Flowering plants require conspecific pollen to reproduce but they often also receive heterospecific pollen, suggesting that pollinators carry mixed pollen loads. However, little is known about drivers of abundance, diversity or composition of pollen carried by pollinators. Are insect-carried pollen loads shaped by pollinator traits, or do they reflect available floral resources? We quantified pollen on 251 individual bees and 95 flies in a florally diverse community. We scored taxonomic order, sex, body size, hairiness and ecological specialization of pollinators, and recorded composition of available flowers. We used phylogenetically controlled model selection to compare relative influences of pollinator traits and floral resources on abundance, diversity and composition of insect-carried pollen. We tested congruence between composition of pollen loads and available flowers. Pollinator size, specialization and type (female bee, male bee, or fly) described pollen abundance, diversity and composition better than floral diversity. Pollen loads varied widely among insects (10–80,000,000 grains, 1–16 species). Pollen loads of male bees were smaller, but vastly more diverse than those of female bees, and equivalent in size but modestly more diverse than those of flies. Pollen load size and diversity were positively correlated with body size but negatively correlated with insect ecological specialization. These traits also drove variation in taxonomic and phylogenetic composition of insect-carried pollen loads, but composition was only weakly congruent with available floral resources. Qualities of pollinators best predict abundance and diversity of carried pollen indicating that functional composition of pollinator communities may be important to structuring heterospecific pollen transfer among plants.

开花植物需要同种花粉才能繁殖，但它们通常还接受异种花粉，这表明传粉者携带的花粉混合。然而，关于授粉媒介所携带的花粉丰度，多样性或组成的驱动因素知之甚少。昆虫携带的花粉是否受传粉者性状的影响，或者它们反映的是可用的花卉资源？在一个花木繁多的社区中，我们对251只蜜蜂和95只苍蝇的花粉进行了定量分析。我们对生物分类学，性别，体型，毛羽和传粉媒介的生态专长进行了评分，并记录了可用花的成分。我们使用系统发育控制的模型选择来比较授粉媒介性状和花卉资源对昆虫携带的花粉的丰度，多样性和组成的相对影响。我们测试了花粉负载量和可用花量之间的一致性。授粉媒介的大小，专长和类型（雌蜂，雄蜂或蝇）描述的花粉丰度，多样性和组成优于花的多样性。昆虫之间的花粉负荷差异很大（10–80,000,000粒，1–16种）。雄蜂的花粉量较小，但比雌蜂的花粉量大得多，大小相等，但比苍蝇的花粉量略多。花粉负载量和多样性与体长成正相关，与昆虫生态专业化成负相关。这些特性也驱使昆虫携带的花粉负荷的分类学和系统发育组成发生变化，但组成与可利用的花卉资源之间的关系很小。