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

Final Report for FS16-290

Project Type: Farmer/Rancher
Funds awarded in 2016: $10,000.00
Projected End Date: 12/31/2017
Region: Southern
State: Georgia
Principal Investigator:
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Project Information

Abstract:

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 (100×100 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.
  1. Watanabe, M. 1994. Pollination Worries Rise as Honey Bees Decline. Science 265 (5176): 1170.
  1. 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.
  1. USDA National Agricultural Statistics Service. 1977. 1976 Honey production report. United States Department of Agriculture, Washington DC.
  1. USDA National Agricultural Statistics Service. 2006. 2005 Honey production report. United States Department of Agriculture, Washington DC.
  1. Johnson, R. 2007. Recent honeybee colony declines. CRS Report to Congress.
  1. 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.
  1. Losey, J.E., and M. Vaughan. 2006. The Economic Value of Ecological Services Provided By Insects. Bioscience 56:311-323.
  1. 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.                                                                                                                                               
  2.  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.
Project Objectives:

The main goal of the study is to measure the benefits of adding three wildflower plots (100×100 ft2) in between the middle of an apple orchard.  Specifically, we measured: (1) increases in native bees attracted to the wildflower patches and (2) changes in apple production from the 2016 season compared to the previous 5 years.

Cooperators

Click linked name(s) to expand
  • Mark Schlueter

Research

Materials and methods:

In order to measure the number of native bees attracted to the wild-flower patches, we sampled the bees each week from April to October (30 weeks).  Each flower plot had 12 pan-trap sets (1 set = 1 blue bowl, 1 yellow bowl, and 1 white bowl).  Four bowl sets were placed on the out-side edge, 4 bowl sets were placed from 25 feet from the plot center, and 4 bowl sets were placed 5 feet from the plot center.  This allowed us to measure difference in: (a) insect location in the plot (edge vs. center), (b) insect color preferences, (c) time of year insect groups were present, and (d) insect abundance and diversity.

The comprehensive sample routine allowed us to measure the success of the wildflower patches in recruiting pollinator groups over the whole growing season.  The wildflower seed mix chosen has a mix of early spring blooming plants, summer blooming plants, and fall blooming plants to provide a continuous food source for the pollinators.

During the past 5 years, we have gathered comprehensive bee data at Mountain View Orchard.  Using this old data, we were able to determine the recruitment effectiveness of the three wild flower plots.

In addition, by using the apple production records, we were able to assess any changes in apple production in 2016.  While many factors (rain, temperature, etc.) impacted apple production, we were able to compare changes at Mountain View Orchard from 2010-2015 and the 2016 (wild flower patches added) seasons.  

Research results and discussion:

Graphs-Figures 1 and 2

Bee Abundance and Diversity Results

During the 2016 field season, 3779 bees were collected at Mountain View Orchard.  1797 bees were collected in the three wildflower plots (plot 1=646, plot 2 =490, and plot 3 = 661) during the 30 collection days (March-October).  In the adjacent apple orchard, 1982 bees were collected during the 14 collection days (March-October).  The majority of bees were collected during the apple bloom in April. The most common bee groups collected were the small sweat bees (Lasioglossum species) making up 32% of the total collection, mining bees (Andrena species) – 30%, bumble bees (Bombus species) – 12%, and large sweat bees (Halictus species) – 10% (See Figure 1).

The wildflower plots were designed to increase the numbers of native bees recruited to the area prior to the apple bloom. In March 2016, the wildflowers recruited significant numbers of mining bees and bumble bees to the wildflower plots.  During pre-bloom, the weekly sample event collected in the wildflower patches collected approximately 50 bees (86% mining bees and 12% bumble bees).  These numbers were much higher than in the previous five years.

Inside the apple orchard during the apple bloom in April, the 4 daily samples conducting during the apple bloom collected an average of 190 bees per daily collection event.  The most common bee groups collected were the mining bees (Andrena species) (530 of 757 bees) – 70%, bumble bees (Bombus species) (125 of 757 bees) – 16.5%, and small sweat bees (Lasioglossum species) (56 of 757 bees) – 7%.

