Agricultural practices and intensification during the past two centuries have dramatically altered the abundance and temporal continuity of floral resources that support pollinating insects such as bumble bees. Long-term trends among bumble bees within agricultural regions suggest that intensive agricultural conditions have created inhospitable conditions for some species, while other species have maintained their relative abundances despite landscape-level changes in flower availability. Bumble bee responses to spatiotemporal resource heterogeneity have been explored at the colony and behavioral level, but we have yet to understand whether these conditions drive community structure and ultimately explain the diverging patterns in long-term species trends. To explore the relationship between landscape-level floral resource continuity and the likelihood of bumble bee occurrence, we mapped the relative spatial and temporal availability of floral resources within an intensive agricultural region in the US Upper Midwest and related this resource availability with bumble bee species relative abundance. Across the bee community, we found that relative bumble bee occurrence increases in landscapes containing more abundant and more temporally continuous floral resources. Declining species, such as Bombus terricola, exhibited the strongest, positive responses to resource abundance and continuity whereas common, stable species, such as Bombus impatiens, showed no statistical relationship to either. Together with existing experimental evidence, this work suggests that efforts to increase spatiotemporal flower availability, along with overall flower abundance at landscape scales may have positive effects on bumble bee communities in the US Upper Midwest.

中文翻译：

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景观规模的花卉资源不连续性减少了大黄蜂的出现并改变了群落组成

过去两个世纪的农业实践和集约化极大地改变了支持熊蜂等授粉昆虫的花卉资源的丰度和时间连续性。农业地区熊蜂的长期趋势表明，集约化农业条件为某些物种创造了不适宜生存的条件，而其他物种尽管花卉可用性发生了景观水平的变化，但仍保持了相对丰度。熊蜂对时空资源异质性的反应已经在群体和行为层面上进行了探索，但我们尚未了解这些条件是否会驱动群落结构并最终解释长期物种趋势的分歧模式。为了探索景观水平花卉资源连续性与熊蜂出现可能性之间的关系，我们绘制了美国中西部北部集约农业地区花卉资源的相对空间和时间可用性，并将这种资源可用性与熊蜂物种相对数联系起来。丰富。在整个蜜蜂群落中，我们发现在含有更丰富且时间上更连续的花卉资源的景观中，大黄蜂的出现相对增加。减少的物种，如Bombus terricola，对资源丰富性和连续性表现出最强、积极的反应，而常见、稳定的物种，如Bombus impatiens，与这两者都没有显示出统计关系。结合现有的实验证据，这项工作表明，增加时空花卉可用性以及景观尺度上花卉总体丰度的努力可能会对美国中西部北部的熊蜂群落产生积极影响。