Function of <i>SfDNAJA1</i> and <i>SfHSP68</i> in Temperature Stress Response and Apoptosis in Fall Armyworm (<i>Spodoptera frugiperda</i>)

The fall armyworm (<i>Spodoptera frugiperda</i>) is a major invasive pest. To explore its adaptive mechanisms under temperature stress, we conducted transcriptome analysis across six developmental stages and both sexes at 0, 26, and 46 °C. High-temperature stress induced more differentially expressed genes (DEGs, 8,703) than low-temperature stress (5,426), with fourth instar larvae showing the most DEGs at low temperatures. Sex-specific responses were also evident. Sixteen heat shock protein (HSP) genes and 31 apoptosis-related genes were identified as key stress-responsive factors. RNAi knockdown of <i>SfDNAJA1</i> and <i>SfHSP68</i> reduced survival under temperature stress, increased ROS and Cyt <i>c</i> levels, and upregulated apoptosis-related genes, while ATP levels decreased. Elevated caspase-3, G6PD, and GST activities further indicated oxidative and apoptotic responses. These results underscore the essential role of HSPs in maintaining cellular homeostasis and regulating apoptosis during thermal stress, offering insights into pest adaptation and potential control strategies.