Functional traits have been shown to be a good predictor of pollen load for some pollinator bee species, but little is known about solitary bees. In this study, I used two solitary oil-collecting bees to explore the impact of functional traits on the pollen load of two oil-secreting Calceolaria species. I therefore measured the visitation frequency, the time spent manipulating the flower, pollinator body size and pollen load for each bee species. The results reveal that each pollinator visits different Calceolaria species (C. cavanillesii and C. filicaulis) for pollen and/or oil and at least another four herb species for pollen in different proportions. In addition, each bee species presents different functional traits that affect Calceolaria pollen load. For C. chilensis, it was only its body size that affected the Calceolaria pollen load, while in C. subcaeruleus, both body size and handling time together account for its pollen load. Overall, these results highlight the role of pollinators’ functional traits in different stages of the pollination process, and even more in specialized plant-pollination systems.

中文翻译：

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不同授粉媒介的功能特征可以解释两只孤独吸油蜂的花粉负荷

对于某些授粉蜂物种，功能性状已被证明可以很好地预测花粉负载，但对单居蜂知之甚少。在这项研究中，我使用了两只孤立的集油蜜蜂来研究功能性状对两种分泌油的山孢属物种花粉含量的影响。因此，我测量了每种蜜蜂的探访频率，操纵花的时间，传粉者的体型和花粉量。结果表明，每个传粉者都以不同的比例访问不同的Calceolaria物种（C. cavanillesii和C. filicaulis）的花粉和/或油，以及至少另外四个草本物种的花粉。此外，每种蜂种都表现出不同的功能特性，这些特性会影响Calceolaria花粉负载。对于C. chilensis的，这只是它的身体大小影响了蒲包花粉负载，而在C. subcaeruleus，两者的机身尺寸和处理时间加起来占了花粉负载。总体而言，这些结果突出了授粉者功能性状在授粉过程不同阶段的作用，甚至在专门的植物授粉系统中也发挥了作用。