Location: Pollinating Insect-Biology, Management, Systematics Research
Project Number: 2080-21000-019-078-I
Project Type: Interagency Reimbursable Agreement
Start Date: Oct 1, 2023
End Date: Jan 30, 2026
Objective:
Bumble bees are critically important pollinators for wild plants and agricultural crop production, but are declining globally. Bumble bee population declines have been attributed to several interacting stressors, including land-use alteration and climate change. Little research has investigated the extent to which these stressors interact to alter bumble bee species distributions, habitat associations, and habitat suitability. Impacts of these stressors are further exacerbated on threatened/endangered species, reducing the species’ ability to secure long-term viability. Therefore, the research aims to 1) evaluate the cumulative effects of climate and landscape structure; 2) assess species distribution and habitat suitability; and 3) conduct targeted surveys in areas with a range of habitat suitability indices for two imperiled species: rusty patched and yellow-banded bumble bees. The research will attain a comprehensive understanding of stressors driving bumble bee population shifts and provide a foundation for reintroducing ex situ colonies as a mitigation effort to establish new populations. This will generate tangible recommendations to inform land management practices, conserve diverse pollinator populations, and increase pollination services for local food production.
Approach:
Objective 1: Evaluate the cumulative effects of climate and landscape structure on two imperiled bumble bee species.
This objective will evaluate the cumulative effects of various bioclimatic variables associated with precipitation and temperature, and landscape metrics (Shannon diversity, patch richness density, contiguity, and interspersion and juxtaposition) on two imperiled species: rusty patched and yellow-banded bumble bees, throughout North America. Based on generalized additive model (GAM) and multivariate regression tree (MRT) model outputs, this objective will identify habitat associations for rusty patched and yellow-banded bumble bees, and identify which climate and landscape factors have the largest impact on their populations. Objective 2: Assess species distribution and habitat suitability for two imperiled bumble bee species based on (a) historic and (b) recent occurrences.
This objective will create species distribution maps, which will be used to detect spatial changes in rusty patched and yellow-banded bumble bee species distributions over the last fifty years. Given their imperiled classification, it is expected that the current distribution maps are more spatially restricted than the historic distribution map. Additionally, areas with high habitat suitability based on bioclimatic and land-use characteristics will be identified using point process models and predicted species intensity mapping. Objective 3: Conduct targeted surveys for two imperiled species in areas with a range of habitat suitability indices.
This objective will verify the validity and accuracy of the point process models though targeted surveys for rusty patched and yellow-banded bumble bees. It is expected that rusty patched and yellow-banded bumble bees will be collected more abundantly at sites with high habitat suitability, and rarely at sites with low habitat suitability. Sites with the greatest fit for rusty patched and yellow-banded bumble bees, individually, will be identified, which can be used to select sites for reintroduction of ex situ colonies in the future. Additionally, bumble bee assemblage composition will be calculated at the targeted survey sites.