The large numbers of mining bees (Andrena species) were similar to previous years. Andrena crataegi made up more than 60% of the mining bee species.   However, there was a very large increase in bumble bees.  The wildflower plots appeared to have boosted bumble bee abundance during the apple bloom.  More than 90% of the bumble bees collected belong to the species, Bombus impatiens.

The wildflower plots provided season long food supplies adjacent to the apple orchard during the whole growing season (March-October), including the typically food poor summer months.  During the summer and late fall period, the wildflower plots recruited and supported large numbers of native bees, in particular, the small sweat bees (Lasioglossum species), large sweat bees (Halictus species), and the green sweat bees (Augochlorella species).  Some of the summer sample events collected more than 100 Lasioglossum pilosum and L. imitatum.  It is hypothesized the extra summer and fall food supplies provided by the wildflowers both attracted native bees to the area and encouraged nesting of these native bees in and adjacent to the apple orchard during the 2016 Fall season.  Thus, during the 2017 season, large numbers of these bees (offspring from the previous year’s bees) will be available for the pollination of the apple flowers during the apple bloom in April of 2017.

Apple Production/Harvest Results

Immediate effects of the wildflower plots were observed in the huge apple crop harvested in 2016 at Mountain View orchard.  In 2016, apple production surged to 3150 bushels, an increase from an average of 2200-2300 bushels from the previous 2 years (See Figure 2).

 

Participation Summary

Educational & Outreach Activities

Participation Summary:

Education/outreach description:

The study’s results and information about native bees was presented at scientific conferences and regional farm events/trade-shows.  The results of the study were presented at the International Congress of Entomology (I.C.E. 2016) (Entomological Society of America Annual Meeting) in Orlando in September 2016.  Four different poster presentations were presented by GGC undergraduate researchers at the ABCRMS meeting in Tampa in November 2016.  A poster “Evaluating the benefits of wild flower plots to boost native bee abundance and increases in fruit production” will be exhibited at the Southern Sustainable Agriculture Working Group (SSAWG) conference in late January 2017.

In addition, the project’s results will be posted on the Bees of Georgia Website. The website address is: http://native-bees-of-georgia.ggc.edu/.  This website was created in 2015 to provide information on Georgia’s bees for farmers, researchers, and the general public. Acknowledgements to SARE are listed on the homepage.

Project Outcomes

Project outcomes:

The project was successful in implementing a change (e.g. addition of wildflower plots) in the orchard that was successful in both (1) boosting the recruitment of native bee pollinators, and (2) increasing apple production throughout the orchard.

This new practice of adding wildflower plots adjacent to orchards or farms could boost crop production and lower production costs (farmers could rent fewer honeybee hives).  In addition, wildflower plots could be a new method to recruit native pollinators in sufficient numbers to either replace or supplement the honeybee, which is in decline due to colony collapse disorder (CCD).

Recommendations:

Potential Contributions

Why should the public care about boosting native bee populations in agriculture?

Increasing the number of native bee pollinators in commercial agriculture will result in: (1) lower production costs (e.g. fewer honey bee hives rented), (2) increased food production, and (3) lower food costs for the general public.

Food security will also be improved by recruiting native bees. One-third of the human food supply will no longer be completely dependent on the honeybee.  We will have good pollination alternatives to the honeybee.  This could be critical if honeybees continue to decline or die out.

Future Recommendations

Wildflower plots clearly boost native bee abundance and increase apple production.  We should repeat the experiment in order to determine if the results are similar each year. Moreover, additional experiments need to be performed to determine which wildflower species and wildflower combinations best recruit native bees.

In order to boost native bee recruitment in early Spring next season, several additional wildflower species will be added to the plots.  It is hypothesized that early flowering (March) wildflowers will recruit even more bee species (mining and mason bees) to the apple orchard.

Wildflower plots that boost native bee pollinators are the next logical step in sustainable agriculture.

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.