Insect pest invasions pose a major threat to agriculture, forestry and many natural ecosystems. Thaumastocoris peregrinus is an invasive sap-sucking pest of significant economic importance to Eucalyptus forestry that has recently invaded several countries worldwide. In this study we identify the origin and retrace the invasion history of T. peregrinus. We analysed samples from six locations in Africa, South America and Australia using microsatellites markers and a combination of clustering methods and scenario testing using Approximate Bayesian Clustering. We detected clear genetic substructure differentiating African and South American samples, with representatives of both present in Australia. The Australian population from New South Wales showed substantially higher genetic diversity than the Queensland source, which could indicate that this region could be part of the core range and evolutionary origin of the species. Africa and South America were colonised by independent introductions that occurred more or less concurrently. The study illustrates the impact of the bridgehead effect on global invasions following an outbreak or ‘invasion’ within a city in the native range of the insect.

虫害的入侵对农业，林业和许多自然生态系统构成了重大威胁。Thaumastocoris peregrinus是一种侵害树胶的有害生物，对桉树林业具有重要的经济意义，最近已经入侵了全世界的几个国家。在这项研究中，我们确定起源并追溯百日草的入侵历史。。我们使用微卫星标记分析了非洲，南美和澳大利亚六个地区的样本，并结合了聚类方法和使用近似贝叶斯聚类的场景测试。我们检测到清晰的遗传亚结构，区分了非洲和南美的样本，两者的代表都在澳大利亚。来自新南威尔士州的澳大利亚种群显示出比昆士兰来源更高的遗传多样性，这可能表明该地区可能是该物种核心范围和进化起源的一部分。非洲和南美被或多或少同时发生的独立引进所殖民。这项研究表明，在昆虫原生范围内的城市爆发或“入侵”之后，桥头效应对全球入侵的影响。