Genome-wide SNPs of vegetable leafminer, : Insights into the recent Australian invasion.

, the vegetable leafminer, is an important agricultural pest originally from the Americas, which has now colonized all continents except Antarctica. In 2015, arrived on the Australian mainland and established on the Cape York Peninsula in the northeast of the country near the Torres Strait, which provides a possible pathway for pests to enter Australia and evade biosecurity efforts. Here, we assessed genetic variation in based on genome-wide single nucleotide polymorphisms (SNPs) generated by double digest restriction-site-associated DNA sequencing (ddRAD-seq), aiming to uncover the potential origin(s) of this pest in Australia and contribute to reconstructing its global invasion history. Our fineRADstructure results and principal component analysis suggest Australian mainland populations were genetically close to populations from the Torres Strait, whereas populations from Asia, Africa, and Papua New Guinea (PNG) were more distantly related. Hawaiian populations were genetically distinct from all other populations of included in our study. Admixture analyses further revealed that from the Torres Strait may have genetic variation originating from multiple sources including Indonesia and PNG, and which has now spread to the Australian mainland. The lineages from Asia and Africa appear closely related. Isolation-by-distance (IBD) was found at a broad global scale, but not within small regions, suggesting that human-mediated factors likely contribute to the local spread of this pest. Overall, our findings suggest that an exotic pest invaded Australia through the Indo-Papuan conduit, highlighting the importance of biosecurity programs aimed at restricting the movement of pests and diseases through this corridor.