Population structure of Drosophila suzukii and signals of multiple invasions to the continental U.S.

Drosophila suzukii, or spotted wing drosophila, is now an established keystone pest in many parts of the world, causing serious agricultural damage to the fruit crop industry. Native to East Asia, D. suzukii infestations have appeared on both East and West Coasts of the United States, occupying a wide range of climates. To efficiently control this pest, knowledge of past migration events, population structure, and genetic diversity is needed. To improve on previous studies examining genetic structure of D. suzukii, we sequenced whole genomes of individual flies collected across the continental U.S., as well as several representative sites in Europe, Brazil, and Asia, to identify hundreds of thousands of genetic markers for analysis. We analyzed these markers to detect population structure, migration events, and estimate genetic diversity and differentiation within and between continents. We observe strong population structure between West and East Coast populations of the U.S., but no evidence of any population structure North to South, suggesting there is no broad-scale adaptations occurring in response to the large differences in regional winter temperatures. We also find evidence of repeated migration events from Asia into North America have provided increased levels of genetic diversity, which does not appear to be the case for Brazil or Europe. This large genomic dataset will spur future research in genomic adaptations underlying D. suzukii pest activity and development of novel control methods for this agricultural pest.拟谷盗（Drosophila suzukii），亦称斑点翅果蝇，现已成为全球多个地区的标志性害虫，对水果作物产业造成了严重的农业损害。原产于东亚，D. suzukii的侵害已蔓延至美国的东、西海岸，覆盖了广泛的气候区域。为了有效控制此害虫，了解过去的迁移事件、种群结构和遗传多样性至关重要。为了改进先前关于D. suzukii遗传结构的研究，我们对来自美国大陆以及欧洲、巴西和亚洲的多个代表性地点收集的单个果蝇的全基因组进行了测序，以识别数十万个用于分析的遗传标记。我们分析了这些标记，以检测种群结构、迁移事件，并估计大陆内部及其之间的遗传多样性和分化。我们观察到美国西海岸和东海岸种群之间存在强烈的种群结构，但在南北方向上没有发现任何种群结构的证据，这表明在应对区域冬季温度的巨大差异时，并未发生广泛的适应性变化。我们还发现，从亚洲到北美洲的重复迁移事件提供了增加的遗传多样性，这似乎并不适用于巴西或欧洲。这一庞大的基因组数据集将激发未来关于D. suzukii害虫活动背后的基因组适应性研究，以及开发针对这一农业害虫的新颖控制方法。