Data from: Loss of reproductive parasitism following transfer of male-killing Wolbachia to Drosophila melanogaster and Drosophila simulans

Wolbachia manipulates insect host biology through a variety of means that result in elevated fitness of infected females, enhancing its own transmission. A Wolbachia strain (wInn) naturally infecting D. innubila induces male-killing, while native strains of D. melanogaster and D. simulans usually induce cytoplasmic incompatibility (CI). In this study, we transferred wInn to D. melanogaster and D. simulans by embryonic microinjection, expecting conservation of the male-killing phenotype to the novel hosts, which are more suitable for genetic analysis. In contrast to our expectations, there was no effect on offspring sex ratio. Furthermore, no CI was observed in the transinfected flies. Overall, transinfected D. melanogaster lines displayed lower transmission rate and lower densities of Wolbachia than transinfected D. simulans lines, in which established infections were transmitted with near-perfect fidelity. In D. simulans, strain wInn had no effect on fecundity and egg to adult development. Surprisingly, one of the two transinfected lines tested showed increased longevity. We discuss our results in the context of host-symbiont co-evolution and the potential of symbionts to invade novel host species.

沃尔巴克氏体（Wolbachia）可通过多种途径调控昆虫宿主的生物学特性，以提升感染该菌的雌性宿主的适合度，进而增强自身的传播效率。天然感染Innubila果蝇（Drosophila innubila）的沃尔巴克氏体菌株wInn会诱导杀雄表型，而黑腹果蝇（Drosophila melanogaster）与拟果蝇（Drosophila simulans）的本土沃尔巴克氏体菌株通常会诱导细胞质不相容（cytoplasmic incompatibility, CI）。本研究通过胚胎显微注射（embryonic microinjection）技术，将wInn菌株转入黑腹果蝇与拟果蝇体内，预期该杀雄表型可在这两种更适用于遗传分析的新宿主中得以保留。但与预期相悖的是，wInn并未对子代性别比例产生任何影响。此外，在跨宿主感染的果蝇中未观察到细胞质不相容现象。总体而言，黑腹果蝇的跨感染株系展现出较拟果蝇跨感染株系更低的沃尔巴克氏体传播率与菌体密度；而拟果蝇的跨感染株系中，建立的沃尔巴克氏体感染可实现近乎完美的保真传递。在拟果蝇体内，wInn菌株对宿主繁殖力以及卵至成虫的发育过程均无影响。令人意外的是，本次测试的两株跨感染株系中有一株表现出寿命延长的表型。本研究结合宿主-共生菌共进化的研究视角，以及共生菌入侵新型宿主物种的潜在可能性，对上述实验结果展开了讨论。