Population structure of Drosophila suzukii and signals of multiple invasions in the continental United States

Drosophila suzukii, or spotted-wing drosophila, is now an established pest in many parts of the world, causing significant damage to numerous fruit crop industries. Native to East Asia, D. suzukii infestations started in the United States a decade ago, occupying a wide range of climates. To better understand invasion ecology of this pest, knowledge of past migration events, population structure, and genetic diversity is needed. In this study, we sequenced whole genomes of 237 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, to reconstruct migration events, and to estimate genetic diversity and differentiation within and among the continents. We observed strong population structure between West and East Coast populations in the U.S., but no evidence of any population structure North to So...