According to evolutionary theory, sex ratio distortions caused by reproductive parasites such as Wolbachia and Spiroplasma are predicted to be rapidly normalized by the emergence of host nuclear suppressors. However, such processes in the evolutionary arms race are difficult to observe because sex ratio biases will be promptly hidden and become superficially unrecognizable. The evolution of genetic suppressors has been reported in just two insect species so far. In the small brown planthopper, Laodelphax striatellus, female-biases caused by Spiroplasma, which is a ‘late’ male-killer, have been found in some populations. During the continuous rearing of L. striatellus, we noted that a rearing strain had a 1 : 1 sex ratio even though it harboured Spiroplasma. Through introgression crossing experiments with a strain lacking suppressors, we revealed that the L. striatellus strain had the zygotic male-killing suppressor acting as a dominant trait. The male-killing phenotype was hidden by the suppressor even though Spiroplasma retained its male-killing ability. This is the first study to demonstrate the existence of a late male-killing suppressor and its mode of inheritance. Our results, together with those of previous studies, suggest that the inheritance modes of male-killing suppressors are similar regardless of insect order or early or late male killing.

中文翻译：

---

杀手的沉默：在小型棕色飞虱Laodelphax striatellus的饲养品系中发现雄性杀灭抑制作用

根据进化论，由沃尔巴克氏体和螺旋体等生殖寄生虫引起的性别比例扭曲预计会因宿主核抑制因子的出现而迅速正常化。然而，进化军备竞赛中的这种过程很难观察到，因为性别比例偏差会很快被隐藏起来，表面上无法识别。迄今为止，仅在两种昆虫物种中报道了遗传抑制因子的进化。在小型褐飞虱Laodelphax striatellus 中，在一些种群中发现了由螺旋原体引起的雌性偏倚，这是一种“晚期”雄性杀手。在连续饲养 L. striatellus 的过程中，我们注意到饲养菌株具有 1:1 的性别比，即使它含有螺旋体。通过对缺乏抑制因子的菌株进行基因渗入杂交实验，我们发现 L. striatellus 菌株具有作为显性性状的合子雄性杀死抑制因子。尽管螺原体保留了其杀死雄性的能力，但雄性杀死表型被抑制器隐藏了。这是第一项证明存在晚期雄性杀灭抑制因子及其遗传方式的研究。我们的结果与之前的研究结果一起表明，无论昆虫顺序或早期或晚期雄性杀死，雄性杀死抑制因子的遗传模式都是相似的。