Development of best use practices on commercial colonies of Bombus impatiens on crops in Delaware

Project Overview

Project Type: Partnership
Funds awarded in 2012: $5,696.00
Projected End Date: 12/31/2013
Region: Northeast
State: Delaware
Project Leader:
Dr. Deborah Delaney
University of Delaware
Jacquelyn Marchese
University of Delaware

Annual Reports


  • Fruits: melons, berries (strawberries)
  • Vegetables: cucurbits
  • Animals: bees


  • Animal Production: general animal production
  • Education and Training: on-farm/ranch research
  • Natural Resources/Environment: wildlife

    Proposal abstract:

    This study has been developed in response to the recent declines in honey bee populations. This study is looking to seek out alternative crop pollinators for growers who are concerned with over rising costs and decreasing survivability of the traditional honey bee pollination units. The native Bombus impatiens (Common Eastern Bumble Bee) will be investigated to determine the efficacy of this species as a replacement or supplementary pollinator to populations of honey bees. The results of this study will aid in the development of a ‘Best use Practices’ document for growers throughout the state of Delaware using commercial bumble bee hives in their fields. Ultimately, this document will help growers efficiently and economically meet the pollination requirements for strawberries, watermelon and pickling cucumbers. Specifically, this document will inform growers on how to utilize bumble bees to effectively pollinate their crops and if so, it will further direct on how many colonies should be purchased for the size of field, where and how colonies should be placed within the field, and other pertinent details discovered that will aid the survivability of their purchased bumble bees. If successful, this document will be economical to growers by ensuring they purchase the pollinators that will result in the greatest possible yield of their crop for each season.

    Project objectives from proposal:

    The field investigation will proceed during the spring and summer of 2011 and 2012 on six farms throughout the Kent and Sussex Counties of Delaware. There will be two main areas of investigation, each with various subsets:

    1. The Biology of Bumble Bee
    The bumble bee study includes various assays that aim at determining the most ideal conditions for a bumble bee nest. Commercial bumble bee colonies and shaded structures, currently being tested within the company, will be obtained from Koppert Biological Systems©. Quads will be situated in a variety of locations and conditions within each field. Location treatments are edge and in field placements. Colony condition treatments are full sun exposure without shade structure, full sun exposure with shade structure, wooded shade without shade structure, wooded shade with shade structure, and buried quads. The quads will be randomly assigned one the above treatments. Following the Goulson et al. (2002) study, each quad is weighed to the half gram before being opened and on a weekly basis thereafter to determine productivity of the hive. Three empty boxes provided by Koppert Biological Systems© are weighed and averaged allowing to more accurately determine biomass.

    Colonies throughout the study will be outfitted with data recorder Hobos that will be used to measure temperature and relative humidity at half hour intervals throughout the study.

    Each hive will be dissected at the end of the season or whenever it is found dead. The wax nest will be carefully stripped from the cotton structure provided from Koppert Biological Systems© and will be weighed. Perished specimens that remain in the hive in addition to wax samples will be collected and sent for pesticide analysis. This testing will determine levels of chemical accumulation found in the bees and the wax in the hive. Growers have agreed to share season long pesticide records and they will be compared to other results gathered from the analyses. Pollen within the hive will also be collected to determine foraging range and preferences previously conducted by Munidasa and Toquenaga 2010.

    Throughout the project, each pollination unit will be given a location treatment, as described above. Each treatment will look at how the unit behaves given its particular location treatment. Weight and foraging tests are two methods of determining productivity of a unit and will translate to its pollination ability on a crop during the growing season. Ultimately, the data collected from these experiments will help to determine how to best place bumble bee units within a field.

    2. The Crop Product

    Experiment broken down by crop

    Colonies will be placed in the closed strawberry high tunnels to accommodate an early harvest of the crop. Quads will then be placed outside of the high tunnels for the later crop in the field. Pollen will be collected from workers of colonies in both treatments and pollen content will be compared. Further, worker foraging will be observed to measure productivity. Each hive will be examined for 2-5 minutes each week and the activity of bees entering and leaving the hive will be recorded. Hobo data recorders will be used to determine hive thermoregulation by measuring temperature and relative humidity. The early nature of the strawberry season will allow for the greatest observation of these pollinators throughout the season and pollen basket dissection will determine what crops the bees are visiting.


    Hive weight, measured to the half gram, will be collected on a weekly basis throughout the season. Further, foraging data will also be taken here by counting bees flying in and out of the hive for 5 minutes. Watermelon surveys will also be conducted throughout the season on various farms across the area regardless of what pollinator has been placed on the field. These surveys will determine health and vigor of the plant and to determine placement and amount of flowers and fruit developed. Relative humidity and temperature will also be measured in hobo data loggers placed in colonies throughout the field. The goal of the watermelon study will be to determine how the location treatment of the quad affects longevity and production of the bumble bees, and how the presence of bumble bees on a field affects the vigor and health of the watermelon they pollinate.

    Pickling Cucumber

    Experiments in the pickling cucumber crop will mirror those in watermelon, but will also add additional foraging tests. Foraging activity data will be gathered by counting the number of flower visits per minute/bumble bee. Pollinators will then be collected along five, 50 meter transects for 30 minute intervals to determine what species were actively on the plants. Further, at each 5 meter interval along those transects, bees will be counted as they fly into the area over a one minute period. Finally, bees will be moved to a second field after the first harvest to determine the hardiness of bees after being transferred. Crop yield data is planned to be gathered by harvesting eight, 10 yard plots on various areas of the field. GPS data points of each will be taken to mark distance from bee quad. Finally, experiments will be run that will focus on the bumble bees’ ability to transfer pollen from flower to flower. For these experiments pollinators will be caged and isolated with cucumber blooms and pollen and female receptacles will be weighed to record pollen deposition. Pollen transfer frequency data will also be compiled.

    Data collected will be analyzed using one way ANOVA.

    Results from this work will be accessible to growers via conferences including the Fruit and Vegetable Growers Association of Delaware Annual meeting and Delaware Department of Agriculture Pollination meeting at Delaware Agriculture Week, the Mar-Del Watermelon Association Annual Meeting, extension publications through the University of Delaware and the Delaware Department of Agriculture and through other speaking engagements at various annual meetings celebrating native pollinators and agriculture in Delaware. As well, websites will be utilized as a vehicle to disseminate information to interested parties in Delaware. Findings from this work will also be available to the bumble bee producers, which will surely add integrity to their product and possibly increase sales within the state of Delaware. In addition to grower outreach, information from this study will be presented at professional and industry meetings including the Mid-Atlantic Vegetable Workers Conference, the Entomological Society of America, American Society for Horticultural Science, and the Pickle Packers International. With these methods we will reach over 700 growers, pollination managers, industry representatives, and agricultural professionals. The success of this project will be measured by attendance at these sessions, best management practices publications given out, and web site visits.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.