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

View the project final 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

Introduction

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 agricultural production.  

The best alternative to 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 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. 

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 that need boosting are: (1) a season-long food supply, (2) water, and (3) additional nesting areas. 

The farm in this experiment grew blueberries and cucurbits (cucumbers, watermelons, 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), watermelons (July), and pumpkins (July-August). May was a period of no crop flowers. 

Habitat Enrichment Corridor 

The first resource added to the habitat enrichment corridor was a season-long food supply. The corridor was seeded with different wildflower species.  The most beneficial wildflower plants identified were (1) Indian Blanket (Gaillardia pulchella) (2) Black-eye Susan (Rudbeckia hirto), (3) Tickseed (Coreopsis lanceolata) and (4) Spotted Bee Balm (Monarda punctata). Several additional wildflower plants were also tested (e.g. asters, mints, coneflowers). 

The second resource added to the habitat enrichment corridor was 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 added to the habitat enrichment corridor was 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). However, 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 pollenating summer flowering crops.  Bee houses with nesting tubes were added to the corridors for cavity nesting bees. 

Studies show floral enhancements on the edges of orchards and farms have 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 (3) post-bloom period/summer dearth period (period of few floral resources). 

The main purpose of the proposed study was to assess the habitat enrichment corridors to boost native bees and beneficial wasps over the whole agricultural season. 

(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 best support bee populations during bloom of cucurbits (cucumbers, squash, watermelon, and pumpkins)? (Summer/Fall period, May-September) 

(3) 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. 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 (such as pollinating wasps, flies, and butterflies) could benefit from the addition of pollinator-friendly habitats.  Hairy flower wasps (Family Scoliidae) have been observed to occur in large numbers at several different farms in coastal plains areas of Georgia.  

Scoliid wasps are beneficial predators of pest scarab beetles (e.g. Japanese beetles) and provide pollination of numerous flowers. This study also investigated the effect of wildflower enrichment on increasing Scoliid wasp abundance in agricultural areas. 

The following key questions were addressed in the project: 

(1) Do habitat enrichment corridors stocked with food, water, and nesting areas increase native bee abundance and diversity?

(2) Which wildflower species are best at recruiting different target native bee groups? 

(3) 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 was conducted at Pinefield Eco Farm, located in Hephzibah, Georgia.  Two years of baseline data (2022-2023) was gathered on native bee abundance and diversity at this farm. The current study gathered two additional years (2024-2025) of data used to answer the objectives.  

Five objectives were examined during the project. 

Native Bee Objectives: 

Objective 1: Measure native bee abundance in blueberry and cucurbit plots during each of the 4 major periods of the growing season. 

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

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

Scoliid Wasp Objectives: 

Objective 4: Measure Scoliid wasp abundance in blueberry and cucurbit plots during each of the 5 major periods of the growing season. 

Objective 5: Determine which specific wildflowers in each of the major periods of the growing season best recruited and increased Scoliid wasp abundance.