Cryptochrome‐1 regulates the ecdysone titer to influence the emergence rhythm of Bactrocera dorsalis

Abstract BACKGROUND The circadian clock is a crucial regulator of life activities in insects, directly influencing survival competitiveness and population expansion. Cryptochrome‐1 ( Cry1 ), a core circadian clock gene, is functionally diverse in insects. RESULTS Phylogenetic analysis revealed that Bactrocera dorsalis Cry1 ( BdCry1 ) clusters closely with Drosophila melanogaster Cry1 ( DmCry1 ), suggesting potential functional conservation. Subsequent expression profiling demonstrated that BdCry1 exhibited robust circadian oscillations and undergoes significant expression fluctuation near the time of adult eclosion in B. dorsalis . To elucidate the functional role of BdCry1 , we generated a knockout strain ( BdCry1 −/− ) via CRISPR/Cas9‐mediated mutagenesis. BdCry1 −/− flies exhibited delayed eclosion timing and disrupted eclosion rhythmicity. Additionally, qPCR revealed significant changes in the transcriptional expression of key neuropeptide genes, including sNPF , PDF , and PTTH . Circadian monitoring of ecdysone (20E) titers by ELISA demonstrated a loss of rhythmic 20E fluctuations and significantly reduced 20E in BdCry1 −/− pupae compared to those in the wild‐type (WT) controls. Moreover, RNA interference‐mediated knockdown of the ecdysone receptor also disrupted eclosion rhythms in WT, confirming the link between eclosion and 20E signaling. CONCLUSION Our findings uncovered a molecular connection between the circadian clock (via Cry1 ) and 20E signaling in the regulation of eclosion rhythms. These results provide novel insights into the integration of hormonal and circadian systems in insects and identify potential molecular targets for the development of biocontrol strategies. © 2025 Society of Chemical Industry.