Impacts of climate warming on solitary bee and annual wildflower phenology, traits, interactions, and reproduction

Climate warming is expected to lead to widespread species declines, which are particularly concerning for beneficial insects such as bees. Temperature can directly affect bees by altering phenology and decreasing survival and body size. Warming can also impact resource availability for bees such as changes to floral quality and phenology. We have a limited understanding of the ways in which these factors may individually or together influence communities of bees and plants. We investigated the impacts of climate warming on experimental communities of three annual wildflowers and the solitary bee Osmia lignaria. We established three temperature regimes in greenhouses and measured flowering and nesting phenology, traits, interactions, and reproduction. Warmed plant communities produced fewer flowers with less, more concentrated nectar. Bees in warmed treatments initiated nesting earlier, with impacts on bee behavior and plant reproduction. Understanding how bees and plants are impacted directly and indirectly by climate warming is a critical step towards predicting the effects of future warming on populations and communities in both natural and managed systems.