Native and managed bees play pivotal roles in maintaining agricultural and wild plant communities. However, some bee populations are declining, likely due in part to climatic and landscape level changes such as urbanization. Here, we used bycatch collected as part of the Cooperative Agricultural Pest Survey Program to gain new insights into how bumble bee populations respond to environmental changes. Our objective was to investigate the extent to which the interaction of landscape composition and abiotic factors impact bumble bee (Hymenoptera: Apidae: Bombus) species in Utah agroecosystems. Specifically, we evaluated bumble bee species’ responses to land cover types (i.e. proportion of urban, agricultural, and non-crop lands) at three spatial scales (1, 3, and 5 km), and interannual variation in temperature, precipitation, and relative humidity from 2014 to 2018. We used a canonical correspondence analysis to evaluate the correlations between our explanatory variables: landscape composition and abiotic factors, and bumble bee species.
Results/Conclusions
We collected 2,787 bumble bees representing 16 species across five cropping seasons. Bumble bee diversity in Utah was best explained by non-crop vs. urban habitats, temperature, and relative humidity. There were five ubiquitous species throughout the landscape that comprised the bulk of diversity observed across our 16 captured species. Species diversity was higher in high humidity, low temperature, and non-crop dominated habitats than low humidity, high temperature, and urban dominated habitats with a change in species richness from 8 to 3 species, respectively. As Utah becomes warmer and more arid, species correlated with low temperatures and high relative humidity may be more at risk. Meanwhile, ubiquitous species or species associated with higher proportions of urban environments, low relative humidity, and high temperatures may be more resilient given current trends in environmental change. Therefore, species diversity may decrease over time with resilient species becoming more prevalent within the environment. This study identifies species and habitats that may be at risk, such as Bombus morrisoni within high humidity habitats, which can be used to inform future management and land-use planning strategies. Additionally, this study adds to the overall narrative that environmental factors and changing landscapes can impact pollinator biodiversity.