Regulatory influence of Cotesia ruficrus on the development and nutrient metabolism of Spodoptera frugiperda

Abstract BACKGROUND The fall armyworm (FAW), Spodoptera frugiperda is a notorious invasive pest that poses a serious threat to global agricultural production and food security. In China, Cotesia ruficrus has emerged as a promising indigenous biological control agent for controlling FAW populations. In this study, we conducted a series of comprehensive experiments to explore the effects of C. ruficrus parasitization on the development and nutrient metabolism of FAW larvae. RESULTS Parasitization by C. ruficrus significantly inhibited the development of FAW larvae, and significantly reduced their food intake by more than 60%. Furthermore, the concentrations of carbohydrate and triglyceride increased significantly from the third to the fifth day and from the third to the seventh day after parasitization, respectively. However, both carbohydrate and triglyceride levels subsequently decreased during later stages. Transcriptome analysis showed that there were 2096 differentially expressed genes (DEGs) between parasitized and non‐parasitized FAW larvae. These DEGs were found to be primarily enriched in pathways related to immune response, detoxification, lipid synthesis and metabolism, carbohydrate metabolism, and protein metabolism. CONCLUSION Taken together, these results strongly indicate that C. ruficrus has the ability to modulate the development and nutrient metabolism of FAW larvae, ultimately benefiting successful development of the parasitoid offspring. These findings contribute to our understanding of the intricate interactions between host insects and their natural enemies and provide valuable insights into the development of sustainable and effective strategies for FAW control. © 2025 Society of Chemical Industry.