Cold adaptation mechanism in <i>Bactrocera dorsalis</i> (Diptera: Tephritidae) by regulating MAPK signaling and metabolic pathways

Bactrocera dorsalis (Hendel, 1912), a major invasive pest, survives under extreme climates through molecular and tissue-specific cold stress adaptations. In this study, we investigated the tissue-specific impacts of cold stress on the survival and molecular response of B. dorsalis. Results showed that cold stress had a significant effect on survival rates. The Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated that signaling and metabolic pathways were activated by cold stress in the head and fat body during a transcriptome analysis. Under cold stress, 184 and 365 genes were differentially expressed in the head and fat body, respectively. RNA interference (RNAi)-mediated knockdown of transposon Ty3-I Gag-Pol polyprotein (Ty3-I) and Ty3-G Gag-Pol polyprotein (Ty3-G) in the head and fat body, significantly reduced the larval survival. Relative expression analysis revealed that expression of the Ty3-I and Ty3-G Gag-Pol polyprotein was greatly reduced in the head of cold treated larvae relative to controls (dsGFP) and that the expression level of Ty3-I Gag-Pol polyprotein in the fat body was not significantly reduced by cold stress. These results highlight the tissue-specific response of Ty3-I and Ty3-G Gag-Pol polyproteins in mediating cold stress responses and aid in understanding their importance in survival and stress adaptation. Additionally, the identification of important stress-responsive genes provides a foundation for the development of RNAi-based strategies for pest control using the targeted disruption of stress adaptation gene pathways for more effective control of B. dorsalis populations.