A Question of synchrony: Phenological cuing in Lathyrus littoralis and one of its important pollinators, Habropoda miserabilis

Background/Question/Methods

The phenology of plants and their pollinators has become an important conservation concern in the light of climate change. Plants and insects often rely on abiotic cues in their environment as signals for blooming and emerging from their nests, respectively. As abiotic factors like temperature and moisture are altered, species-specific shifts in phenology may occur, which may lead to phenological mismatch between plants and their pollinators. In this study I characterize the blooming phenology of Lathyrus littoralis (Fabaceae) and the flight season phenology of one of its main pollinators, the solitary ground nesting bee Habropoda miserabilis (Apidae), in coastal Northwestern California. Both species are present early in the season, and L. littoralisis is dependent on pollinator visitation for fruit set.  I took advantage of spatial variation in phenology timing to develop models that predict flowering and bee activity as a function of abiotic variables.

Results/Conclusions

Results show that both species are responding to degree-day accumulation, but are responding differently. The best model for predicting bee emergence was based on temperature accumulation at 25cm depth in the soil profile, while the best model for predicting blooming was based on temperature accumulation at the soil surface. To extend this research, a protocol for monitoring H. miserabilis was established for the National Phenology Network. This study and citizen science monitoring program provide insight on the factors that influence the phenology of coastal dune plant species and ground nesting bees. To our knowledge, this is the first study to characterize the flight phenology and predict cues for solitary ground nesting bees at the nest site.