Promoting Native Bumblebees in Agricultural systems for conservation and ecosystem service

Promoting Native Bumblebees in Agricultural systems for conservation and ecosystem service

Summary

2009 was a very productive year for this project. We were able to meet many of our objectives and begin preparing for the upcoming field season. We were also able to begin some outreach with the Xerces Society. In 2010 we hope to use the results from this project to make recommendations for hedgerow improvements.

Objectives/Performance Targets

During 2009 we were able to accomplish many of our listed objectives:

1) I completed the pollen quantification using a digital particle counter called “Image.”

2) I identified over 60,000 pollen grains to plant species and was able to determine which plants for which bees show a strong preference.

3) By analyzing the pollen grains, we were able to determine which plants are essential to bees based on their protein content.

4) We were able to begin some outreach with the Xerces Society to teach organizations to monitor their hedgerows.

Accomplishments/Milestones

During 2009 we monitored ten sites for Bombus vosnesenskii. When present, bees were caught and had pollen loads removed for analysis. Of the most common plant species found in pollen loads, five were invasive and six were native. This represents less than half of the total diversity of plants found at sites, which suggests bees are choosing specific plants to collect from regardless of abundance. While native pollens were not significantly collected out of proportion to their abundance, invasive pollens were collected at significantly lower proportions than their abundance.

While native species as a whole were not collected out of proportion to their abundance (i.e. collection significantly above or below availability), B. vosnesenskii preferentially collected from Eschscholzia californica, Lotus scoparius and Eriogonum fasciculatum. However, invasive plants were consistently collected below their availability regardless of species. This suggests that B. vosnesenskii does not collect resources simply according to pollen availability and actively selects against invasive plant species and prefers particular native plants. This information will be critical in hedgerow improvements because it provides detailed information of plants that are preferred.

I found no significant differences in the pollen protein content between native and invasive species present in sites and found only one native species that had significantly lower nitrogen than all the others species. However, the protein content of plant species that B.vosnesenskii collected from was significantly higher than those it did not collect across site date combinations. This suggests that bees preferentially forage on plants within the community that have higher protein content.

Impacts and Contributions/Outcomes

In August of 2009, I presented the results of my study at the Ecological Society of America. I have contacted the Xerces Society about using my findings for outreach and improvement of hedgerows. During 2010, we will be working together using my data for outreach and potential additions to hedgerow installations.

Collaborators: