## 4 Discussion
Currently, the specific changes in the lipid metabolism within the insects following the IR-alone, HY, Sup-HY, HY + IR and Sup-HY treatments are not fully understood. Therefore, further studies are needed to comprehensively understand the roles of lipid metabolic pathways. Research suggests that diminished metabolic activity can counteract the oxidative stress caused by IR under hypoxic conditions. As previous studies have highlighted, both IR and MA treatments impact the mitochondrial electron transport chain and the TCA cycle [40; 41; 42]. Thus, carbohydrates might have a limited role in the insect energy metabolism post IR and MA treatments. This finding further strengthens the conclusion that lipid metabolic pathways have a significant impact on insects after treatments such as IR-alone, HY, Sup-HY, IR + HY, and IR + Sup-HY. Furthermore, [PERSON] et al. 's research showed that the development of the Mediterranean fruit fly (_Certainis capitata_) is regulated by changes in oxygen consumption rates and the levels of primary energy molecules, such as lipids, glycogen, and trehalose. [PERSON] et al. analyzed the expression patterns and functions of fatty acid synthase genes (_SIFAS1_ and _SIFAS2_) in the larvae of the tobacco cutworm (_Spodorea litura_), demonstrating the crucial role of fatty acid synthesis and storage in insects' metabolism and metamorphic development [43; 44]. These findings support the results observed in this study of the developmental delays in _B. dorsalis_ larvae under hypoxic conditions, as depicted in Figure 2(A(1)-A(3)); the decreased pupation rate and hindered emergence, as shown in Figure 2(B(1)-B(3)), suggest that IR further impairs metabolic activity in insects, thereby hindering their normal development within the expected timeframe. Based on metabolomics, this study provides a preliminary mechanistic explanation for the enhanced tolerance of _B. dorsalis_ larvae to IR under hypoxic stress for the first time. It is well established that the metabolic rate of _B. dorsalis_ larvae significantly decreases in hypoxic conditions [8; 45]. However, under hypoxic conditions, while both the carbohydrate and lipid metabolisms are limited, cells favor the fatty acid metabolism--a more ATP-productive pathway--with the primary source of these fatty acids being the oxidation of intracellular lipid droplets [46; 47; 48]. In the early phases of hypoxic stress, cells quickly amass substantial ROSs, mainly from an overload of electrons in the electron transport chain due to a lack of oxygen [49; 50]. Furthermore, IR not only damages DNA structures but also disrupts the electron transport chain, resulting in substantial ROS production [8; 30; 51]. Excessive ROSs can act as signaling molecules to enhance the activity of antioxidative enzymes, maintaining an ROS balance in organisms [52]. Key factors in the oxygen-sensing pathway, such as HIF-1 and nuclear factor erythroid-derived 2-like 2 (Nrf2), induced and upregulated by hypoxic stress, regulate the gene expression of antioxidative enzymes. This enhances the organism's oxidative resistance, improving stress resistance during development. Specifically, HIF-1 activation inhibits the TCA cycle, increases the production of reducing molecules in organisms, and promotes lipid degradation [53]. Meanwhile, Nrf translocates to the cell nucleus, binding to the antioxidant response element (ARE), thereby activating the expression of antioxidative and detoxifying genes [54]. Moreover, studies have shown that hypoxic stress also can induce mitochondrial autophagy mediated by BNIP3 and FUNDC1, further alleviating oxidative damage caused by ROSs [55; 56]. This study has potential limitations. We evaluated the effects of IR based on observations of naked _B. dorsalis_ larvae, which differs from typical phytosanitary treatments on whole fruits. However, our simplified experimental design ensured each larva received a uniform and precise IR dose, allowing us to directly link metabolic changes to the irradiation treatment.