BACKGROUND The black soldier fly (Diptera: Stratiomyidae, Hermetia illucens) is renowned for its bioconversion ability of organic matter, and is the worldwide most widely used source of insect protein. Despite varying extensively in morphology, it is widely assumed that all black soldier flies belong to the same species, Hermetia illucens. We here screened about 600 field-collected and cultured flies from 39 countries and six biogeographic regions to test this assumption based on data for three genes (mitochondrial COI, nuclear ITS2 & 28S rDNA) and in order to gain insights into the phylogeography of the species. RESULTS Our study reveals a surprisingly high level of intraspecific genetic diversity for the mitochondrial barcoding gene COI (divergences up to 4.9%). This level of variability is often associated with the presence of multiple species, but tested nuclear markers (ITS2 and 28S rDNA) were invariant and fly strain hybridization experiments under laboratory conditions revealed reproductive compatibility. COI haplotype diversity is not only very high in all biogeographic regions (56 distinct haplotypes in total), but also in breeding facilities and research centers from six continents (10 haplotypes: divergences up to 4.3%). The high genetic diversity in fly-breeding facilities is mostly likely due to many independent acquisitions of cultures via sharing and/or establishing new colonies from field-collected flies. However, explaining some of the observed diversity in several biogeographic regions is difficult given that the origin of the species is considered to be New World (32 distinct haplotypes) and one would expect severely reduced genetic diversity in the putatively non-native populations in the remaining biogeographic regions. However, distinct, private haplotypes are known from the Australasian (N = 1), Oriental (N = 4), and the Eastern Palearctic (N = 4) populations. We reviewed museum specimen records and conclude that the evidence for introductions is strong for the Western Palearctic and Afrotropical regions which lack distinct, private haplotypes. CONCLUSIONS Based on the results of this paper, we urge the black soldier fly community to apply molecular characterization (genotyping) of the fly strains used in artificial fly-breeding and share these data in research publications as well as when sharing cultures. In addition, fast-evolving nuclear markers should be used to reconstruct the recent invasion history of the species.

中文翻译：

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黑色士兵蝇（Hermetia illucens）（商业上最重要的昆虫蛋白种类）的线粒体系统图令人费解。

背景技术黑士兵蝇（Diptera：Stratiomyidae，Hermetia illucens）以其有机物的生物转化能力而闻名，并且是全世界使用最广泛的昆虫蛋白来源。尽管形态上存在很大差异，但人们普遍认为所有黑士兵苍蝇都属于同一物种，即Hermetia illucens。我们在这里筛选了来自39个国家和六个生物地理区域的大约600个野外采集和培养的苍蝇，以基于三个基因（线粒体COI，ITS2和28S rDNA核DNA）的数据来检验该假设，以便深入了解该物种的系统地理学。 。结果我们的研究揭示了线粒体条形码基因COI的种内遗传多样性水平高得惊人（差异高达4.9％）。这种可变性水平通常与多种物种的存在有关，但是测试的核标记（ITS2和28S rDNA）是不变的，在实验室条件下的蝇品系杂交实验显示出繁殖相容性。COI单倍型多样性不仅在所有生物地理区域都很高（总共56种不同的单倍型），而且在六大洲的育种设施和研究中心中也是如此（10个单倍型：差异高达4.3％）。繁殖设施中遗传多样性高的原因很可能是由于许多人通过共享和/或从野外采集的苍蝇建立新的殖民地而独立地获得了文化。然而，鉴于该物种的起源被认为是新大陆（32个不同的单倍型），并且难以预测其余生物地理区域中假定为非本地种群的遗传多样性，因此很难解释几个生物地理区域中观察到的某些多样性。但是，从澳大利亚（N = 1），东方（N = 4）和东部古北纪（N = 4）种群中可以发现独特的私人单倍型。我们回顾了博物馆的标本记录，并得出结论，对于缺乏独特的私人单倍型的西部古北非地区和非洲地区来说，引入的证据是有力的。结论基于本文的结果，我们敦促黑人战士果蝇社区对人工果蝇育种中使用的果蝇菌株进行分子鉴定（基因分型），并在研究出版物中以及在分享文化时共享这些数据。此外，应使用快速发展的核标记物来重建该物种最近的入侵历史。