Male killing Spiroplasma protects Drosophila melanogaster against two parasitoid wasps

Maternally transmitted associations between endosymbiotic bacteria and insects are diverse and widespread in nature. Owing to imperfect vertical transmission, many heritable microbes have evolved compensational mechanisms to enhance their persistence in host lineages, such as manipulating host reproduction and conferring fitness benefits to host. Symbiont-mediated defense against natural enemies of hosts is increasingly recognized as an important mechanism by which endosymbionts enhance host fitness. Members of the genus Spiroplasma associated with distantly related Drosophila hosts are known to engage in either reproductive parasitism (i.e., male killing) or defense against natural enemies (the parasitic wasp Leptopilina heterotoma and a nematode). A male-killing strain of Spiroplasma (strain Melanogaster Sex Ratio Organism (MSRO)) co-occurs with Wolbachia (strain wMel) in certain wild populations of the model organism Drosophila melanogaster. We examined the effects of Spiroplasma MSR...自然界中，母系传播的内共生细菌（endosymbiotic bacteria）与昆虫之间的共生关联多样且广泛存在。由于垂直传播存在不完全性，诸多可遗传微生物演化出补偿机制以提升自身在宿主谱系中的存续能力，例如操纵宿主生殖过程、为宿主赋予适合度益处。共生菌介导的宿主抵御自然天敌的能力，正日益被学界认定为内共生菌提升宿主适合度的重要机制。已有研究证实，与亲缘关系较远的果蝇属（Drosophila）宿主相关的螺原体属（Spiroplasma）类群，可发挥生殖寄生（即雄性致死）或抵御自然天敌的功能，其抵御的天敌涵盖寄生蜂异足细蜂（Leptopilina heterotoma）与一种线虫。在模式生物黑腹果蝇（Drosophila melanogaster）的部分野生种群中，同时共存有雄性致死型螺原体菌株（黑腹果蝇性别比例有机体（MSRO），即strain Melanogaster Sex Ratio Organism (MSRO)）与沃尔巴克氏体（Wolbachia）菌株wMel。本研究探究了螺原体MSR……的相关效应。