Interactions between pollinators and plants can be affected by presence of plant pathogens that substitute their infectious propagules for pollen in flowers and rely on pollinators for transmission to new hosts. However, it is largely unknown how pollinators integrate cues from diseased plants such as altered floral rewards and floral traits, and how their behavior changes afterwards. Understanding pollinator responses to diseased plants is crucial for predicting both pathogen transmission and pollen dispersal in diseased plant populations. In this study, we investigated pollinator responses to contact with plants of Dianthus carthusianorum diseased with anther smut (Microbotryum carthusianorum). We combined three approaches: 1) observation of individual pollinators foraging in experimental arrays of pre-grown potted plants; 2) measurements of floral rewards and floral traits of healthy and diseased plants; and 3) quantification of pollen/spore loads of pollinator functional groups. We found that pollinators showed only weak preferences for visiting healthy over diseased plants, but after landing on plants, they probed fewer flowers on the diseased ones. Since diseased flowers offered lower nectar and no pollen rewards, this behavior is consistent with the prediction of optimal foraging models that pollinators should spend less time exploring less rewarding patches or plants. Furthermore, pollen-foraging solitary bees and hoverflies responded to diseased plants more negatively than nectar-feeding butterflies did. Lastly, based on group-specific behavior and typical pollen/spore loads, we suggest that solitary bees and hoverflies contribute to both pollen and pathogen spore dispersal mainly over short distances, while butterfly visits are most important for long-distance dispersal.

中文翻译：

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传粉者调整其行为以适应植物种群中传粉者传播的病原体的存在

传粉媒介和植物之间的相互作用可能会受到植物病原体的影响，这些病原体用它们的传染性繁殖体代替花中的花粉，并依靠传粉媒介传播给新的宿主。然而，授粉者如何整合来自患病植物的线索（例如改变的花奖励和花性状），以及它们之后的行为如何变化，这在很大程度上是未知的。了解传粉媒介对患病植物的反应对于预测病原体传播和花粉在患病植物种群中的传播至关重要。在这项研究中，我们调查了传粉媒介对接触染有花药黑穗病的红花石竹 (Microbotryum carthusianorum) 植物的反应。我们结合了三种方法：1）观察个体授粉者在预先种植的盆栽植物实验阵列中觅食；2) 测量健康和患病植物的花奖励和花性状；3) 传粉媒介官能团的花粉/孢子负荷的量化。我们发现传粉者只对访问健康植物而不是患病植物表现出较弱的偏好，但在降落植物后，它们在患病植物上探查的花朵较少。由于病花提供的花蜜较少且没有花粉奖励，因此这种行为与最佳觅食模型的预测一致，即传粉者应该花更少的时间探索奖励较少的斑块或植物。此外，花粉觅食的独居蜜蜂和食蚜蝇对患病植物的反应比采食花蜜的蝴蝶更消极。最后，基于特定群体的行为和典型的花粉/孢子负载，