Potential of native entomopathogenic fungi isolates against the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) in Maize in Ethiopia

The fall armyworm (Spodoptera frugiperda) invasion poses a significant threat to maize production in Africa. Some entomopathogenic fungal strains, particularly those from the genera Beauveria and Metarhizium, have been considered as potential biological control agents for this pest. When these entomopathogenic fungi are present in fields, they can not only infect individual pests but also spread among pest populations, leading to long-term suppression. In this study, 17 entomopathogenic fungi isolates, including 12 Beauveria spp. and 5 Metarhizium spp., were evaluated under laboratory conditions. Pathogenicity assessments revealed significant variation in mortality rates among the isolates. Specifically, Beauveria isolates APPRC-44BC and APPRC-27 demonstrated high larval mortality rates of 88.7% and 83.5%, respectively. The dose-response study showed that APPRC-44BC had the lowest LC50 (2.8 x 105 conidia/mL) and LC90 (2.2 x 107 conidia/mL) values. Subsequently, the three most pathogenic isolates, two from Beauveria spp. (APPRC-44BC and APPRC-27) and one from Metarhizium sp. (APPRC-34GM), were evaluated under field conditions in maize. Treatments with these isolates, particularly APPRC-44BC, significantly reduced leaf damage and increased yield compared to the negative control. These findings underscore the potential of native entomopathogenic fungi isolates as sustainable alternatives for managing S. frugiperda. The present study addresses a critical knowledge gap in Africa and offers an environmentally friendly alternative to chemical pesticides for effective pest management. Further evaluation of these promising isolates in diverse agroecological settings is needed to confirm their effectiveness across different regions.