Comparative Transcriptomics Reveals the Regulatory Mechanisms Underlying the Feeding Preference of Spodoptera frugiperda for Different Host Plants

This study investigated the physiological responses and molecular mechanisms underlying the host preference of the polyphagous fall armyworm (FAW) for maize (preferred), rice (alternative), and cotton (nonpreferred). Life-table analysis confirmed that feeding on cotton plants significantly prolonged larval development and reduced survival rates compared with maize. Integrated midgut transcriptomics and physiological analyses revealed that a cotton diet severely impaired larval development by suppressing crucial detoxification pathways (cytochrome P450, glutathione metabolism), reducing juvenile hormone III levels, inhibiting digestive enzymes, and activating apoptosis-related genes. Concurrently, plant transcriptome profiling demonstrated that cotton activated a robust defense network against FAW feeding, consisting of chemical defenses (GhVSPA and GhTDC), physical barriers (GhFAR3 and GhCYP77A3), and signaling pathway regulators (GhMYC4 and GhWRKY18). By integrating transcriptomics data from both interacting organisms, this study elucidates the molecular basis of cotton resistance to FAW, uncovering candidate genes for breeding insect-resistant crops.