Data from: Contrasted invasion processes imprint the genetic structure of an invasive scale insect across southern Europe

Deciphering the colonization processes by which introduced pests invade new areas is essential to limit the risk of further expansion and/or multiple introductions. We here studied the invasion history of the maritime pine bast scale Matsucoccus feytaudi. This host-specific insect does not cause any damage in its native area, but it devastated maritime pine forests of South-Eastern France where it was detected in the 1960s, and since then reached Italy and Corsica. We used population genetic approaches to infer the populations’ recent evolutionary history from microsatellite markers and Approximate Bayesian Computation. Consistent with previous mitochondrial data, we showed that the native range is geographically strongly structured, which is probably due to the patchy distribution of the obligate host and the limited dispersal capacity of the scale. Our results show that the invasion history can be described in three successive steps involving different colonization and dispersal processes. During the mid-XXth century, massive introductions occurred from the Landes planted forest to South-Eastern France, probably due to transportation of infested wood material after World War II. Stepping-stone expansion, consistent with natural dispersal, then allowed M. feytaudi to reach the maritime pine forests of Liguria and Tuscany in Italy. The island of Corsica was accidentally colonized in the 1990s, and the most plausible scenario involves the introduction of a limited number of migrants from the forests of South-Eastern France and Liguria, which is consistent with an aerial dispersal due to the dominant winds that blow in spring in this region.

解析外来入侵有害生物的定殖扩散过程，是防控其进一步扩张及多次引入风险的核心前提。本研究聚焦海岸松毡蚧（Matsucoccus feytaudi）的入侵历史。该寄主专性昆虫在其自然分布区内不会造成任何危害，但于20世纪60年代在法国东南部被监测到后，对当地海岸松人工林造成了毁灭性破坏，此后其分布范围蔓延至意大利与科西嘉岛。本研究采用群体遗传学方法，基于微卫星标记（microsatellite markers）与近似贝叶斯计算（Approximate Bayesian Computation），推演了该种群近期的演化历史。与此前的线粒体基因组数据结果一致，本研究证实其原生分布区存在显著的地理遗传结构，这一现象大概率源于专性寄主的斑块状分布以及该蚧虫有限的扩散能力。研究结果表明，该物种的入侵过程可分为三个连续阶段，涉及不同的定殖与扩散机制：20世纪中期，该蚧虫从法国朗德省人工林大规模传入法国东南部，这一事件大概率与二战后携带有虫木材的运输活动有关；随后，符合自然扩散模式的跳板式扩散使得该蚧虫得以蔓延至意大利利古里亚与托斯卡纳地区的海岸松松林；科西嘉岛于20世纪90年代意外被该蚧虫定殖，最合理的入侵场景为：少量迁移个体从法国东南部与利古里亚地区的林区传入，这与该区域春季主导风向驱动的空中扩散模式相符。