Tetranychus urticae (Acari: Tetranychidae) is a widely distributed agricultural pest, and it possesses an exceptional capacity to withstand or adapt to short-term heat stress. To investigate the molecular mechanisms underlying this heat tolerance, using both transcriptome and whole-genome data, we identified six distinct POD genes in T. urticae and characterized their physicochemical properties and structural features. Real-time quantitative PCR (RT-qPCR) was utilized to analyze the expression profiles of these genes under short-term heat stress. Our results show that T. urticae mitigates heat-induced oxidative stress through the upregulation of POD gene expression, highlighting the critical role of these genes in the mite’s adaptive response to thermal stress. These findings contribute to a deeper understanding of the molecular pathways that enable T. urticae to survive in fluctuating thermal environments, which is increasingly relevant in the context of global climate change. Furthermore, this study provides a foundation for future research utilizing RNA interference (RNAi) technology to further investigate the functional roles of these POD genes and their potential as targets for pest control strategies.

The facultative endosymbiont Serratia symbiotica significantly influences the ecological fitness of its aphid host. However, the molecular mechanisms by which Serratia affects the host’s symbiotic organ, the bacteriocyte, remain poorly understood. Here, we conducted a comparative transcriptomic analysis of bacteriocytes from Serratia− and Serratia+ pea aphid (Acyrthosiphon pisum) strains. Our analysis revealed that Serratia colonization extensively modulates gene expression within bacteriocytes. Key metabolic pathways were significantly altered: genes involved in ribosomal biogenesis and oxidative phosphorylation were upregulated, while those in fatty acid biosynthesis were downregulated. Furthermore, we observed a complex reshaping of the immune profile, characterized by a broad downregulation of immune recognition and signaling components alongside an upregulation of specific effector genes and antioxidant enzymes. These findings suggest that Serratia induces a state of enhanced anabolic capacity and energy production in bacteriocytes, coupled with strategic reallocation of resources and a finely tuned immune response that balances symbiont tolerance with control. Our RT-qPCR validation confirmed the RNA-seq results, further supporting these results. This study provides the first bacteriocyte-specific transcriptomic resource for the aphid–Serratia interaction system, offering novel insights into the molecular integration of a facultative symbiont into host physiology.