Abstract Background Bactrocera dorsalis (Hendel) is a highly destructive agricultural pest in tropical and subtropical regions. Infested areas are typically exposed to intense ultraviolet (UV) light, which can cause serious damage to insects. Extensive research has demonstrated that 6‐4 photolyase ( 6‐4phr ) repairs UV‐induced damage in various organisms. Results In this study, we found that UV‐B stress significantly reduced the hatching, emergence, and adult survival rates of B. dorsalis . Reverse transcription quantitative polymerase chain reaction (RT‐qPCR) analysis showed that B. dorsalis 6‐4 photolyase ( Bd6‐4phr ) exhibited a distinct expression profile: it was most abundant in reproductive tissues, particularly the ovaries; it was notably up‐regulated during key developmental stages; and it increased substantially after short‐term UV‐B stress. CRISPR/Cas9‐generated Bd6‐4phr −/− mutants showed markedly reduced hatching, emergence, and adult survival rates, which demonstrated significantly greater sensitivity to UV‐B stress than wild‐type (WT) individuals. After identical UV‐B exposure, Bd6‐4phr −/− mutants also exhibited higher whole‐body accumulation of 6‐4 pyrimidine‐pyrimidone photoproducts (6‐4PPs). Furthermore, recombinant Bd6‐4phr protein reduced the concentration of 6‐4PPs in vitro , indicating its role in 6‐4PPs elimination in vivo . Lastly, expression of Bd6‐4phr in Escherichia coli enhanced its UV tolerance and photoreactivation capacity, corroborating this enzyme's functional activity. Conclusion In summary, Bd6‐4phr enhances the environmental adaptability of B. dorsalis by mediating UV‐induced DNA damage repair. Specifically, Bd6‐4phr contributes significantly to B. dorsalis ' adaptation to high‐UV environments, which represents a molecular mechanism underlying this pest's exceptional environmental adaptability. Our work reveals new insights into explaining the powerful environmental adaptability of B. dorsalis . © 2026 Society of Chemical Industry.
Wang et al. (Fri,) studied this question.