The rice striped stem borer (SSB), Chilo suppressalis Walker, and the rice yellow stem borer (YSB), Scirpophaga incertulas Walker, are two of the most damaging pests of rice plant, whose relative crop damage has changed in recent years. Here, we carried out experiments and surveys to understand the potential impact of field flooding on populations of these species. YSB had a consistently higher mortality rate than SSB in overwintering populations. We show that SSB survived under submersion better than YSB, crawled more strongly than YSB, and escaped more effectively from a waterlogged environment than YSB. These differences may relate partly to the longer abdominal prolegs and thoracic legs of SSB than YSB. These factors likely explain why YSB has a higher mortality rate than SSB in overwintering populations and why the relative importance of YSB is declining in some areas. In addition, the flooding method provides an effective cultural practice for some crops. Our results uncover the reasons why flooding practice is more effective for YSB than SSB. The results also point to an effective control measure for YSB.

水稻二化螟（SSB），二化螟沃克和稻三化螟（YSB），三化螟沃克（Walker）是水稻植物中最具破坏性的两种害虫，近年来其相对作物危害发生了变化。在这里，我们进行了实验和调查，以了解田间洪水对这些物种种群的潜在影响。在越冬人群中，YSB的死亡率一直高于SSB。我们显示，SSB在淹没环境下的生存能力比YSB好，比YSB的爬行能力更强，并且比YSB更有效地从淹水环境中逃脱。这些差异可能部分与SSB的腹部前腿和胸部腿比YSB长有关。这些因素可能解释了为什么在越冬人群中YSB的死亡率高于SSB，以及为什么YSB的相对重要性在某些地区正在下降。另外，水淹法为某些农作物提供了有效的养殖实践。我们的结果揭示了淹水实践对YSB比SSB更有效的原因。结果还指出了对YSB的有效控制措施。