The horn fly, Haematobia irritans irritans, is a hematophagous parasite of livestock distributed throughout Europe, Africa, Asia, and the Americas. Welfare losses on livestock due to horn fly infestation are estimated to cost between USD 1-2.5 billion annually in North America and Brazil. The endosymbiotic bacterium Wolbachia pipientis is a maternally inherited manipulator of reproductive biology in arthropods and naturally infects laboratory colonies of horn flies from Kerrville, USA and Alberta, Canada, but has also been identified in wild-caught samples from Canada, USA, Mexico and Hungary. Re-assembly of PacBio long-read and Illumina genomic DNA libraries from the Kerrville H. i. irritans genome project allowed for a complete and circularised 1.3 Mb Wolbachia genome (wIrr). Annotation of wIrr yielded 1249 coding genes, 34 tRNAs, three rRNAs, and five prophage regions. Comparative genomics and whole genome Bayesian evolutionary analysis of wIrr compared to published Wolbachia genomes suggests that wIrr is most closely related to and diverged from Wolbachia supergroup A strains known to infect Drosophila spp. Whole-genome synteny analyses between wIrr and closely related genomes indicates that wIrr has undergone significant genome rearrangements while maintaining high nucleotide identity. Comparative analysis of the cytoplasmic incompatibility (CI) genes of wIrr suggests two phylogenetically distinct CI loci and acquisition of another CifB homolog from phylogenetically distant supergroup A Wolbachia strains suggesting horizontal acquisition of these loci. The wIrr genome provides a resource for future examination of the impact Wolbachia may have in both biocontrol and potential insecticide resistance of horn flies.

Importance Horn flies, Haematobia irritans irritans, are obligate hematophagous parasites of cattle having significant effects on production and animal welfare. Control of horn flies mainly relies on the use of insecticides, but issues with resistance have increased interest in development of alternative means of control. Wolbachia pipientis is an endosymbiont bacterium known to have a range of effects on host reproduction such as induction of cytoplasmic incompatibility, feminization, male killing, and also impacts on vector transmission. These characteristics of Wolbachia have been exploited in biological control approaches for a range of insect pests. Here we report the assembly and annotation of the circular genome of the Wolbachia strain of the Kerrville, USA horn fly (wIrr). Annotation of wIrr suggests its unique features including the horizontal acquisition of additional transcriptionally active cytoplasmic incompatibility loci. This study will provide the foundation for future Wolbachia-induced biological effect studies for control of horn flies.

角蝇（Haematobia irritans irritans）是分布在欧洲，非洲，亚洲和美洲的家畜的食血性寄生虫。据估计，在北美和巴西，因角蝇引起的牲畜福利损失每年造成的损失在1到25亿美元之间。内生共生细菌Wolbachia pipientis是节肢动物的生殖遗传操纵基因，可自然感染美国克尔维尔和加拿大艾伯塔省的角蝇实验室菌落，但也已在加拿大，美国，墨西哥和匈牙利的野生捕获样品中鉴定出。 。从Kerrville H. i。重新组装PacBio的长读和Illumina基因组DNA文库。irritans基因组计划允许完整且循环的1.3 MbWolbachia基因组（wIrr）。w Irr的注释产生了1249个编码基因，34个tRNA，3个rRNA和5个噬菌体区域。与已发表的Wolbachia基因组相比，W Irr的比较基因组学和全基因组贝叶斯进化分析表明，W Irr与已知感染果蝇属的Wolbachia A群超级菌株最相关，也最有区别。w Irr与密切相关的基因组之间的全基因组同义分析表明，w Irr在保持高核苷酸同一性的同时，经历了重大的基因组重排。小麦胞质不相容（CI）基因的比较分析。w Irr提出了两个系统发育上不同的CI基因座，并从系统发育上较远的A群沃尔巴克氏菌菌株中获得了另一个CifB同源物，表明这些基因座是水平采集的。该W¯¯ IRR基因组提供了影响未来的考试资源沃尔巴克氏体可同时具有生物防治和角蝇的潜在抗药性。

重要的角蝇（Hematobia irritans irritans）是牛的专性血吸虫，对生产和动物福利具有重大影响。防治角蝇主要依靠使用杀虫剂，但抗药性问题已引起人们对替代控制手段发展的兴趣。pipientis Wolbachia pipientis是一种共生内生细菌，已知对宿主繁殖具有多种作用，例如诱导细胞质不相容，女性化，雄性杀死以及对载体传播也有影响。Wolbachia的这些特征已在生物防治方法中用于多种害虫。在这里，我们报告了该环状基因组的装配和注释美国科尔维尔角蝇（wIrr）的Wolbachia菌株。w Irr的注释表明其独特的功能包括水平获取其他转录活性细胞质不相容基因座。这项研究将为未来的沃尔巴克氏菌引起的控制角蝇的生物学效应提供基础。