Cucumber Pollination with Bumblebees

Project Overview

FS11-255
Project Type: Farmer/Rancher
Funds awarded in 2011: $8,530.00
Projected End Date: 12/31/2012
Region: Southern
State: South Carolina
Principal Investigator:

Annual Reports

Commodities

  • Vegetables: cucurbits
  • Animals: bees

Practices

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

    Summary:

    Bumble bee and honey bee pollination of cucumbers.

    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 assesses the value of bumble bees (Bombus impatiens), in addition to honey bees, for pollination of cucumbers (Cucumis sativus) in the Lexington, SC area. We compared 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

    Introduction

    One 2-5 acre field was pollinated with three honey bee colonies per acre (approximately 20,000 – 30,000 honey bees per colony), and one 2-5 acre field was pollinated by four bumble bee colonies per hectare (one hectare = 2.4711 acres). The yields from the two fields were 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. (http://www.extento.hawaii.edu/kbase/reports/cucumber_prod.htm). The same cucumber variety were 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 assessed the use of bumble bees as compared to honey bees, and a doubling of honey bee colonies.

    Project objectives:

    This research assess the value of bumble bees (Bombus impatiens), in addition to honey bees, for pollination of cucumbers in the Lexington, SC area. We compared 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

    One 2-5 acre field was pollinated with three honey bee colonies per acre (approximately 20,000 – 30,000 honey bees per colony), and one 2-5 acre field pollinated by four bumble bee colonies per hectare (one hectare = 2.4711 acres). The yields from the two fields were 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. (http://www.extento.hawaii.edu/kbase/reports/cucumber_prod.htm). The same cucumber variety was planted within days of each other in the early May time frame, for pollination and picking the end of May to first part of June. We assessed the use of bumble bees as compared to honey bees, and a doubling of honey bee colonies.
    Objectives/Performance TargetsCucumbers: Honey bee hives and bumble bee colonies were moved into the field when there is 15-20% bloom (2). Pollination continued 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 was 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 were 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 were 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 were established in each of the fields.

    The bee visits and yields from the subplots in each field were recorded. Ten flowers were watched for 10 minutes and the number of honey bees and bumble bees visiting the blooms were counted. This was repeated with different flowers for a total of 30 minutes of counting per field. Thirty minutes of counting occured each day for one week after the honey bees and bumble bees were moved into the field. The following table was 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 were counted, weighed, and graded based on current grading standards. A comparison of the mean yields and their variances from the two fields was conducted. Based on the statistical analysis, a financial analysis looking at the yields with respect to the variable cost was 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.