Native Bee Assessment in North Georgia Apple Orchards: Measuring Diversity and Devising Methods to Boost Abundance

Project Overview

Project Type: On-Farm Research
Funds awarded in 2012: $15,000.00
Projected End Date: 12/31/2013
Grant Recipient: Georgia Gwinnett College
Region: Southern
State: Georgia
Principal Investigator:
Dr. Mark Schlueter
Georgia Gwinnet College

Annual Reports


  • Fruits: apples, general tree fruits
  • Animals: bees


  • Animal Production: housing
  • Crop Production: food product quality/safety
  • Education and Training: display, on-farm/ranch research, participatory research, youth education
  • Farm Business Management: budgets/cost and returns
  • Natural Resources/Environment: biodiversity, habitat enhancement, wildlife
  • Production Systems: agroecosystems

    Proposal abstract:

    European Honeybees (Apis mellifera) play a vital role in pollinating the majority of all human agriculture, excluding cereals. Becoming so dependent upon a single species to pollinate such a large facet of food production has proven unsustainable, especially as worldwide declines intensify. Since 2006 alone, a 30% reduction in managed colonies of honeybees in North America has placed much of Georgia’s agriculture at potential risk by lowering crop yields and by increasing pollination costs (renting honeybee hives). Failure to act now could lead to future issues without the capital or time required to uncover adequate solutions. It is prudent to find possible solutions and alternatives before a serious crisis develops. To safeguard Georgia agriculture, researchers must not only look for answers to Colony Collapse Disorder (CCD), but they must also devise alternatives to the honeybees if researchers fail to fix CCD and the other issues decimating honeybee populations. One possible alternative to using honeybees is to use native bees for pollination services. Native bees could be used to supplement or replace the honeybee in the pollination of a specific crop. To investigate the potential native bees have for supporting commercial agriculture, a three-step approach must be taken. Step one is to perform native bee species surveys in order to know which species are present in a given farm or orchard. Step two is to identify specific native bees as potential target pollinators for certain cultivated plants. Step three is to perform minor habitat modifications to increase the abundance of the target native bees. The two most important modifications would be (1) adding native bee nesting habitat useful to the target native bee and (2) adding floral resources (e.g. wildflowers, which will provide food resources for the bees when the target crops are not flowering). Once researchers have identified these target native bees, U.S. agriculture will be afforded not only a new insect pollinator, but a sustainable and natural one as well. The current project examines the use of native bees in commercial apple production in Georgia. Studies from previous years have identified the target native bees (Andrena species) best suited for the pollination of apples. This year, an additional survey will confirm the target native pollinators, as well as measure the pollination success of these bees. In additional, preliminary habitat enrichments will be investigated. The overall result of this research will be to reduce Georgia farmers’ reliance on commercial honeybees.

    Project objectives from proposal:

    The project has three main objectives.

    Objective 1 – Survey of Native Bees in Georgia Apple Orchards
    A survey of native bees will be conducted in four North Georgia Apple Orchards. This will be the third year of the survey. Long-term studies have the ability to assess the effects of weather (e.g. rainfall, global warming), and bloom period (e.g. early vs. late) on native bee populations as well as measure shifts in native bee populations.

    Objective 2 – Measuring the Success of Native Bees in Apple Pollination
    Ten apple trees will be selected at random. Several branches of each tree will be enclosed by mesh netting of a gauge small enough to exclude the honeybee.

    In each enclosure, a pan trap will be placed inside to collect a sample of native bees that enter the enclosure to pollinate the apple flowers. The enclosure will be placed over the trees several weeks prior to the apple bloom and removed several weeks after the apple flowers fall off the apple trees.

    The pollination success will be evaluated by three measurements: (1) the number of apples produced per branch; and (2) average size of apples produced, and (3) seed count.

    Native bees captured in the pan trap will be identified to species. This will assist in identifying the ideal target pollinators of apples.

    Objective 3 – Determine the Potential Usefulness of Nest Boxes in Boosting Native Pollinator Abundance

    Small orchards surrounded by areas of natural vegetation (e.g. Mountain View Orchard) have a much larger abundance of native bees than larger orchards (e.g. Mercier Orchards) (Schlueter and Stewart, unpublished data).

    The Mountain View Orchard is a typical small-scale orchard surrounded largely by natural vegetation (continuous tracts of habitat impacted little by humans). Mercier Orchards, alternatively, is a large-scale orchard surrounded by limited natural vegetation fragmented by human activity through agricultural and residential operations. Due to its massive orchard size (the largest orchard in GA, with over 215,000 apple trees), we have found that this orchard has a reduced diversity and number of native bees, particularly as a person moves to the center of the orchard. Can nest boxes help boost native pollinator abundance?

    We will place nest boxes in the Mountain View Orchard. In September, we will retrieve the nest boxes from the orchard. We will measure the native bee species diversity and abundance in the nest boxes. The nest boxes from the Mountain View Orchard will be placed in the center of the Mercier Orchard to overwinter for use in the next growing season.

    Looking ahead; in the following growing season of 2013, we will determine if the additional nest boxes increased the number and diversity of Andrenid bees. Additional projects in 2013 will determine if increased abundance can be maintain by placing additional nest boxes (habitat sites) around the orchard.

    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.