X-ray irradiation induces complex and temporally attenuating molecular response in navel orangeworm

The navel orangeworm (NOW) is a key pest of almonds, pistachios, and walnuts across California. Research is presently underway to explore the potential of the sterile insect technique (SIT) for NOW control. In this study, we analyzed the transcriptomic changes in NOW exposed to X-ray radiation to elucidate the molecular response and associated mechanisms. The virgin NOW males were exposed to a dose of 300Gy of X-ray radiation and samples were collected at 6-, 12-, 24-, 48-, and 96-hours post-exposure along with matched controls at each time point. RNA sequencing was carried out and differentially expressed genes were identified between irradiated and control samples at each time point. We found nearly 2,000 genes showing differential expression at 6h post exposure in irradiated NOW. Identity of these genes indicated DNA damage, cellular stress, cell cycle arrest as well as apoptosis regulation responses. Genes related to DNA damage repair showed consistent upregulation across the timepoints. However, general transcriptomic response of irradiated NOW gradually reduced over time as much fewer genes showed differential expression at later time points. Overall, this study provides extensive molecular insights into radiation response of a lepidopteran adult by tracking gene expression changes across time points. Results of this study will support the development of molecular markers to evaluate mating viability of sterile NOW for SIT research.