BACKGROUND Wolbachia, one of the most abundant taxa of intracellular Alphaproteobacteria, is widespread among arthropods and filarial nematodes. The presence of these maternally inherited bacteria is associated with modifications of host fitness, including a variety of reproductive abnormalities, such as cytoplasmic incompatibility, thelytokous parthenogenesis, host feminization and male-killing. Wolbachia has attracted much interest for its role in biological, ecological and evolutionary processes as well as for its potential use in novel and environmentally-friendly strategies for the control of insect pests and disease vectors including a major agricultural pest, the South American fruit fly, Anastrepha fraterculus Wiedemann (Diptera: Tephritidae). RESULTS We used wsp, 16S rRNA and a multilocus sequence typing (MLST) scheme including gatB, coxA, hcpA, fbpA, and ftsZ genes to detect and characterize the Wolbachia infection in laboratory strains and wild populations of A. fraterculus from Argentina. Wolbachia was found in all A. fraterculus individuals studied. Nucleotide sequences analysis of wsp gene allowed the identification of two Wolbachia nucleotide variants (named wAfraCast1_A and wAfraCast2_A). After the analysis of 76 individuals, a high prevalence of the wAfraCast2_A variant was found both, in laboratory (82%) and wild populations (95%). MLST analysis identified both Wolbachia genetic variants as sequence type 13. Phylogenetic analysis of concatenated MLST datasets clustered wAfraCast1/2_A in the supergroup A. Paired-crossing experiments among single infected laboratory strains showed a phenotype specifically associated to wAfraCast1_A that includes slight detrimental effects on larval survival, a female-biased sex ratio; suggesting the induction of male-killing phenomena, and a decreased proportion of females producing descendants that appears attributable to the lack of sperm in their spermathecae. CONCLUSIONS We detected and characterized at the molecular level two wsp gene sequence variants of Wolbachia both in laboratory and wild populations of A. fraterculus sp.1 from Argentina. Crossing experiments on singly-infected A. fraterculus strains showed evidence of a male killing-like mechanism potentially associated to the wAfraCast1_A - A. fraterculus interactions. Further mating experiments including antibiotic treatments and the analysis of early and late immature stages of descendants will contribute to our understanding of the phenotypes elicited by the Wolbachia variant wAfraCast1_A in A. fraterculus sp.1.

中文翻译：

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阿根廷Anastrepha fraterculus sp1种群中的Wolbachia感染：两种菌株之一引起的性别比畸变的初步证据。

背景技术Wolbachia是细胞内Alteproteobacteria细菌中最丰富的一种，在节肢动物和丝状线虫中很普遍。这些母体遗传细菌的存在与宿主适应性的改变有关，包括各种生殖异常，例如细胞质不相容，单壁单性生殖，宿主女性化和雄性杀死。沃尔巴契亚州因其在生物，生态和进化过程中的作用以及其在控制害虫和病媒（包括主要的农业害虫，南美果蝇）等新型和环境友好战略中的潜在用途而引起了人们的极大兴趣。 ast（Anastrepha fraterculus）维德曼（Diedera ：:科）。结果我们使用了wsp，16S rRNA和多基因座序列分型（MLST）方案，包括gatB，coxA，hcpA，fbpA和ftsZ基因来检测和表征来自阿根廷的fraterculus实验室菌株和野生种群中的Wolbachia感染。在所有研究的A. fraterculus个体中都发现了Wolbachia。wsp基因的核苷酸序列分析可以鉴定出两个Wolbachia核苷酸变体（分别名为wAfraCast1_A和wAfraCast2_A）。在分析了76位个体之后，在实验室（82％）和野生种群（95％）中都发现了wAfraCast2_A变体的高患病率。MLST分析将Wolbachia的两个遗传变异都确定为序列类型13。对超级组A中的wAfraCast1 / 2_A进行聚类的串联MLST数据集的系统发育分析。单个受感染实验室菌株之间的配对杂交实验显示了一种与wAfraCast1_A特别相关的表型，包括对幼虫存活的轻微有害影响，即女性偏向性别比。提示诱发了男性杀戮现象，而产生后代的雌性比例下降，这似乎是由于其精子细胞中缺乏精子所致。结论我们在分子水平上检测和鉴定了来自阿根廷的A. fraterculus sp.1的实验室和野生种群中Wolbachia的两个wsp基因序列变体。对单个感染的黄曲霉菌株进行的交叉实验表明，存在一种可能与wAfraCast1_A-黄曲霉相互作用潜在相关的雄性杀人样机制的证据。