Wolbachia are widespread endosymbionts that affect arthropod reproduction and fitness. Mostly maternally inherited, Wolbachia are occasionally transferred horizontally. Previously, two Wolbachia strains were reported at low prevalence and titres across seven Australian tephritid species, possibly indicative of frequent horizontal transfer. Here, we performed whole-genome sequencing of field-caught Wolbachia-positive flies. Unexpectedly, we found complete mitogenomes of an endoparasitic strepsipteran, Dipterophagus daci, suggesting that Wolbachia in the flies are linked to concealed parasitization. We performed the first genetic characterization of D. daci and detected D. daci in Wolbachia-positive flies not visibly parasitized, and most but not all Wolbachia-negative flies were D. daci-negative, presumably reflecting polymorphism for the Wolbachia infections in D. daci. We dissected D. daci from stylopized flies and confirmed that Wolbachia infects D. daci, but also found Wolbachia in stylopized fly tissues, likely somatic, horizontally transferred, non-heritable infections. Furthermore, no Wolbachia cif and wmk genes were detected and very low mitogenomic variation in D. daci across its distribution. Therefore, Wolbachia may influence host fitness without reproductive manipulation. Our study of 13 tephritid species highlights that concealed early stages of strepsipteran parasitization led to the previous incorrect assignment of Wolbachia co-infections to tephritid species, obscuring ecological studies of this common endosymbiont and its horizontal transmission by parasitoids.

中文翻译：

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宿主-内寄生-内共生关系：隐藏的链翅目为澳大利亚实蝇中的沃尔巴克氏体提供了新的转折

沃尔巴克氏体是影响节肢动物繁殖和健康的广泛内共生菌。大多数是母系遗传，沃尔巴克氏体偶尔会水平转移。此前，据报道，两种Wolbachia菌株在七个澳大利亚 tephritid 物种中的流行率和滴度均较低，这可能表明频繁的水平转移。在这里，我们对野外捕获的Wolbachia阳性果蝇进行了全基因组测序。出乎意料的是，我们发现了内寄生链翅目双翅目 daci 的完整有丝分裂基因组，这表明果蝇中的Wolbachia与隐蔽寄生有关。我们对D. daci进行了第一次遗传表征并检测到Wolbachia阳性果蝇中的D. daci没有明显寄生，大多数但不是所有Wolbachia阴性果蝇都是D. daci阴性的，可能反映了D. daci中Wolbachia感染的多态性。我们从程式化的苍蝇中解剖了D. daci并证实了Wolbachia感染了D. daci，但还在程式化的苍蝇组织中发现了Wolbachia，可能是体细胞的、水平转移的、非遗传性感染。此外，没有检测到Wolbachia cif和wmk基因，并且在D. daci中的有丝分裂基因组变异非常低在其分布范围内。因此，沃尔巴克氏体可能会在没有生殖操纵的情况下影响宿主的适应性。我们对 13 种 tephritid 物种的研究强调，隐藏链球菌寄生的早期阶段导致之前将Wolbachia共感染错误地分配给 tephritid 物种，从而掩盖了对这种常见内共生体的生态学研究及其通过寄生蜂的水平传播。