Data from: Interactions among symbionts operate across scales to influence parasite epidemics

Parasite epidemics may be influenced by interactions among symbionts, which can depend on past events at multiple spatial scales. Within host individuals, interactions can depend on the sequence in which symbionts infect a host, generating priority effects. Across host individuals, interactions can depend on parasite phenology. To test the roles of parasite interactions and phenology in epidemics, we embedded multiple cohorts of sentinel plants, grown from seeds with and without a vertically transmitted symbiont, into a wild host population, and tracked foliar infections caused by three common fungal parasites. Within hosts, parasite growth was influenced by coinfections, but coinfections were often prevented by priority effects among symbionts. Across hosts, parasite phenology altered host susceptibility to secondary infections, symbiont interactions and ultimately the magnitude of parasite epidemics. Together, these results indicate that parasite phenology can influence parasite epidemics by altering the sequence of infection and interactions among symbionts within host individuals.寄生虫流行病的流行可受共生体间相互作用的调控，而此类相互作用依赖于多空间尺度下的既往侵染事件。在宿主个体内部，共生体间的相互作用取决于其侵染宿主的先后顺序，由此产生优先效应（priority effects）；在宿主种群层面，此类相互作用则取决于寄生虫的物候。为验证寄生虫相互作用与物候在流行病发生中的作用，本研究将多批次哨兵植物——其种子分别携带或不携带垂直传播共生体——投放至野生宿主种群中，并追踪了3种常见真菌寄生虫引发的叶部侵染情况。实验结果显示，单个宿主内的寄生虫增殖会受共侵染影响，但共生体间的优先效应往往会阻碍共侵染的发生；在宿主种群层面，寄生虫的物候会改变宿主对二次侵染的易感性、共生体间的相互作用，并最终影响寄生虫流行病的流行规模。综合上述结果，本研究表明：寄生虫的物候可通过改变宿主个体内的侵染顺序与共生体间的相互作用，进而调控寄生虫流行病的发生与发展。