Comparative Effects of Different Food Sources on Fitness and Larval Midgut Gene Expression Profiles in Spodoptera...

The fall armyworm, Spodoptera frugiperda, is a highly polyphagous pest threatening global agriculture, with over 353 host plants identified. However, its performance on many hosts remains poorly understood. This study aimed to determine whether S. frugiperda larvae can successfully develop on banana and sweet potato and what transcriptional mechanisms underlie such host adaptation. To address this question, we documented life cycle parameters and compared midgut transcriptomic profiles of S. frugiperda fed on maize, banana, sweet potato, and an artificial diet. The pest completed development on all diets, though growth and development varied. Comparative transcriptomics of larval midguts revealed 630, 3182, and 5083 differentially expressed genes (DEGs) in response to artificial diet, banana, and sweet potato, respectively, relative to maize. Notably, the substantially higher number of DEGs in banana and sweet potato groups compared to the artificial diet indicates that both plant diets impose greater transcriptional demands, likely due to host plant secondary metabolites. GO and KEGG enrichment analyses found that these DEGs were significantly enriched in metabolism terms and detoxification pathways, suggesting that transcriptional reprogramming of detoxification and digestive processes underlies host plant adaptation in S. frugiperda. These results confirm that S. frugiperda larvae can transcriptionally adapt to banana and sweet potato, suggesting that these crops may support larval development and should therefore be considered in risk assessment and monitoring efforts. Our findings provide foundational insights into the molecular mechanisms underlying host adaptability in S. frugiperda.