Data from: Patterns of Widespread Decline in North American Bumble Bees

Bumble bees (Bombus) are vitally important pollinators of wild plants and agricultural crops worldwide. Fragmentary observations, however, have suggested population declines in several North American species. Despite rising concern over these observations in the United States, highlighted in a recent National Academy of Sciences report, a national assessment of the geographic scope and possible causal factors of bumble bee decline is lacking. Here, we report results of a 3-y interdisciplinary study of changing distributions, population genetic structure, and levels of pathogen infection in bumble bee populations across the United States. We compare current and historical distributions of eight species, compiling a database of >73,000 museum records for comparison with data from intensive nationwide surveys of >16,000 specimens. We show that the relative abundances of four species have declined by up to 96% and that their surveyed geographic ranges have contracted by 23–87%, some within the last 20 y. We also show that declining populations have significantly higher infection levels of the microsporidian pathogen Nosema bombi and lower genetic diversity compared with co-occurring populations of the stable (nondeclining) species. Higher pathogen prevalence and reduced genetic diversity are, thus, realistic predictors of these alarming patterns of decline in North America, although cause and effect remain uncertain.
Bumble bees (Bombus) are integral wild pollinators within native plant communities throughout temperate ecosystems, and recent domestication has boosted their economic importance in crop pollination to a level surpassed only by the honey bee. Their robust size, long tongues, and buzz-pollination behavior (high-frequency buzzing to release pollen from flowers) significantly increase the efficiency of pollen transfer in multibillion dollar crops such as tomatoes and berries. Disturbing reports of bumble bee population declines in Europe have recently spilled over into North America, fueling environmental and economic concerns of global decline. However, the evidence for large-scale range reductions across North America is lacking. Many reports of decline are unpublished, and the few published studies are limited to independent local surveys in northern California/southern Oregon, Ontario, Canada, and Illinois.
Furthermore, causal factors leading to the alleged decline of bumble bee populations in North America remain speculative. One compelling but untested hypothesis for the cause of decline in the United States entails the spread of a putatively introduced pathogen, Nosema bombi, which is an obligate intracellular microsporidian parasite found commonly in bumble bees throughout Europe but largely unstudied in North America. Pathogenic effects of N. bombi may vary depending on the host species and reproductive caste and include reductions in colony growth and individual life span and fitness. Population genetic factors could also play a role in Bombus population decline. For instance, small effective population sizes and reduced gene flow among fragmented habitats can result in losses of genetic diversity with negative consequences, and the detrimental impacts of these genetic factors can be especially intensified in bees. Population genetic studies of Bombus are rare worldwide. A single study in the United States identified lower genetic diversity and elevated genetic differentiation (FST) among Illinois populations of the putatively declining B. pensylvanicus relative to those of a codistributed stable species. Similar patterns have been observed in comparative studies of some European species, but most investigations have been geographically restricted and based on limited sampling within and among populations.
Although the investigations to date have provided important information on the increasing rarity of some bumble bee species in local populations, the different survey protocols and limited geographic scope of these studies cannot fully capture the general patterns necessary to evaluate the underlying processes or overall gravity of declines. Furthermore, valid tests of the N. bombi hypothesis and its risk to populations across North America call for data on its geographic distribution and infection prevalence among species. Likewise, testing the general importance of population genetic factors in bumble bee decline requires genetic comparisons derived from sampling of multiple stable and declining populations on a large geographic scale. From such range-wide comparisons, we provide incontrovertible evidence that multiple Bombus species have experienced sharp population declines at the national level. We also show that declining populations are associated with both high N. bombi infection levels and low genetic diversity.
This data was used in the paper "Patterns of widespread decline in North American bumble bees" published in the Proceedings of the National Academy of United States of America.
For more information about this dataset contact:
Sydney A. Cameron: [e-mail]
James Strange: [e-mail] Resources in this dataset:Resource Title: Data from: Patterns of Widespread Decline in North American Bumble Bees (Data Dictionary). File Name: meta.xmlResource Description: This is an XML data dictionary for Data from: Patterns of Widespread Decline in North American Bumble Bees.Resource Title: Patterns of Widespread Decline in North American Bumble Bees (DWC Archive). File Name: occurrence.csvResource Description: File modified to remove fields with no recorded values.Resource Title: Patterns of Widespread Decline in North American Bumble Bees (DWC Archive). File Name: dwca-usda-ars-patternsofwidespreaddecline-bumblebees-v1.1.zipResource Description: Data from: Patterns of Widespread Decline in North American Bumble Bees -- this is a Darwin Core Archive file.
The Darwin Core Archive is a zip file that contains three documents.

The occurrence data is stored in the occurrence.txt file.
The metadata that describes the columns of this document is called meta.xml. This document is also the data dictionary for this dataset.
The metadata that describes the dataset, including author and contact information for this dataset is called eml.xml.

