1. Agricultural intensification leads to wide ranging changes in habitats along with reduction in nesting site availability and flower resources for wild pollinators. Yet, little is known about the impact of these changes on functional traits of communal ground-nesting bees.
2. This study assesses the abundance and body size of a common and widespread North American ground-nesting bee, Agapostemon virescens, throughout three consecutive years at three land use types: (i) unmowed meadows, (ii) conventional pesticide use and mowed agricultural and (iii) organic pesticide-free mowed landscapes.
3. We found no difference in abundance among the three land use types, but body size of spring bees was smaller at farmlands than meadow sites. Body size also varied among years, and bees were smaller in years that followed warm and dry summer seasons. Spring bees were particularly small at organic farms in years following dry and warm summers.
4. Our results suggest that the smaller size of overwintering bees at agricultural lands could compromise their long-term survival. This study indicates that a higher frequency of dry and warm summers as a consequence of climate change can impede bee populations in the future.

中文翻译：

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土地利用类型和季节气候对地面筑巢野蜂的影响

1. 农业集约化导致栖息地的广泛变化，同时减少了野生传粉媒介的筑巢地点和花卉资源。然而，关于这些变化对公共地面筑巢蜜蜂功能特征的影响知之甚少。
2. 本研究评估了一种常见且广泛分布的北美地面筑巢蜂Agapostemon virescens连续三年在三种土地利用类型中的丰度和体型：（i）未割草的草地，（ii）常规杀虫剂的使用和割草的农业和（ iii) 无有机农药修剪过的景观。
3. 我们发现三种土地利用类型之间的丰度没有差异，但农田春季蜜蜂的体型比草地要小。体型也因年份而异，在温暖干燥的夏季之后的年份中，蜜蜂的体型较小。在干燥温暖的夏季之后的几年里，有机农场的春季蜜蜂特别少。
4. 我们的研究结果表明，在农田越冬的蜜蜂规模较小可能会损害它们的长期生存。这项研究表明，由于气候变化，夏季干燥和温暖的频率更高，可能会阻碍未来的蜜蜂种群。