Cucumber Pollination with Bumblebees

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2011: $8,530.00
Projected End Date: 12/31/2012
Region: Southern
State: South Carolina
Principal Investigator:
David MacFawn
Rawl Farms

Annual Reports


  • Vegetables: cucurbits
  • Animals: bees


  • Education and Training: extension, farmer to farmer
  • Farm Business Management: feasibility study
  • Production Systems: holistic management

    Proposal summary:

    Wild pollinator numbers have diminished over the last 30 or so years in the Lexington, SC area and worldwide. Farmers previously relied on wild pollinators to provide a substantial amount of pollination for their crops. Honey bees have in recent years been used to pollinate crops such as squash, cucumbers, and melons due to the large number of bees per hive. Honey bee colonies may have 30,000 honey bees whereas a bumble bee nest may have only 300 bumble bees. However, honey bees do not fly in inclement weather that includes lower temperatures and wind (1). Honey bees also tend to go down rows whereas bumble bees tend to go across rows or are more erratic in their foraging (1). Farmers are becoming more interested in having alternative pollinators to ensure proper pollination for their crops. This research will assess the value of bumble bees (Bombus impatiens), in addition to honey bees, for pollination of cucumbers in the Lexington, SC area. We will be comparing fields pollinated with introduced honey bee colonies to fields with introduced bumble bee colonies. We know that in both cases there will be pollination from extraneous pollinators that we did not introduce, but we assume that it will be either negligible or equal and our differences will come from differential pollination efficiencies of our introduced pollinators. (1) Mader, Spivak, Evans, “ Managing Alternative Pollinators, A Handbook for Beekeepers, Growers, and Conservationists,” SARE / NARES, February, 2010 ISBN 978-1-933395-20-3 It is proposed that one 2-5 acre field be pollinated with three honey bee colonies per acre (approximately 20,000 – 30,000 honey bees per colony), and one 2-5 acre field be pollinated by four bumble bee colonies per hectare (one hectare = 2.4711 acres). The yields from the two fields will be assessed to determine the difference between honey bee pollination and bumble bee pollination. Previously, 1.5 honey bee colonies were utilized rather than three honey bee colonies. Recent reports indicate the production value of 3 honey bee colonies per acre rather than one. ( The same cucumber variety will be planted within days of each other in the early May time frame, in anticipation of pollination and picking the end of May to first part of June. We will be assessing the use of bumble bees as compared to honey bees, and a doubling of honey bee colonies.

    Project objectives from proposal:

    Cucumbers: Honey bee hives and bumble bee colonies will be moved into the field when there is 15-20% bloom (2). Pollination will continue for about a week prior to harvesting. Flowers pollinated less than two hours prior to overhead irrigation fail to produce fruit if water enters the corolla. In addition, it will be determined the length of time that a bumble bee nest is strong enough to provide adequate pollination services, i.e. how many crops. Bombus impatiens recommendations indicate they should last approximately 8 weeks.

    In 2- 5 acre fields (this is the minimum size field that is economically viable due to the size of the farmer’s equipment):

    Honey bee colonies containing 20,000-30,000 bees will be placed in groups of four colonies around the edges of the field in quantities of 3 colonies per acre rather than the historic 1.5 colonies per acre.

    Bumble bees will be placed in cool, shaded locations around field #2 at a density of 4 bumble bee colonies per 2.5 acres. The two fields will be located approximately 2-3 miles apart. Three subplots of similar size will be established in each of the fields.

    The bee visits and yields from the subplots in each field will be recorded. One person will be hired to count the honey bee visits and bumble bee visits for each field, for a total of two people for two fields over the crop blooming period. Ten flowers will be watched for 10 minutes and the number of honey bees and bumble bees visiting the blooms will be counted. This will be repeated with different flowers for a total of 30 minutes of counting per field. Thirty minutes of counting will occur each day for one week after the honey bees and bumble bees are moved into the field. The following table will be consulted (2) to determine adequate bloom bee visits for cucumbers ( this table was generated in Michigan and may be different for the Lexington, SC area, i.e. bees typically do not visit booms in the middle of the day due to the heat but they still need approximately 10-15 bee visits per bloom per day) :

    Time of count Min # bees/30 flowers/30 minutes
    8:00-9:00 1
    9:00-10:00 3
    10:00-11:00 9
    11:00-12:00 13
    12:00-1:00 16
    1:00-2:00 13
    2:00-3:00 11
    3:00-4:00 7
    4:00-5:00 5

    The cucumbers from each plot will be counted, weighed, and graded based on current grading standards. A comparison of the mean yields and their variances from the two fields will be conducted. Based on the statistical analysis, a financial analysis looking at the yields with respect to the variable cost will be conducted to determine the payback for just honey bees, and just bumble bees.

    (2) Joe M. Graham, “ The Hive and the Honey Bee,’ 1992, ISBN 0-915698-09-9, pp 1060-1062

    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.