Find the data files at https://bison.usgs.gov/ipt/resource?r=usda-ars-patternsofwidespreaddecline-bumblebees

Bombus属的蜂类作为全球野生植物和农业作物的关键传粉者，其重要性不言而喻。然而，零散的观察结果表明，北美多个物种的种群数量呈下降趋势。尽管美国国家科学院近期报告中强调了对此现象的关注，但关于大黄蜂种群数量下降的地理范围和可能的原因尚无全国性的评估。在本研究中，我们报告了美国大黄蜂种群分布变化、种群遗传结构和病原体感染水平的三年跨学科研究结果。我们比较了八种大黄蜂的当前和历史分布，并建立了包含超过73,000份博物馆记录的数据库，以与超过16,000个样本的全国性密集调查数据进行比较。我们发现，四种大黄蜂的相对丰度下降了高达96%，其调查的地理分布范围缩小了23-87%，其中一些在过去的20年内已发生显著变化。此外，我们还发现，种群数量下降的种群中，微孢子虫病原体Nosema bombi的感染水平显著升高，与稳定（非下降）物种共存的种群相比，遗传多样性较低。因此，病原体的高检出率和遗传多样性的降低，成为北美大黄蜂种群数量下降的警示性模式的真实预测指标，尽管因果关系尚不明确。

大黄蜂作为温带生态系统原生植物群落中的关键野生传粉者，其经济重要性在作物传粉方面已超越蜜蜂，仅次于家蜂。其健壮的体型、长长的舌部和嗡嗡传粉行为（高频嗡嗡声以释放花中的花粉）显著提高了番茄和浆果等价值数十亿美元的作物中花粉传递的效率。近期关于欧洲大黄蜂种群数量下降的令人不安的报告已蔓延至北美，引发了全球范围内环境和经济上的担忧。然而，北美大规模分布范围缩减的证据仍然不足。许多关于种群数量下降的报告尚未公开发表，而少数已发表的独立地方性调查仅限于加利福尼亚北部/俄勒冈南部、加拿大安大略省和伊利诺伊州。

此外，导致北美大黄蜂种群数量下降的原因仍属推测。一个引人注目但未经检验的假设是，美国大黄蜂种群数量下降的原因可能是一种假定的引入性病原体Nosema bombi的传播，该病原体是一种在欧洲大黄蜂中普遍存在的细胞内寄生物，但在北美却鲜有研究。N. bombi的病原效应可能因宿主物种和生殖群体而异，包括降低蜂群生长速度、缩短个体寿命和降低个体适应性。种群遗传因素也可能在Bombus种群数量下降中发挥作用。例如，有效种群数量较小和破碎生境间的基因流减少可能导致遗传多样性的丧失，这些遗传因素的负面影响在蜜蜂中尤为显著。全球范围内对Bombus的种群遗传学研究极为罕见。美国的一项研究在伊利诺伊州发现了疑似下降的B. pensylvanicus种群相对于共分布的稳定物种，遗传多样性较低和遗传分化（FST）升高。类似的模式在欧洲某些物种的比较研究中也有观察到，但大多数研究在地理上受到限制，且采样范围有限。

尽管迄今为止的研究为某些大黄蜂物种在局部种群中日益稀少提供了重要信息，但这些研究的不同调查协议和有限的地理范围无法充分捕捉评估潜在过程或总体下降严重程度的总体模式。此外，对N. bombi假设及其对北美种群风险的验证需要其地理分布和物种间的感染流行率数据。同样，测试种群遗传因素在大黄蜂种群数量下降中的普遍重要性需要来自多个稳定和下降种群的大规模地理采样中的遗传比较。通过此类范围广泛的比较，我们提供了无可争议的证据，证明多个Bombus物种在全国范围内经历了急剧的种群数量下降。我们还发现，下降的种群与高N. bombi感染水平和低遗传多样性相关。

本数据用于发表在《美国国家科学院院刊》上的论文“North American bumble bees widespread decline patterns”。

有关此数据集的更多信息请联系：Sydney A. Cameron: [e-mail]，James Strange: [e-mail]。

本数据集包含以下资源：
资源标题：Patterns of Widespread Decline in North American Bumble Bees (数据字典)，数据来源：Patterns of Widespread Decline in North American Bumble Bees，文件名：meta.xml，资源描述：这是Patterns of Widespread Decline in North American Bumble Bees的XML数据字典。
资源标题：Patterns of Widespread Decline in North American Bumble Bees (DWC档案)，文件名：occurrence.csv，资源描述：已修改的文件，移除了无记录值的字段。
资源标题：Patterns of Widespread Decline in North American Bumble Bees (DWC档案)，文件名：dwca-usda-ars-patternsofwidespreaddecline-bumblebees-v1.1.zip，资源描述：Patterns of Widespread Decline in North American Bumble Bees的数据，这是一个Darwin Core Archive文件。
Darwin Core Archive是一个包含三个文档的zip文件。
发生数据存储在occurrence.txt文件中。
描述此文档列的元数据称为meta.xml，此文档也是此数据集的数据字典。
描述数据集的元数据，包括此数据集的作者和联系信息，称为eml.xml。
数据文件可在https://bison.usgs.gov/ipt/resource?r=usda-ars-patternsofwidespreaddecline-bumblebees找到。