# Transcriptomic Responses of Sclerodermus alternatusi Yang to Ultraviolet (UV) Stress of Different Wavelengths

## TL;DR

This study explores how a parasitic wasp, Sclerodermus alternatusi, responds to UV stress at the molecular level, revealing key genes and pathways involved in its survival under UV exposure.

## Contribution

The study identifies novel transcriptomic responses of S. alternatusi to UVA and UVC radiation, providing insights into its molecular adaptability to UV stress.

## Key findings

- UVA exposure upregulated genes related to cellular respiration and oxidative phosphorylation.
- UV stress modulates energy metabolism through pathways like oxidative phosphorylation and thermogenesis.
- RT-qPCR validation confirmed the reliability of RNA-Seq data for selected differentially expressed genes.

## Abstract

Ultraviolet (UV) radiation is a significant environmental stressor that exerts profound impacts on insect physiology, behaviour and survival. Although some insects can use UV light for spatial orientation and navigation, it can induce DNA damage, oxidative stress, and impair critical biological functions, ultimately reducing ecological fitness. Sclerodermus alternatusi Yang (Hymenoptera: Bethylidae) is a dominant ectoparasitoid of the early instar larvae of Monochamus alternatus and plays a key role in the biological control of this pest in forestry systems; however, it faces intense UV exposure in the field environment. Despite its ecological importance, the molecular mechanisms underlying its responses to UV-induced stress remain poorly understood. In this study, newly emerged adult wasps (within 24 h post-eclosion) were exposed to UVA (365 nm) and UVC (253.7 nm) radiation for 9 h under controlled laboratory conditions. Total RNA was extracted from treated and control individuals for transcriptomic analysis using RNA-Seq. A total of 505 differentially expressed genes (DEGs) were identified; gene ontology enrichment analysis revealed that UVA exposure significantly upregulated genes involved in cellular respiration and oxidative phosphorylation, suggesting an enhanced metabolic response. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that UV stress modulates energy metabolism through the activation of oxidative phosphorylation and thermogenesis-related pathways, highlighting the reallocation of energy resources in response to UV-induced stress. To validate the RNA-Seq data, four representative DEGs were selected for quantitative real-time PCR (RT-qPCR) analysis. The qPCR results were consistent with the transcriptomic trends, confirming the reliability of the sequencing data. Collectively, this study provides a comprehensive overview of the molecular response mechanisms of S. alternatusi to UV stress, offering novel insights into its environmental adaptability and laying a theoretical foundation for its application in biological pest control under field conditions.