Date of Award

Summer 8-7-2015

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Ecology and Environmental Sciences

Advisor

Francis A. Drummond

Second Committee Member

Alison C. Dibble

Third Committee Member

Aaron K. Hoshide

Abstract

The acreage of pollinator-dependent crops continues to expand across the globe. Simultaneously, honey bee hives – an annually rented commodity that growers rely on – are more expensive every year and in some cases, scarce. In response, pollinator-dependent growers seek alternative pollinators. One approach is installing bee pasture on farms, a strategy that enables systems-based farmers to become in-situ farm-scale habitat managers. This thesis first presents a review of the literature on bee pasture plantings and provides a brief overview of some methods for assessing their impacts on the pollinator community. There are three major gaps in current bee pasture research. First, can bee pasture actually enhance bee populations? Second, what ratio of bee pasture to crop is required to significantly increase pollination services in a crop field? Last, research that assesses that attractiveness of easily established, phenologically diverse region- and crop-specific flowers that are unlikely to become weedy in crop fields is still rare.

The second chapter of this thesis presents the results of a comprehensive two-year study of bee pasture plantings within the context of New England’s wild lowbush blueberry agroecosystem. Using a randomized complete block design I investigate the effects of nurse crops and mowing regimes on bee pasture establishment success in terms of floral density and species diversity. Three types of bee pasture (clovers, wildflowers, and naturally regenerating margins) were installed at four replicated sites in Maine. Bee pastures were compared in terms of both floral density and insect visitation. Bumble bees were collected at the four treatment sites, and the species’ group composition of their pollen loads were compared with those of bumble bees collected in three control sites.

Similar patterns of visitation to bee pasture are apparent among years. Analysis of visitation in the second year alone suggests that naturally regenerating agricultural margins supported 3-4 times fewer wild bee pollinators than other treatments (2 = 5.808, P = 0.055). These differences are significant when wild bees are parsed into social and solitary groups. Social bees utilize clover plantings at a significantly greater rate than solitary bees (2 = 7.269, P = 0.026) and solitary bees utilize wildflower plantings over clover and naturally regenerating plots (2 = 7.423, P = 0.024). On average, across all blueberry fields adjacent to sown bee pasture, bumble bee pollen loads contained 37% bee pasture pollen. Our findings suggest that in lowbush blueberry fields, even relatively small sown flowering strips can provide over 1/3 of the dietary pollen for bumble bees, clover plantings are highly utilized by bumble bees, and wildflower plantings show great potential to provision resources for solitary bees.

Download

Share