Tomato spotted wilt virus exploits Halloween genes to accelerate development of Frankliniella occidentalis

BACKGROUND: Viruses and their insect vectors have evolved intricate co-evolutionary mechanisms to enhance transmission efficiency. This study aimed to investigate the impact of tomato spotted wilt virus (TSWV) infection on the development of Frankliniella occidentalis, with particular emphasis on the potential involvement of Halloween genes. RESULTS: Genomic analysis identified seven Halloween genes. Transcriptome data from revealed significant upregulation of FoCYP307A1 and FoCYP306A1 during the nymphal and pupal stages in TSWV-infected individuals. These findings were validated by quantitative real-time polymerase chain reaction, which demonstrated a 1.5- to 3-fold increase in transcript levels of these genes during the nymphal, propupal, and pupal developmental stages. TSWV infection significantly shortened the nymphal and pupal developmental durations by 1 day and 0.6 days, respectively. RNA interference (RNAi)-mediated silencing of FoCYP307A1 and FoCYP306A1 significantly prolonged the nymphal and pupal development time, accompanied by a 27.5% and 55% reduction in 20-hydroxyecdysone (20E) levels, respectively. In addition, the transcript levels of 20E key signaling pathway genes, including FoUSP, FoBr-C, FoDHR3, FoE74A, and FoE75, decreased by 16-67%. Importantly, supplementation with 20E effectively reversed the developmental delays caused by RNAi-induced silencing of FoCYP307A1 and FoCYP306A1. Collectively, these results suggest that FoCYP307A1 and FoCYP306A1 play a critical role in mediating TSWV-facilitated development in thrips. CONCLUSION: These findings provide valuable insights into how TSWV exploits ecdysone biosynthesis to accelerate development in insect vectors, offering important implications for integrated pest and disease management strategies. © 2026 Society of Chemical Industry.