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.

解析外来引入有害生物入侵新区域的定殖过程，对限制其进一步扩散及/或多次引入的风险至关重要。本研究针对专性寄生海岸松的韧皮部介壳虫费氏松干蚧（Matsucoccus feytaudi），解析其入侵历史。该寄主专一性昆虫在其自然分布区内不会造成任何危害，但在1960年代被发现于法国东南部海岸松林中后，便对当地森林造成了毁灭性破坏，此后该虫陆续扩散至意大利与科西嘉岛。本研究采用种群遗传学研究方法，基于微卫星标记（microsatellite markers）与近似贝叶斯计算（Approximate Bayesian Computation）推导该种群的近期演化历史。研究结果与此前的线粒体数据（mitochondrial data）一致，证实其自然分布区具有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介壳虫有限的扩散能力。研究结果表明，该虫的入侵历史可分为三个连续阶段，各阶段涉及不同的定殖与扩散过程：20世纪中期，该虫从法国朗德人工林大规模传入法国东南部，这大概率与第二次世界大战后携带有虫的木材运输有关；随后，符合自然扩散模式的跳板扩散（stepping-stone expansion）过程使得费氏松干蚧抵达意大利利古里亚与托斯卡纳地区的海岸松林区；科西嘉岛于1990年代被偶然定殖，最合理的传播路径是从法国东南部及利古里亚的林区引入了有限数量的迁移个体，这与该区域春季盛行风介导的空中扩散（aerial dispersal）模式相符。