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A rapidly warming climate is driving changes in biodiversity worldwide, and its impact on insect communities is critical given their outsized role in ecosystem function and services. We use a long‐term dataset of North American bumble bee species occurrences to determine whether the community temperature index (CTI), a measure of the balance of warm‐ and cool‐adapted species in a community, has increased given warming temperatures. CTI has increased by an average of 0.99°C in strong association with warming maximum summer temperatures over the last 30 years with the areas exhibiting the largest increases including mid‐ to high latitudes as well as low and high elevations—areas relatively shielded from other intensive global changes. CTI shifts have been driven by the decline of cold‐adapted species and increases in warm‐adapted species within bumble bee communities. Our results show the pervasive impacts and ecological implications warming temperatures pose to insects. [ABSTRACT FROM AUTHOR]

Heatwaves are an increasingly common extreme weather event across the globe and are projected to surge in frequency and severity in the coming decades. Plant‐pollinator mutualisms are vulnerable due to interacting effects of extreme heat on insect pollinator foraging behaviour and their forage plants.We designed an experiment to parse the impact of extreme heat on bumblebee foraging mediated directly through air temperature and indirectly through changes in plant rewards.Temperatures simulating a moderate heatwave negatively impacted foraging bumblebees reducing the proportion of successful foraging bouts, foraging bout duration and plant and flower visitation and indirect stress through reduced nectar production that limited foraging bout duration.Our experimental results provide a mechanistic link between climate, plants and pollinators and suggest in situ conditions from heatwaves could have profound negative consequences for bumblebee colony persistence and maintenance of pollination services. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Declines of many bumble bee species have raised concerns because of their importance as pollinators and potential harbingers of declines among other insect taxa. At present, bumble bee conservation is predominantly focused on midsummer flower restoration in open habitats. However, a growing body of evidence suggests that forests may play an important role in bumble bee life history. Compared with open habitats, forests and woody edges provide food resources during phenologically distinct periods, are often preferred nesting and overwintering habitats, and can offer favorable abiotic conditions in a changing climate. Future research efforts are needed in order to anticipate how ongoing changes in forests, such as overbrowsing by deer, plant invasions, and shifting canopy demographics, affect the suitability of these habitats for bumble bees. Forested habitats are increasingly appreciated in the life cycles of many bumble bees, and they deserve greater attention from those who wish to understand bumble bee populations and aid in their conservation. [ABSTRACT FROM AUTHOR]