Phosphine is the dominant chemical used in postharvest pest control. Widespread and highly frequent use of phosphine has been selected for pest insects, including Tribolium castaneum, which is highly resistant. Lipid peroxidation and reactive oxygen species (ROS) are two major factors determining phosphine toxicity; however, the mechanisms of production of these two factors in phosphine toxicity are still unknown. Here, we first determined the time course of phosphine-induced lipid peroxidation and ROS production in T. castaneum. Our results showed that lipid peroxidation occurs before ROS in the process of phosphine toxicity, and fumigated beetles with higher resistance levels were associated with weaker activity on lipid peroxidation and ROS. A significant decline in lipid peroxidation was observed in fumigated individuals after knockdown of cytochrome b5 fatty acid desaturase (Cyt-b5-r) via RNA interference (RNAi), indicating that Cyt-b5-r is critical for triggering phosphine-induced lipid peroxidation. Moreover, significant decreases in both ROS and mortality were detected in fumigated T. castaneum adults fed melatonin for 7 days, an inhibitor of lipid peroxidation. Cyt-b5-r RNAi also inhibited ROS production and mortality in phosphine-treated beetles. Meanwhile, a significant decrease in ROS production (68.4%) was detected in dihydrolipoamide dehydrogenase (DLD) knockdown individuals with phenotypes susceptible to phosphine, suggesting that lipid peroxidation initiates ROS with the expression of DLD. However, a significant increase in ROS (122.1%) was detected in the DLD knockdown beetles with strongly resistant phenotypes, indicating that the DLD-involved pathway may not be the only mechanism of ROS generation in phosphine toxicity and the existence of a moonlighting role in downregulating ROS in strongly resistant T. castaneum.

磷化氢是用于采后害虫防治的主要化学物质。磷化氢的广泛和频繁使用已被选择用于害虫，包括具有高度抗性的赤拟谷盗。脂质过氧化和活性氧（ROS）是决定磷化氢毒性的两个主要因素；然而，这两种因素产生磷化氢毒性的机制仍不清楚。在这里，我们首先确定了红栗中磷化氢诱导的脂质过氧化和 ROS 产生的时间过程。我们的研究结果表明，在磷化氢毒性过程中，脂质过氧化先于ROS发生，抵抗水平较高的熏甲虫与脂质过氧化和ROS活性较弱相关。通过 RNA 干扰 (RNAi) 敲低细胞色素b5脂肪酸去饱和酶( Cyt-b5-r )后，在熏蒸个体中观察到脂质过氧化显着下降，表明Cyt-b5-r对于触发磷化氢诱导的脂质过氧化至关重要。此外，在熏蒸的栗色砗磲成虫中，喂食褪黑激素（一种脂质过氧化抑制剂）7天后，活性氧和死亡率均显着降低Cyt-b5-r RNAi 还抑制磷化氢处理的甲虫中 ROS 的产生和死亡率。同时，在对磷化氢敏感表型的二氢硫辛酰胺脱氢酶（ DLD ）敲低个体中检测到ROS产生显着减少（68.4％） ，表明脂质过氧化通过DLD的表达启动ROS 。然而，在具有强抗性表型的DLD敲除甲虫中检测到 ROS 显着增加（122.1％），表明DLD参与途径可能不是磷化氢毒性中 ROS 产生的唯一机制，并且在磷化氢毒性中存在兼职作用。下调强抗性赤霉中的 ROS 。