae as an entomopathogen of FAW. Although the direct application of conidial suspensions resulted in moderate mortality, the use of crude cell-free supernatant significantly enhanced larval mortality and suppressed feeding activity. The highest bioefficacy was observed for cell-free supernatant derived from S. zeae and C. tenuissimum. Chemical profiling using GC-MS detected a diverse range of bioactive compounds, including fatty acid esters, aldehydes, ketones, and furanone derivatives, which are known to possess insecticidal, antifungal, or growth-inhibitory activities. These results indicate that integrating EPF with their cell-free supernatant can substantially improve biocontrol performance. This dual strategy offers a promising approach for developing environmentally friendly and sustainable management programs for S. frugiperda in maize agroecosystems.