Along with agricultural intensification, urbanization is often implicated in bee declines worldwide. While the vast majority of studies investigate how bee assemblages respond to urbanization across different spatial scales, very few attempts have used a temporal comparison to evaluate the impact of urbanization. The city of Curitiba in southern Brazil is unique for having long-term data of bees, and thus is a good model for studying urban temporal changes. The main goal of this study is to investigate how a ground-nesting assemblage responded to six decades of urban growth in Curitiba. In this time lapse the city population grew from 140 thousand to almost 2 million inhabitants. We demonstrate a 94% decline in nest abundance, a 35% decline in species richness, and a 24% decline in phylogenetic diversity from 1955 (T1) to 2018 (T2). Temporal beta diversity values between T1 and T2 were very high and most sampling sites were dominated by losses in nest abundance. All sampling sites changed similarly with losses in nesting substrates (i.e. exposed soil) and a substantial increase in surrounding impervious surface. This study exhibits how depletion of nesting substrates combined with increases in urban cover can affect pollinators, a concerning scenario as most bees nest in friable soil and thus are strongly susceptible to urbanization. We emphasize that urban planning policies to protect ground-nesting bees are essential to preserve the important ecological service of pollination in cities.

随着农业集约化，城市化通常与全世界的蜜蜂数量下降有关。尽管绝大多数研究调查了蜂群如何在不同空间尺度上响应城市化，但很少有尝试使用时间比较来评估城市化的影响。巴西南部的库里蒂巴市因拥有蜜蜂的长期数据而独树一帜，因此是研究城市时空变化的良好模型。这项研究的主要目的是调查一个地面嵌套的组合如何响应库里提巴六十年的城市发展。在这段时间里，城市人口从14万增加到近200万。从1955年（T1）到2018年（T2），我们证明巢巢数量下降了94％，物种丰富度下降了35％，系统发育多样性下降了24％。T1和T2之间的时间β多样性值非常高，大多数采样位点以巢巢丰度的损失为主导。所有采样点的变化都类似，巢穴基质（即裸露的土壤）的损失和周围不透水表面的大量增加。这项研究表明，筑巢底物的枯竭加上城市覆盖率的增加如何影响授粉媒介，这是一个令人担忧的情况，因为大多数蜜蜂都在易碎的土壤中筑巢，因此很容易受到城市化的影响。我们强调，保护地面嵌套蜜蜂的城市规划政策对于维护城市授粉的重要生态服务至关重要。e。裸露的土壤）和周围不透水表面的大量增加。这项研究表明，筑巢底物的枯竭加上城市覆盖率的增加如何影响授粉媒介，这是一个令人担忧的情况，因为大多数蜜蜂都在易碎的土壤中筑巢，因此很容易受到城市化的影响。我们强调，保护地面嵌套蜜蜂的城市规划政策对于维护城市授粉的重要生态服务至关重要。e。裸露的土壤）和周围不透水表面的大量增加。这项研究表明，筑巢底物的枯竭加上城市覆盖率的增加如何影响授粉媒介，这是一个令人担忧的情况，因为大多数蜜蜂都在易碎的土壤中筑巢，因此很容易受到城市化的影响。我们强调，保护地面嵌套蜜蜂的城市规划政策对于维护城市授粉的重要生态服务至关重要。