Which Wildflower is Best at the Recruitment of Native Bees into Agricultural Areas? A comparison of perennial vs. annual wildflowers

View the project final report

Commodities

• Fruits: apples

Practices

• Crop Production: pollination, pollinator habitat, pollinator health
• Education and Training: on-farm/ranch research
• Natural Resources/Environment: biodiversity

Which Wildflower is Best at the Recruitment of Native Bees into Agricultural Areas: A Comparison of Perennial Verses Annual Wildflowers?

Each year, honeybees contribute $15-20 billion in pollination services to U.S. commercial agriculture. Some crop yields decrease by more than 90% without honeybee pollination. Honeybees are in decline from Colony Collapse Disorder (CCD), which puts the global food supply at risk. Today, honeybee colonies are down by 40% compared to colonies available in the 1970’s.

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 has resulted in a rapid increase in the cost of renting honeybee hives.

One possible solution to the loss of the honeybees is the native bees already present in the environment. 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.

Methods need to be developed that will recruit native bees to farms or orchards. In the past decade, studies have begun to examine native bee pollination behaviors and even how to boost bee abundances. The two most common approaches suggested are to provide additional nesting habitat and to provide additional food resources. The use of wildflowers (food resources) on the edges of target agricultural areas has recently received a fair amount of attention. However, wildflower systems have not been optimized. Since each region of the U.S. has its own unique mix of native bees, regional studies will be needed to determine the optimal mix and types of wildflowers needed to boost bee abundances.

Experiments were designed for the 2017 growing season at Mountain View Orchard, to compare and contrast annual wildflower with perennial wildflower pollinator recruitment. The three wildflower plots (100x100 ft²) installed in March 2016 were mowed down to a few inches above the soil in December 2016. This upkeep method insured ideal conditions for perennial wildflowers to bloom. Additional wildflower seeds were added to the plots in February.

In order to measure the number of native bees attracted to the wild-flower patches, bees were sampled 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 differences in: (a) insect location in the plot (edge vs. center), (b) insect color preferences, (c) the time of year insect groups are present, and (d) insect abundance and diversity.

During the 2017 field season, both annual and perennial wildflower species were present, and 4051 bees were collected at Mountain View Orchard. 2188 bees were collected in the three wildflower plots (plot 1=618, plot 2 =741, and plot 3 = 829) during the 27 collection days (March-September). In the adjacent apple orchard, 1982 bees were collected during 10 collection days (March-September). The majority of bees were collected during the apple bloom in April. The most common bee groups collected were similar to 2016, except for a lack of bumblebees. The collection’s most abundant groups included the small sweat bees (Lasioglossum species) making up 41% of the total collection, mining bees (Andrena species) - 21%, large sweat bees (Halictus species) - 9%, green sweat bees (Augochorella species) -6%, and Carpenter bees (Xylocopa species)– 5%.

In 2016, 3 wildflower plots were added adjacent to the Mountain View Apple Orchard. The average harvest of apples prior to the addition of the wildflower plots was 2225 bushels per season (based on 2014 and 2015 data). After the addition of the wildflower plots, the average apple production at the orchard surged to 3,325 bushels of apples (based on 2016 and 2017 data). The wildflower plots and the additional pollinators they recruited appear to have had a substantial impact on apple production.

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.

Main Objectives

The main objective of the proposed study is to assess the effects of perennial wildflowers in recruiting native bees, particularly the mining bees (Genus Andrena). Mining bees are likely to be the best group of native bees to pollinate early blooming crops such as apples and blueberries.

The secondary objective of the proposed study is to assess whether wildflower plots can substantially increase crop yields. It appears so in 2016. Will it occur again in 2017?

In this proposed project, we will measure the benefits of adding three wildflower plots adjacent to Mountain View Orchard in terms of (1) native bee abundance, and (2) apple production. Native bee abundance and diversity has been measured the past seven years at this orchard, providing a detailed understanding of the typical native bee biodiversity. Using past data, we will be able to measure changes in native bee abundance and diversity, and apple production due to the three wildflower plots.