It is well documented that many bee and plant species have experienced changes in phenology over the past century, but the environmental cues regulating ground-nesting bee phenology are not well understood. The southeastern blueberry bee (Habropoda laboriosa) emerges early in the spring and is thought to be oligolectic on blueberries (Vaccinium spp.) which have an early and relatively short bloom period. These traits make both this bee and its host plant particularly sensitive to climate change including warming spring temperatures. We gathered data across a 100-yr period from natural history museums and herbaria to examine the phenologies of H. laboriosa and seven Vaccinium spp. that overlap geographically with the bee. Additionally, we collected climate data from PRISM for each bee and plant specimen location, including the average temperature and precipitation during the collection month and two preceding months for each location. We found that the phenology of H. laboriosa has advanced over ~100 years, with more rapid advancement above 40° latitude. Four of the seven Vaccinium spp. show no changes in phenology regardless of latitude, while three Vaccinium spp. phenologies are advancing, though not as rapidly as H. laboriosa. Preliminary evidence shows that H. laboriosa phenology is regulated primarily by temperature and precipitation during the month of emergence, with earlier emergence corresponding to warmer temperatures and greater precipitation. Our results suggest differential responses of H. laboriosa and Vaccinium spp. bloom to spring warming and spring precipitation are driving phenological mismatch in this specialized pollination system.
