Genomes of Ganaspis near brasiliensis (Hymenoptera: Figitidae)

During the last decade, the spotted-wing drosophila, Drosophila suzukii, has spread from eastern Asia to the Americas, Europe, and Africa. This fly attacks many species of cultivated and wild fruits with soft, thin skins, where its serrated ovipositor allows it to lay eggs in undamaged fruit. Parasitoids from the native range of D. suzukii may provide sustainable management of this highly mobile, polyphagous pest by controlling fly populations at the landscape level. Among these parasitoids, host-specificity testing has revealed a lineage of Ganaspis near brasiliensis more host-specific to D. suzukii than other species. This lineage appears to be a cryptic species near G. brasiliensis. Here we present results on divergence in genomic sequences and reproductive isolation between cryptic species of Ganaspis near brasiliensis. We studied five populations, two from China, two from Japan, and one from Canada, identified as the G1 versus G3 lineages based on differences in COI sequences. We assembled and annotated the genomes of these populations, and analyzed sequence divergence between them. Finally, we report results from crosses to test reproductive compatibility between the G3 lineage from China and the G1 lineage from Japan. The combined evidence of differences in the assemblies and annotations of the G1 and G3 lineages and their reproductive incompatibility shows that they are different species, and that the previous decision to evaluate the lineages separately, and only import and introduce the more specific lineage to North America and Europe, was appropriate.过去十年间，斑翅果蝇（spotted-wing drosophila, *Drosophila suzukii*）已从东亚扩散至美洲、欧洲与非洲。该果蝇可侵害多种栽培及野生软皮薄皮水果，凭借其锯齿状产卵器（serrated ovipositor）能够在未受损的果实内产卵。源自斑翅果蝇原生分布区的寄生蜂（parasitoids），可通过景观尺度上的种群调控为这种高活动性、多食性害虫提供可持续的防治方案。在这类寄生蜂中，寄主专一性测试（host-specificity testing）显示，一类与巴西广腹细蜂（Ganaspis brasiliensis）近缘的类群对斑翅果蝇的寄主专一性优于其他物种，该类群疑似为巴西广腹细蜂的隐存种（cryptic species）。本研究报道了该近缘巴西广腹细蜂隐存种间的基因组序列分化与生殖隔离相关研究结果：我们共纳入5个种群，其中2个采自中国、2个采自日本、1个采自加拿大，并依据COI序列（COI sequences）的差异将其划分为G1与G3两个类群；我们对这些种群的基因组进行了组装与注释，并分析了类群间的序列分化程度；最后，我们通过杂交实验验证了中国G3类群与日本G1类群间的生殖兼容性，并报道了相关实验结果。综合G1与G3类群的基因组组装、注释差异以及二者间的生殖隔离证据，可证实二者为不同物种，此前将两类群分开评估，并仅将寄主专一性更强的类群引入北美与欧洲的决策是合理的。