Boosting Native Pollinator and Beneficial Insect Abundance from Spring to Fall Across Multiple Crops Using Water, Nesting, and Wildflower Enrichments.

View the project report

Commodities

• Fruits: berries (blueberries)

Practices

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

The U.S. food supply is endangered by declines in honeybees and a lack of possible pollinators in the future.  Compounding the problem is a loss of native pollinator habitat, global climate change, pollution, and the need to boost production. 

The best alternative to honeybees is the native bees already present in the environment [9-15,20].  With nearly 3500 species in North America alone, the diversity of different forms, pollen-strategies, and behaviors of native bees provides a wide range of use for agricultural operations. Relying on several native bee species with varying behaviors and adaptations is a solution to varying climate conditions resulting from global climate change [19].

Past research suggests two main methods of boosting native bees in agricultural areas: (a) providing nesting habitats and (b) providing additional floral resources (particularly during periods of low food availability).

Based on current studies of Eastern Central Georgia (e.g. coastal plain areas with sandy well-drained soils), 3 main habitat enrichments are: (1) season-long food supply, (2) water, and (3) additional nesting areas need boosting.

The farm in this experiment grows blueberries and cucurbits (cucumbers, watermelon, and pumpkins), allowing native bee activity to be measured over the whole growing season.  These crops provide a range of flowering times: blueberries (March-April), cucumbers (June-July), watermelon (July), and pumpkin (July-August). May will be a period of no crop flowers.

Habitat Enrichment Corridor

The first resource to be added to the habitat enrichment corridor is a season-long food supply. Stocking the corridor with different wildflower species will provide a season-long food supply.  The most beneficial wildflower plants have been identified as (1) Indian Blanket (Gaillardia pulchella) (2) Black-eye Susan (Rudbeckia hirto), and (3) Swamp Sunflower (Helianthus angustifolius). Several additional wildflower plants will also be tested (e.g. tickseed, asters, mints).

The second resource to be added is water.  Current climate patterns in Central Georgia impacted by global climate change indicate very hot summers with few days of rainfall.  The lack of water may keep native bees from certain agricultural areas. It should be noted that managed bees, like honeybees, are provided with additional food and water resources at their hives by their beekeepers.

The third resource to be added is nesting habitat. In the Southeastern U.S. region, the most useful native bees are ground nesting bees that could also nest in the wildflower corridors. These ground nesting native bees include Southeastern Blueberry Bees (Habropoda laboriosa), sweat bees (Genera: Augochlorella, Halictus, Lasioglossum), and bumble bees (Genus Bombus). Cavity nesting bees such as Mason Bees (Genus Osmia) may play a role in early season pollination, while leaf cutter bees (Genus Megachile) may also play an important role in summer flowering crops.  Bee houses with nesting tubes will be added to the corridors for cavity nesting bees.

Studies have shown floral enhancements on the edges of orchards and farms have had a significant effect in recruiting or bringing in more native bees. Now, scientists need to explore what is really going on in the wildflower patches during each major period of the growing season.  Specifically, we need to know what is going on during the (1) pre-bloom period, (2) bloom period of the target crop, and the (3) post-bloom period/summer dearth period (period of few floral resources).

The main purpose of the proposed study is to assess the habitat enrichment corridors to boost native bee and beneficial wasps over the whole agricultural season.  The results of the proposed project will answer:

(1) Which wildflower species are the best at recruiting native bees pre-bloom and during bloom of the blueberries?  (Spring Period, March -April)

(2) Which wildflower species are the best at maintaining native bees during post-bloom period (a time of no flowers)? (a time of no flowers)?  (Early Summer, May)

(3) Which wildflower species best support bee populations during bloom of cucurbits (cucumbers, squash, watermelon, and pumpkins)? (Summer/Fall Period, June-September)

(4) Which wildflower species are the best at maintaining native bees during post- bloom (a time of no flowers) of cucurbits? (October)

These answers will assist in the development of an ideal wildflower mix that will boost target native bee abundances by providing the correct wildflower resources.  These resources will both increase native bee pollination activities within the farm during the current season and will promote greater offspring production, leading to higher abundances of native bees in subsequent seasons.

Each region of the U.S. varies in farming conditions, bloom times, and variety of native bee species available for pollination activities [20,21].  Regional studies such as the proposed study are essential in gathering accurate information on which wildflower species have the best native bee recruitment characteristics.

Past research of Georgia’s native bees has focused on the northern apple producing areas of Georgia.  This will be one of the first studies of native bees in Eastern Central Georgia (e.g. coastal plain area with sandy well-drained soils).  Thus, the study’s results will also allow a comparison of native bees’ seasonal diversities and abundances between native bees in Northern Georgia (clay soils) versus Eastern Central Georgia (sandy soils).

Other pollinators including pollinating flies, pollinating wasps, and butterflies could benefit from the addition of pollinator friendly habitats.  Current pollinator studies have identified native beneficial wasp species present in central and southern Georgia farms (personal observation). Specifically, hairy flower wasps (Family Scoliidae) have been observed to occur in large numbers at several different farms. 

This group of wasps has been identified as beneficial predators of pest beetles and provide significant pollination of numerous flowers [21]. Thus, this study will also study and survey wasps in addition to the native bees.  It should be noted: Scoliidae wasps are not often seen in the North Georgia (clay soils) orchards and farms.

The proposed study plans to examine the following key questions:

• Do habitat enrichment corridors stocked with food, water, and nesting areas increase native bee abundance and diversity?
• Which wildflower species are best at recruiting different target native bee groups?
• Do habitat enrichment corridors stocked with food, water, and nesting areas increase other beneficial insects (e.g. hairy flower wasps)?

