## 3 Results
### Comparison of the Main Differential Metabolic Responses  
Through a detailed analysis of the affected metabolites and their associated pathways, we aim to understand the differential metabolic responses of _B. dorsalis_ larvae under various treatments, including IR-alone, HY, Sup-HY, HY + IR, and Sup-HY + IR.  
Based on the KEGG database, we constructed a metabolic pathway network, highlighting the interconnections among the aforementioned five core metabolic pathways and their key compounds, as illustrated in Figure 9A,B. These pathways reveal the primary metabolic variations and shared responses of _B. dorsalis_ larvae under diverse treatment conditions. Notably, the levels of tetradecanoic acid, n-hexadecanoic acid, octadecanoic acid, and oleic acid were significantly reduced in all IR-treated groups. These fatty acids are essential components of several metabolic pathways, including the biosynthesis of unsaturated fatty acids, fatty acid biosynthesis, fatty acid elongation, and fatty acid degradation. This significant decrease can be attributed to the surge in ROS production induced by IR treatment, resulting in localized mitochondrial autophagy [25]. Consequently, mitochondrial energy metabolism is inhibited, prompting the swift oxidation of fatty acids into acetyl-CoA that subsequently enters the TCA cycle for energy generation.  
In both hypoxic treatment groups, HY and Sup-HY, there was a notable decrease in n-hexadecanoic acid levels and a corresponding increase in octadecanoic acid levels. This pattern suggests the activation of both the fatty acid degradation and fatty acid elongation metabolic pathways. The presence of oleic acid suggested the activation of the biosynthesis of unsaturated fatty acids pathway. However, there was no significant difference in oleic acid concentration compared to the control group. The likely cause of this observation is the activation of Hypoxia-Inducible Factor-1 (HIF-1) in both the hypoxic and super-hypoxic conditions. The activation of HIF-1 boosts the expression of antioxidative enzymes, thereby regulating ROS levels within the organism [26]. Consequently, oleic acid experiences reduced oxidative stress, diminishing the formation of lipid peroxides.  
Regarding the IR treatment under the HY and Sup-HY conditions, certain fatty acid levels decreased compared to other groups, presumably because of the combined effects of low-oxygen and IR. The notable reduction in tetradecanoic acid and n-hexadecanoic acid levels indicates a gradual shift in the _B. dorsalis_ larvae's primary energy metabolism from carbohydrates to lipids for efficient ATP production. This metabolic shift typically indicates that the organism is exploiting its \"energy reserves\" to achieve a temporary stress-adaptive capacity under adverse conditions. Consequently, we hypothesize that the fatty acid metabolism might be a crucial pathway for the _B. dorsalis_ larvae to initiate their antioxidative defense mechanism, assisting in the clearance of ROSs induced by IR and reducing their IR sensitivity. Notably, this antioxidative effect appears to amplify as the oxygen concentration decreases, as evidenced by the results in Section 3.1. This observation offers a persuasive explanation for the developmental experiments of the _B. dorsalis_ in our study. While the precise mechanism behind such radioprotective effects remains a 'black-box', our findings could offer a valuable reference for subsequent research.  
The observed alteration in the squalene concentration is noteworthy, given its apparent sensitivity to both low-oxygen and IR conditions. In biological systems, squalene is recognized for augmenting the activity of superoxide dismutase (SOD) [27]. Consequently, elevated squalene levels might correlate with the impact of hypoxia and irradiation on ROS concentrations in _B. dorsalis_ larvae.