Fachin Ruiz, GreciaCórdova Sinarahua, DeyvisRomero Chávez, Lorena EstefaniAlvarado Ramírez, JaimeQuesquen Lopez, CesarFlores García, EybisKoch Duarte, ChristianCerna Mendoza , AgustínVásquez Bardales, JoelCorazon Guivin, Mike2026-04-062026-04-062026-03-09Fachin-Ruiz, G., Córdova-Sinarahua, D., Romero-Chávez, L. E., Alvarado-Ramírez, J., Quesquen-Lopez, C., Flores-García, E., Koch-Duarte, C., Cerna-Mendoza, A., Vásquez-Bardales, J., & Corazon-Guivin, M. (2026). Native entomopathogenic nematodes from Peru control Spodoptera frugiperda, a major pest of Zea mays in the Peruvian Amazon. International Journal of Molecular Sciences, 27(5), 2502. https://doi.org/10.3390/ijms270525021422-0067http://hdl.handle.net/20.500.12955/3075This study evaluated entomopathogenic nematodes (EPNs) isolated from a cacao agroforestry system in the Peruvian Amazon, focusing on their molecular characterization and efficacy against Spodoptera frugiperda (Lepidoptera: Noctuidae) larvae. Thirteen EPN isolates were obtained from 50 soil samples using the Galleria mellonella baiting technique. Mortality assays revealed significant differences among isolates at 24, 48, and 72 h, with isolates 11N-A4 and 8N-B1 being the most virulent, achieving maximum mortalities of 100% and 96.3% at 72 h, respectively. Median lethal time (LT50) values indicated rapid action of these isolates on G. mellonella larvae, with 33.3 h for 11N-A4 and 32.4 h for 8N-B1. Molecular identification using ITS, D2-D3 (LSU), and COI markers confirmed the isolates as Heterorhabditis sp. (11N-A4) and Heterorhabditis amazonensis (8N-B1). In bioassays with S. frugiperda larvae, both EPNs exhibited dose- and time-dependent mortality. H. amazonensis showed rapid action, reaching 100% mortality at the highest dose (60 IJs/larvae) within 48 h, whereas Heterorhabditis sp. displayed a gradual, sustained increase, attaining 91% mortality at 72 h. Median lethal dose (LD50) and LT50 values reflected the efficiency of both isolates, with Heterorhabditis sp. achieving lower LD50 at later stages and shorter LT50 at low-to-intermediate doses. These findings highlight the potential of Heterorhabditis sp. and H. amazonensis as effective biocontrol agents adapted to local conditions and represent the first report of H. amazonensis in Peru. Further studies under field conditions are required to confirm their suitability for incorporation into integrated pest management strategies in the Peruvian Amazon.application/pdfenginfo:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by/4.0/Median lethal dose LD50Dosis letal mediana DL50Median lethal time LT50Tiempo letal mediano TL50Heterorhabditis amazonensisFall armywormGusano cogolleroPeruvian AmazonAmazonía peruanaEntomopathogenic nematodesNemátodos entomopatógenosBiological controlControl biológicoSpodoptera frugiperdaZea maysMaízMolecular characterizationCaracterización molecularBioassayBioensayoAgroforestryAgroforesteríaCacaoIntegrated pest managementManejo integrado de plagasinfo:eu-repo/semantics/articlehttps://purl.org/pe-repo/ocde/ford#4.04.00https://doi.org/10.3390/ijms27052502Nemátodos entomopatógenos; Entomopathogenic nematodes; Control biológico; Biological control; Gestión de lucha integrada; Integrated pest management; Patogenicidad; Pathogenicity Bioensayos; Bioassays Agroforestería; Agroforestry; Larvas; Larvae Lepidoptera; Theobroma cacao; Theobroma cacao; Plagas de plantas; Plant