How can we conserve bees in anthropogenic landscapes?
Greenspace design and urban bee success
Cities often contain diverse bee assemblages and even rare bee species (Baldock et al. 2015, Sirohi et al. 2015, Turo et al. 2021).
What drives this urban bee diversity? And how can we harness these factors to encourage greater bee success in cities?
To date, we’ve found that a city’s historical and landscape context can dramatically alter its value for bees. In particular, access to larger patches of greenspace seems to be a critical driver of bee biodiversity (Turo et al. 2021), native bee nesting productivity (Turo and Gardiner 2021), and expanded diet breadth (Turo et al. in review). Likewise, local management can impact bee foraging decisions and nesting productivity, with greater larvae abundance occurring in habitats with native plants (Turo and Gardiner 2021).
To monitor urban bee nesting productivity, we placed trap nests in 40+ greenspaces and 9 urban farms in Cleveland, OH. Like other postindustrial legacy cities, Cleveland has abundant vacant land which can facilitate bee conservation.
Trap nests recruit cavity nesting bees, e.g., Osmia spp., Megachile spp., and can reveal bee diversity, nesting, and foraging patterns. By dissecting the nests and examining pollen provisions, we can reconstruct what plants the bees foraged on.
Wild Bee Conservation at the Agri-Forest Interface
Spring-blooming crops, such as blueberry and apple, are typically pollinator limited (Reilly et al. 2020), meaning their yields could be improved through additional visits by wild or managed bees. In the Northeast United States, roughly 2/3 of the spring bees available to pollinate spring crops are associated with forested landscapes (Smith et al. 2021). Yet, we lack evidence-based guidelines for how to manage eastern deciduous forests to support spring-flying bees.
What plants do spring pollinators forage on in their forested source habitats? And how can we translate these foraging records to manage both forested and agricultural landscapes?
This research is underway. So far, we’ve used amplicon sequencing to analyze the pollen loads of 771 spring crop pollinators collected from forests. Preliminary analysis shows that these bees predominately feed on a variety of woody shrubs, trees, and non-native herbaceous plants. Stay tuned as we translate this foraging data into conservation recommendations.
Trees for bees
Our data indicates that wild bees, like this Colletes inaequalis, are foraging on trees more frequently than we previously thought. What remains to be tested is whether this frequency of foraging indicates a preference for tree pollen or whether bee foraging is proportional to the availability of tree pollen in the spring.
Colletes inaequalis on Acer saccharum (C) Max McCarthy PhD student in the Winfree Laboratory