To measure the effectiveness of habitat enrichment corridors, we will monitor native bees and beneficial insect abundance and diversity from March to October. This study will be conducted at Pinefield Eco Farm, located in Hephzibah, Georgia.  We have gathered 2 years of baseline data on native bee abundance and diversity at this farm.

On the farm, we will create six plots of blueberry bushes (3 control and 3 experimental) and six plots of cucurbits (3 control and 3 experimental). Each experimental plot will have an adjacent habitat enrichment corridor. 

Blueberry Plot (Blueberries flower March – April)

The three blueberry “experimental” plots will consist of 5 rows of blueberry bushes roughly 1500 ft² (50 x 30 feet) with an adjacent habitat enrichment corridor roughly 400 ft² (50 ft x 8 ft). The three blueberry “control” plots will have the same layout, but will lack the habitat enrichment corridor.  The blueberry experiment and control plots are separated by a small forest (more than 1000 feet across).

Cucurbit Plots (cucumbers, squash, watermelon, pumpkins) ( Cucurbits flower June-August)

The three cucurbit “experimental” plots will consist of 12 rows: 3 cucumber, 3 squash, 3 watermelon, and 3 pumpkin (roughly 1200 ft² (50 x 24 feet) with an adjacent habitat enrichment corridor roughly 200 ft² (50 ft x 8 ft). The three cucurbit “control” plots will have the same layout but will lack the habitat enrichment corridor.  The blueberry experiment plots and an additional open area will separate the cucurbit control and experiments plots. 

The Habitat Enrichment Corridor (Water, nesting, and food enrichments)

The habitat enrichment corridor will be seeded with 20+ wildflower species.  The main wildflower species of interest are: (1) Indian Blanket (Gaillardia pulchella) (2) Black-eye Susan (Rudbeckia hirto), (3) Swamp Sunflower (Helianthus angustifolius).  The goal is to have 3 or more wildflower species blooming in each of the seasons (spring, summer, and fall).

In the center of each habitat enrichment corridor, a bee house with 6 – 9 mm diameter natural reed clusters (300 reeds per corridor) will be placed.  Spring bees (e.g. Mason Bees) and Summer Bees (e.g. Leaf Cutter bees) will use this nesting resource.  Nest boxes will be 4 feet above the ground on poles. In October, we will assess which diameter size reed worked best. 

In the center of the habitat, a bee watering station will be placed next to the nest boxes. We will evaluate 3 types of watering stations (Foxhound 1/2 gallon reservoir, Sunvara 8 oz bee water feeder, and Zavhoz feeding bowl feeder). The 3 types of watering stations will be zip tied to 2 stacked cinderblocks for stability. 

Objective 1: Measure native bee and beneficial insect abundance in blueberry and cucurbit plots during each of the 5 major periods of the growing season.

To gather the data needed to test this objective, we will use a range of sampling methods proven to accurately sample native bee abundance and diversity in North Georgia Apple Orchards, based on a modified Bee Inventory Plot Design [11]. 

This project begins in April 2024.  However, we will perform 12 samples each year (March (x2), April (x2), May (x2), June (x2), July (x1), August (x1), September (x1), and October (x1) in each plot. Pre-Bloom Sampling (March), Blueberry Bloom (April), and Post-Bloom/Summer Floral Dearth (May) and Summer Cucurbit Bloom (June, July, August) and Post-Bloom (September, October).  

Each of the six plots will be passively sampled using a total of 6 sets of bowl traps (each set consists of 1 UV blue bowl, 1 UV yellow bowl, and 1 white bowl), 2 vane traps, and 1 malaise trap. In addition, active sampling will be performed by timed sweep netting of 30 minutes in each plot.   

In each plot, the bowls will be laid out in an “X” formation from the plot’s site corners. One vane trap will be placed on one side of the plot and the other vane trap will be placed on the opposite side of the plot. The malaise trap will be place on the edge of the plot in the middle row. 

All bee samples collected will be stored in 95% ethanol and taken back to Georgia Gwinnett College.  Professor Schlueter will lead 10-12 GGC undergraduates in sorting the samples and identifying the bees. (Most students are from underrepresented groups - See Diversity, Equity and Inclusion grant section below)

Objective 2: Assess the success of each type of enrichment in the habitat enrichment corridor.

Wildflower Assessment

We will assess the success of wildflowers by doing a bee visitation count.  Each collection day students will perform a 30-minute timed bee count on the wildflowers.  Students will observe and record which species of wildflower had a bee visiting it.  If possible, students will take a photograph of the bee for later identification.

Nesting Assessment

Bee houses with 6 – 9 mm diameter natural reed clusters (300 reeds per enrichment corridor) will be placed in each plot.  In October, we will assess which diameter size reed worked best by measuring the reed diameter size of each reed and determining if stem nesting bees used the reed for nesting.

Water Assessment

We will evaluate 3 types of watering stations (Foxhound 1/2-gallon reservoir, Sunvara 8 oz bee water feeder, and Zavhoz feeding bowl feeder).  Students will observe and record which water station had a bee visiting it.  If possible, students will take a photograph of the bee for later identification.

Objective 3: Determine which target bee species is present on specific wildflowers in each of the major periods of the growing season.

There are five major periods of concern: Pre-bloom, Bloom, and Post-Bloom/Summer Dearth (Poor food availability in farms), Summer Cucurbit Bloom (June, July, August) and Post-Bloom (September, October).

Researchers use video cameras to monitor flowering wildflower species. Video cameras will record each bee that lands on a targeted wildflower species.  After performing the bee visitation count (objective 2), students and researchers will walk through the habitat enrichment corridor, attempting to photograph and/or collect bees.  Collected bees will be taken to GGC for identification.