Pollinator reductions can leave communities less diverse and potentially at increased risk of infectious diseases. Species-rich plant and bee communities have high species turnover, making the study of disease dynamics challenging. To address how temporal dynamics shape parasite prevalence in plant and bee communities, we screened >5,000 bees and flowers over an entire growing season for five common bee microparasites (Nosema ceranae, Nosema bombi, Crithidia bombi, Crithidia expoeki and neogregarines). Over 110 bee species and 89 flower species were screened, revealing that 42% of bee species (12.2% individual bees) and 70% of flower species (8.7% individual flowers) had at least one parasite in or on them, respectively. Some common flowers (for example, Lychnis flos-cuculi) harboured multiple parasite species whilst others (for example, Lythrum salicaria) had few. Significant temporal variation of parasite prevalence in bees was linked to bee diversity, bee and flower abundance and community composition. Specifically, we found that bee communities had the highest prevalence late in the season, when social bees (Bombus spp. and Apis mellifera) were dominant and bee diversity was lowest. Conversely, prevalence on flowers was lowest late in the season when floral abundance was highest. Thus turnover in the bee community impacted community-wide prevalence, and turnover in the plant community impacted when parasite transmission was likely to occur at flowers. These results imply that efforts to improve bee health will benefit from the promotion of high floral numbers to reduce transmission risk, maintaining bee diversity to dilute parasites and monitoring the abundance of dominant competent hosts.

传粉媒介的减少可能会导致社区多样性降低，并可能增加感染传染病的风险。物种丰富的植物和蜜蜂群落的物种更替率很高，这使得疾病动态研究具有挑战性。为了了解时间动态如何影响植物和蜜蜂群落中寄生虫的流行，我们在整个生长季节对超过 5,000 只蜜蜂和花朵进行了五种常见蜜蜂微寄生虫（Nosema ceranae、Nosemaombi、Crithidiaombi、Crithidiaexpoeki和 neogregarines）的筛查。对超过 110 种蜜蜂和 89 种花卉进行了筛查，结果显示，42% 的蜜蜂（12.2% 蜜蜂个体）和 70% 的花卉（8.7% 个体花朵）体内或表面至少有一种寄生虫。一些常见的花卉（例如，Lychnis flos-cuculi）含有多种寄生虫，而其他花卉（例如，千屈菜）则很少。蜜蜂寄生虫流行率的显着时间变化与蜜蜂多样性、蜜蜂和花朵丰度以及群落组成有关。具体来说，我们发现蜜蜂群落在季节后期的流行率最高，此时群居蜜蜂（熊蜂属和意大利蜜蜂）占主导地位，而蜜蜂多样性最低。相反，在花卉丰度最高的季节后期，花卉流行率最低。因此，蜜蜂群落的更替影响了整个社区的流行，而当寄生虫传播可能发生在花朵上时，植物群落的更替也会受到影响。这些结果意味着改善蜜蜂健康的努力将受益于促进高花数以降低传播风险、保持蜜蜂多样性以稀释寄生虫以及监测优势宿主的丰度。