Symbiont-mediated protection varies with wasp genotype in the Drosophila melanogaster–Spiroplasma interaction
Symbiont-mediated protection varies with wasp genotype in the Drosophila melanogaster–Spiroplasma interaction
复制标题
果蝇-螺原体相互作用中共生体介导的保护随黄蜂基因型的不同而变化
作者：
J. Jones;G. Hurst
昆虫抵抗天敌攻击的能力可以通过防御性共生体的存在来调节。蚜虫-共生体-天敌相互作用的研究表明，保护可能取决于共生体，寄主和攻击寄生虫基因型的相互作用。然而，这些相互作用的重要性是知之甚少，这个模型系统之外。在这里，我们研究果蝇模型系统内的相互作用，其中螺原体保护其主机对寄生蜂和线虫。我们研究是否螺原体赋予其主机，果蝇的保护力度不同的攻击Leptopilina heterotoma黄蜂菌株。我们在存在和不存在乙醇的情况下进行这种分析，乙醇是一种环境因素，也会影响寄生的结果。我们观察到螺原体杀死了所有的黄蜂菌株。然而，螺原体产生的保护黄蜂攻击后依赖于黄蜂菌株。保护的综合措施，包括苍蝇存活攻击的机会和幸存者的相对繁殖力/生育力，从Lh 14菌株的黄蜂攻击苍蝇宿主后共生体的<4%的积极作用到不存在乙醇的Lh-Fr菌株的21%。我们还观察到，环境乙醇改变了对黄蜂菌株的保护模式。这些数据表明，螺原体-果蝇-黄蜂三方相互作用的动态依赖于攻击黄蜂种群内的遗传多样性，因此，在自然系统中的共生体动态的预测将需要跨天敌基因型和环境乙醇水平的分析。
The ability of an insect to survive attack by natural enemies can be modulated by the presence of defensive symbionts. Study of aphid–symbiont–enemy interactions has indicated that protection may depend on the interplay of symbiont, host and attacking parasite genotypes. However, the importance of these interactions is poorly understood outside of this model system. Here, we study interactions within a Drosophila model system, in which Spiroplasma protect their host against parasitoid wasps and nematodes. We examine whether the strength of protection conferred by Spiroplasma to its host, Drosophila melanogaster varies with strain of attacking Leptopilina heterotoma wasp. We perform this analysis in the presence and absence of ethanol, an environmental factor that also impacts the outcome of parasitism. We observed that Spiroplasma killed all strains of wasp. However, the protection produced by Spiroplasma following wasp attack depended on wasp strain. A composite measure of protection, including both the chance of the fly surviving attack and the relative fecundity/fertility of the survivors, varied from a <4% positive effect of the symbiont following attack of the fly host by the Lh14 strain of wasp to 21% for the Lh-Fr strain in the absence of ethanol. We also observed that environmental ethanol altered the pattern of protection against wasp strains. These data indicate that the dynamics of the Spiroplasma–Drosophila–wasp tripartite interaction depend upon the genetic diversity within the attacking wasp population, and that prediction of symbiont dynamics in natural systems will thus require analysis across natural enemy genotypes and levels of environmental ethanol.