Data from: Transmission and temporal dynamics of anther-smut disease (Microbotryum) on alpine carnation (Dianthus pavonius)

1. Theory has shown that sterilizing diseases with frequency-dependent transmission (characteristics shared by many sexually transmitted diseases) can drive host populations to extinction. 2. Anther-smut disease (caused by Microbotryum sp.) has become a model plant pathogen system for studying the dynamics of vector and sexually transmitted diseases: infected individuals are sterilized, producing spores instead of pollen, and the disease is spread between reproductive individuals by insect pollinators. We investigated anther-smut disease in a heavily infected population of Dianthus pavonius (alpine carnation) over an eight-year period to determine disease impacts on host population dynamics. 3. Over the eight years, disease prevalence remained consistently high (>40%) while the host population numbers declined by over 50%. 4. The observed rate of vector transmission to reproductive, adult hosts was inadequate to explain the high disease prevalence. Additional density-dependent aerial transmission to highly susceptible juveniles, indicated from experimental field and greenhouse studies, is likely to play a key role in maintaining the high disease prevalence. 5. Epidemiological models that accounted for the mixed transmission mode predicted an eventual decline in disease. 6. Synthesis: Our results demonstrate that high prevalence of a sterilizing disease does not necessarily drive host populations towards extinction and also highlights the importance of demographic studies for establishing the presence of alternative transmission modes.1. 已有理论研究表明，带有频率依赖传播（frequency-dependent transmission）特征的绝育型病害（这类特征在多数性传播疾病中均有体现）可导致宿主种群走向灭绝。 2. 花药黑粉病（anther-smut disease，由黑粉菌属物种Microbotryum sp.引发）已成为研究媒介传播与性传播疾病动态的植物病原模式系统：受感染的宿主个体将被绝育，不再产生花粉转而生成孢子，且病害通过昆虫传粉者在繁殖个体间扩散。本研究针对一个重度感染花药黑粉病的高山石竹（Dianthus pavonius, alpine carnation）种群开展了为期8年的跟踪调查，以明确该病害对宿主种群动态的影响。 3. 在该8年调查周期内，病害流行率始终维持在较高水平（>40%），而宿主种群数量下降幅度超过50%。 4. 观测到的媒介传播至繁殖期成年宿主的速率，不足以解释如此高的病害流行率。结合田间与温室实验研究结果，额外存在的、针对高度易感宿主幼体的密度依赖型空气传播，可能在维持高病害流行率的过程中发挥关键作用。 5. 纳入混合传播模式的流行病学模型（epidemiological models）预测，病害最终将出现流行率下降的趋势。 6. 综合分析：本研究结果表明，绝育型病害的高流行率未必会导致宿主种群走向灭绝，同时也凸显了开展种群统计研究以确认是否存在替代传播模式的重要性。