Zhu Wei, Zhang Huan, Meng Qian, Wang Menglong, Zhou Guiling, Li Xuan, Wang Hongtuo, Miao Lin, Qin Qilian, Zhang Jihong
State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; Department of Herpetology, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041.
State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
J Insect Physiol. 2017 Jul;100:53-64. doi: 10.1016/j.jinsphys.2017.05.008. Epub 2017 May 18.
The common cutworm, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae), is a destructive pest in Asia. Although overwintering in the field has not been reported for this species, their larvae are capable of long-term survival in fluctuating temperatures, i.e., 5°C (12h) plus 13°C (12h), if food is available. With an increase in climate change due to global warming and the widespread use of greenhouses, further understanding of their cold survival strategy is needed to predict and control their population in the future. In this study, metabolomics was performed to analyze the metabolic features of S. litura larvae exposed to two typical low temperatures: 15°C and 4°C, at which the development, locomotion and feeding activities are maintained or halted, respectively. The results showed that the strategies that regulate lipid and amino acid metabolism were similar at 15°C and 4°C. Cold exposure induced a metabolic shift of energy from carbohydrate to lipid and decreased free amino acids level. Biosynthesis likely contributed to the decrease in amino acids levels even at 4°C, a non-feeding temperature, suggesting an insufficient suppression of anabolism. This explains why food and high temperature pulses are necessary for their long-term cold survival. Glycometabolism was different between 15°C and 4°C. Carbohydrates were used rapidly at 15°C, while trehalose accumulated at 4°C. Interestingly, abundant trehalose and serine are prominent features of Spodoptera exigua larvae, an overwintering species, when compared to S. litura larvae. Exposure to 4°C also induced up-regulation of carbohydrase and protease in the guts of S. litura. Therefore, it is likely that concurrence of food supplement and fluctuating temperatures could facilitate the cold survival of S. litura larvae. We also found that exposure to 4°C could activate the mevalonate pathway in S. litura larvae, which might be related to glycometabolism at 4°C. Overall, our study describes systematically the responses of a cold susceptible insect, S. litura, to low temperatures and explains how fluctuating temperatures facilitate their long-term cold survival indicating the possibility for overwintering of S. litura larvae with global warming and agricultural reforms.
斜纹夜蛾，Spodoptera litura（Fabricius）（鳞翅目：夜蛾科），是亚洲一种具有破坏性的害虫。尽管尚未有该物种在田间越冬的报道，但如果有食物，其幼虫能够在波动温度下长期存活，即5°C（12小时）加13°C（12小时）。随着全球变暖导致气候变化加剧以及温室的广泛使用，需要进一步了解它们的耐寒生存策略，以便预测和控制其未来种群数量。在本研究中，进行了代谢组学分析，以研究斜纹夜蛾幼虫在两种典型低温（15°C和4°C）下的代谢特征，在这两种温度下，其发育、运动和取食活动分别维持或停止。结果表明，在15°C和4°C下调节脂质和氨基酸代谢的策略相似。低温暴露诱导了能量代谢从碳水化合物向脂质的转变，并降低了游离氨基酸水平。即使在4°C（非取食温度）下，生物合成可能也导致了氨基酸水平的下降，这表明合成代谢的抑制不足。这解释了为什么食物和高温脉冲对它们的长期耐寒生存是必要的。15°C和4°C下的糖代谢有所不同。在15°C时碳水化合物迅速被利用，而在4°C时海藻糖积累。有趣的是，与斜纹夜蛾幼虫相比，越冬物种甜菜夜蛾幼虫的显著特征是含有丰富的海藻糖和丝氨酸。暴露于4°C还会诱导斜纹夜蛾肠道中碳水化合物酶和蛋白酶的上调。因此，食物补充和温度波动的同时出现可能有助于斜纹夜蛾幼虫的耐寒生存。我们还发现，暴露于4°C可激活斜纹夜蛾幼虫的甲羟戊酸途径，这可能与4°C下的糖代谢有关。总体而言，我们的研究系统地描述了对低温敏感的昆虫斜纹夜蛾的反应，并解释了温度波动如何促进其长期耐寒生存，这表明随着全球变暖和农业改革，斜纹夜蛾幼虫有可能越冬。
