Measuring the Benefits of Wildflower Plots to Boost Fruit Yield and Pollinator Abundance in Georgia Apple Orchards

Bees are nature’s best pollinators. Effective pollination is critical for fruit and vegetable crops.  In the following project, the effectiveness of adding supplemental wildflower plots to increase native bee abundance was evaluated.  It was hypothesized that adding wildflowers plots adjacent to an apple orchard would increase the number and diversity of native bees.  The results of the project showed a large increase in the number of bumble bees recruited to the apple orchard during apple bloom.  In addition, apple production surged to 3150 bushels, a huge increase from an average of 2200-2300 bushels from the previous 2 years.

Introduction

Honeybees contribute $14.6 billion in pollination services to U.S. commercial agriculture [1]. Some crop yields decrease by more than 90% without honeybee pollination [2].  Sole reliance on a single insect species, the honeybee, for the pollination of over 1/3 of the human food supply is dangerous, especially considering honeybees are in decline from Colony Collapse Disorder (CCD), which puts the global food supply at risk [3]. Today, honeybee colonies are down by 40% compared to colonies available in the 1970’s [4,5].  In 2007, CCD resulted in sharp declines in honeybees in at least 35 states, including Georgia. In the affected areas, 50% of beekeepers reported significant colony losses [6].

The reduced availability of honeybee colonies has increased food production costs and reduced potential crop yields.  In order to ensure their crops are fully pollinated, nearly all fruit, nut, and vegetable farmers rent honeybee hives. The shortage of honeybee colonies due to CCD has resulted in a rapid increase in the cost of renting honeybee hives. For example, the cost of renting a single honey bee colony used in almond pollination in California increased from $35 in the early 1990’s to $150 per colony in 2007 [6]. The potential loss or reduction of the honeybee can have a devastating effect on agricultural production.  We need to develop strategies that are less dependent on the use of honeybees in order to ensure the long-term sustainably of insect pollinated crops.

Native bees are the best alternative to honeybees, since they are already present in the local environment [7-8].  With nearly 3500 species in North America alone, the diversity of different forms, pollen-strategies, and behaviors of native bees provide a wide range of use for agricultural operations. It is estimated that native bees already annually contribute $3 billion to U.S. agriculture [9].  In addition, some native bees exhibit much greater pollination efficiency compared to honeybees [10].

Therefore, research is needed to determine how best to increase native bee populations by enriching the habitats (e.g. nesting areas) adjacent to orchards or farms. In addition, the benefits of using native bees need to be measured.  Does increasing native bee abundance result in greater fruit and vegetable crop production?

In this proposed project, we will measure the benefits of adding three wildflower plots (100x100 ft²) in the middle of two sections of the Mountain View Orchard in terms of (1) native bee abundance, and (2) apple production.  We have measured native bee abundance and diversity over the past five years at this orchard and have a detailed understanding of the typical native bee biodiversity.  Using the past data, we will be able to measure changes in native bee abundance and diversity as a result of the three wild flower plots (we will have 3 “control” apple orchards as well).  We will also be able to measure any impact on apple production using previous years of data.

During the past five years, our studies identified the mining bee, Andrena Crataegi, and its close relatives, the Melandrena, as being the ideal native bees for North Georgia Apple production.  Other excellent apple pollinating native bees identified were the Mason Bees (Osmia species), Carpenter Bees (Xylocopa virginica), and Bumble Bees (Bombus species).

Several studies have indicated that wildflower patches provide food and habitat to insect pollinators.  However, in this experiment we will have the opportunity to measure increases in native bee abundance and changes in fruit yield.  If significant increases in native bees and other beneficial pollinators are recorded, adding flower patches to Georgia agricultural areas could increase native bee abundance, significantly lower production costs, and even boost fruit yield.

By establishing a strong network of native bees in Georgia agriculture, we can make Georgia Agriculture more secure and sustainable.  In addition, an increase in reliance on native bees means that farmers will spend less money on pollination services (e.g. renting honey bee hives), thus increasing farmer profits and potentially reducing food costs for the general public.

Literature Cited

1. Morse R.A. and N.W. Calderone. The Value of Honey Bees as Pollinators of U.S. Crops in 2000. Bee Culture 128:1-15.

2. Watanabe, M. 1994. Pollination Worries Rise as Honey Bees Decline. Science 265 (5176): 1170.

3. Klein A.M., B.E. Vaissiere, J.H. Cane, I. Steffan-Dewenter, S.A.Cunningham, and C. Kreman. 2007. Importance of Pollinators in Changing Landscapes for World Crops. Proceedings of the Royal Society B: Biological Sciences 274: 303–313.

4. USDA National Agricultural Statistics Service. 1977. 1976 Honey production report. United States Department of Agriculture, Washington DC.

5. USDA National Agricultural Statistics Service. 2006. 2005 Honey production report. United States Department of Agriculture, Washington DC.

6. Johnson, R. 2007. Recent honeybee colony declines. CRS Report to Congress.

7. Schlueter, M.A. and N.G. Stewart. 2015. Native bee (Hymenoptera: Apoidea) abundance and diversity in North Georgia apple orchards throughout the 2010 growing season (March to October). Southeastern Naturalist 14(4): 721-739.

8. Losey, J.E., and M. Vaughan. 2006. The Economic Value of Ecological Services Provided By Insects. Bioscience 56:311-323.

9. Sampson, B.J., S.J. Stringer, J.H. Cane, and J.M. Spiers. 2004. Screenhouse evaluations of a mason bee Osmia ribifloris (Hymenoptera: Megachilidae) as a pollinator for blueberries in the southeastern United States. Small Fruits Review 3:381-392.                                                                                                                                               
10.  Greenleaf S.S. and C. Kreman. 2006. Wild Bees Enhance Honey Bees’ Pollination of Hybrid Sunflower. Proceedings of the National Academy of Sciences USA 103(37): 13890-13895.