Ageing plasticity represents the flexibility of the ageing process in response to non-genetic factors, occurring commonly in animals. However, the regulatory mechanisms underlying ageing plasticity are largely unclear. The density-dependent polyphenism of locusts, Locusta migratoria, displays dramatic lifespan divergence between solitary and gregarious phases, providing a useful system for studying ageing plasticity. Here, we found that gregarious locusts displayed faster locomotor deficits and increased muscle degeneration on ageing than solitary locusts. Comparative transcriptome analysis in flight muscles revealed significant differences in transcriptional patterns on ageing between two phases. RNA interference screening showed that the knockdown of the upregulated PLIN2 gene significantly relieved the ageing-related flight impairments in gregarious locusts. Mechanistically, the gradual upregulation of PLIN2 could induce the accumulation of ectopic lipid droplets and triacylglycerols in flight muscles during the ageing process. Further experiments suggested that ectopic lipid accumulation led to an ageing-related β-oxidation decline through limiting fatty acid transport and content. These findings reveal the key roles of lipid metabolism in the differences of muscle ageing between solitary and gregarious locusts and provide a potential mechanism underlying environment-induced muscle ageing plasticity.

衰老可塑性代表了衰老过程对非遗传因素做出反应的灵活性，这在动物中很常见。然而，老化可塑性背后的调节机制在很大程度上尚不清楚。蝗虫Locusta migratoria的密度依赖性多型现象在独居阶段和群居阶段之间显示出显着的寿命差异，为研究衰老可塑性提供了一个有用的系统。在这里，我们发现与群居蝗虫相比，群居蝗虫在衰老过程中表现出更快的运动缺陷和肌肉退化。飞行肌肉的比较转录组分析揭示了两个阶段之间衰老的转录模式存在显着差异。RNA 干扰筛选表明上调的PLIN2的敲低基因显着缓解了群居蝗虫与衰老相关的飞行障碍。从机制上讲， PLIN2的逐渐上调可诱导衰老过程中飞行肌肉中异位脂滴和甘油三酯的积累。进一步的实验表明，异位脂质积累通过限制脂肪酸运输和含量导致与衰老相关的 β-氧化下降。这些发现揭示了脂质代谢在群居蝗虫和群居蝗虫肌肉衰老差异中的关键作用，并提供了环境诱导肌肉衰老可塑性的潜在机制。