DGIMI, Univ Montpellier, INRAE, Montpellier, France.
Sci Rep. 2024 Mar 8;14(1):5696. doi: 10.1038/s41598-024-56301-0.
The fall armyworm (Spodoptera frugiperda) is one of the major pest insects in diverse crop plants, including maize, rice, and cotton. While the fall armyworm is native to North and South America, its invasion was first reported in West Africa in 2016. Since then, this species has rapidly spread across Sub-Saharan Africa, Asia, and Oceania, as well as Egypt and Cyprus. The fall armyworm is composed of two sympatric strains, the corn and rice strains, designated to their preferred host plants, in native areas. It remains surprisingly unclear whether invasive fall armyworms belong to the corn strain, rice strain, or hybrids of the two, despite a large number of population genetics studies. In this study, we performed population genomics analyses using globally collected 116 samples to identify the strains of invasive fall armyworms. We observed that invasive fall armyworms are genomically most similar to the corn strain. The reconstructed phylogenetic tree supports the hypothesis that invasive fall armyworms originated from the corn strain. All genomic loci of invasive populations exhibit higher genetic similarity to the corn strains compared to the rice strains. Furthermore, we found no evidence of gene flow from rice strains to invasive populations at any genomic locus. These results demonstrate that invasive fall armyworms belong to the corn strain. These results suggest that invasive fall armyworms likely have very limited potential to infest rice. Therefore, the management plan should primarily focus on crops preferred by the corn strain.
草地贪夜蛾（Spodoptera frugiperda）是玉米、水稻和棉花等多种作物的主要害虫之一。虽然草地贪夜蛾原产于北美洲和南美洲，但它于 2016 年首次在西非被报道。自那时以来，这种物种已迅速传播到撒哈拉以南非洲、亚洲和大洋洲，以及埃及和塞浦路斯。草地贪夜蛾由两个共生的种群组成，玉米种群和水稻种群，它们分别以其在原生地区的偏好宿主植物来命名。尽管进行了大量的种群遗传学研究，但令人惊讶的是，入侵的草地贪夜蛾属于玉米种群、水稻种群还是两者的杂交种，仍然不清楚。在这项研究中，我们使用全球收集的 116 个样本进行了种群基因组学分析，以确定入侵草地贪夜蛾的种群。我们观察到，入侵的草地贪夜蛾在基因组上与玉米种群最为相似。重建的系统发育树支持了入侵草地贪夜蛾起源于玉米种群的假设。与水稻种群相比，入侵种群的所有基因组位点与玉米种群表现出更高的遗传相似性。此外，我们在任何基因组位点都没有发现来自水稻种群的基因流到入侵种群的证据。这些结果表明，入侵的草地贪夜蛾属于玉米种群。这些结果表明，入侵的草地贪夜蛾可能对水稻的侵害能力非常有限。因此，管理计划应主要侧重于玉米种群偏好的作物。
