Improving Pollination through bumblebee habitation; Evaluation of nest box types in bumblebee colonization

Final Report for ONE08-079

Project Type: Partnership
Funds awarded in 2008: $9,833.00
Projected End Date: 12/31/2009
Region: Northeast
State: Pennsylvania
Project Leader:
Steve Bogash
Penn State Cooperative Extension
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Project Information

Summary:

Note to the reader: Diagrams and other resources referenced in this report are available on request from Northeast SARE. Call 802-656-0471 or send e-mail to nesare@uvm.edu and request final report materials for ONE08-079.

One of the most challenging issues for present day commercial agriculture is the recent dramatic loss of honeybee colonies, which are currently used as the main source of pollination for horticultural crops in the United States. A solution to this problem is encouraging farmers to shift their reliance from honeybees to native pollinators. One of the most efficient species of wild bee, the bumblebee (Bombus spp.), has many advantages.

This project is based upon the premise found commonly in research relating to bumblebees that only a small number of overwintering, fertilized queens, create successful nests. Although the numbers vary somewhat, it is estimated that only 1% of emerging queens develop new colonies. Mice and ant depradation as well as loss of habitat are considered to be the primary culprits impacting colony success.

In this project, we will examine various bumblebee nest box designs along with other variables relating to nest success in order to develop recommendations and plans for growers. This work should result in specific practices that growers can adopt in order to increase their native bumblebee pollinators, thus improving their overall fruit quality.

Introduction:

One of the most challenging issues for present day commercial agriculture is the recent dramatic loss of honeybee colonies, which are currently used as the main source of pollination for agricultural and horticultural crops in the United States. The problem is compounded by the fact that it is a risky endeavor to overly rely upon on a single species of bee, Apis mellifera (honeybee), to pollinate and insure the continuation of much of the nation’s food. The honeybee's crucial role for American farms is illustrated by a Cornell University study showing that honeybees pollinate more than $14 billion worth of seeds and crops in United States. Furthermore, approximately one third of the food consumed in the U.S. is produced through honeybee pollination, according to the Vice President of the American Beekeeping Federation, Zac Browning.

A solution to this problem is encouraging farmers to shift their reliance from the non-native honeybees to the native pollinators. One of the most efficient species of wild bee, which can pollinate a variety of commercially important crops including vegetables, fruit, berries, fodder and medicinal plants, is the bumblebee (Bombus spp.), which presents the following advantages:

-They are active earlier in the spring than honeybees.

-They grab the anthers of flowers and shake them (an important action for freeing the pollen in some blossoms).

-They work on cool overcast days, when honeybees remain in their hives.

-They tend to stay in one crop rather than flying between crops, thus insuring higher success in pollination.

-They stimulate the honeybee to work more efficiently when are in competition, etc.

We propose that a fresh evaluation of how to build and install nesting boxes for bumblebees is necessary to prevent further decline in the number of bumblebee colonies, which are dwindling due to a lack of suitable nesting sites and the very low survival rate of the queen over winter. Additionally, the bumblebee's rising potential in commercial value makes new information on how to provide nesting boxes that will nurture colonies on farms essential for creating a symbiotic relationship between farmer and bumblebee.

Even though many studies have been conducted on bumblebees, information on how to establish and maintain colonies for the agricultural industry is incomplete, inconsistent or contradictory. We are prepared to investigate the benefits of bumblebee colonies over the floundering system of honeybee colonies for commercial purposes as we believe that meaningful knowledge in the field will be of vital importance in developing and maintaining local agricultural business.

For greenhouses crops, several commercial bumblebee breeding companies presently rear bumblebee colonies to sell to plant growers. Considering that the hives for sale have a life span ranging from four weeks to three months, at a price of $700-$1000 for the multiple colonies necessary to pollinate a acre of crop, we believe that a more capable and inexpensive way of introducing long-term bumblebee colonies for the pollination of outdoor crops would be welcomed.

Some of the publicized research concerning methods of establishing bumblebee colonies, such as through the construction of nest boxes, includes the following: Frison, T.H. 1926, Fye, R.E. and J.T. Medler. 1954, Hobbs, G.A., Virostek, J.F., and W.O. Nummi. 1960, Prys-Jones & Corbert 1991, Munn 1998, Kearns & Thomson 2001.

Two main options for bumblebee nest box construction were gleaned from the research: one opinion is that the ideal nest box should have two chambers (one as a nest and the other as a vestibule where food can be provided and the bees can defecate), while the other opinion is that a one chamber box being perfectly sufficient.
Preceding research also tell us that bumblebees utilize their sense of smell and sight to hone in on ideal nesting places. Because of this, some researchers suggest that positioning the man-made nests near obvious land marks such as trees, posts, stumps, rocks, etc. will yield better results. Other studies have shown that drawing some type of pattern at the entrance helps the bees to locate their nest faster. For our project, we have taken into account the bumblebee’s perception of color as indicated by the research. Earlier studies have found that bumblebees can detect colors in the blue range (blue, indigo, violet and purple), and yellow range (yellow, red-yellow, green-yellow, yellow-green), and are most sensitive to hue-discrimination in the violet range and the blue-green to green spectral range, and cannot distinction between black and red.

One of the unresolved issues in the literature is if the nesting height is of any significance to the bumblebee, and if so, what is the optimal height for above ground domiciles. The earlier research presents three main possibilities: 1) the best height for nest boxes is at least 15 inches above the ground, 2) height should be four feet above the ground, and 3) the height of the nest is not important as long the nest is protected from flooding, excessive humidity, wind and heat.

As there is no general consensus in previous research in standards for bumblebee nest boxes, and there is scant information on the success rate of different types of nests, we will test several models based on variations in design, color, and height to determine the most suitable conditions for a robust bumblebee colony. We also recognize that the previous research on bumblebees is not readily available to farmers and therefore, as extension educators, it is our duty to share with our cooperating farmers proven, practical, and user-friendly guidelines in how to install man-made nest boxes with the express purpose of creating and maintaining a system of crop pollination with the bumblebee population.

Our goal is to determine what the most desirable habitat conditions are to encourage bumblebees with man-made domiciles. From this work we will develop a set of recommendations with construction plans and practices that growers can use to increase their on-farm success with bumblebees.

We will experiment with two types of wooden bumblebee nest boxes: one type will have just one chamber (for more details we have provided diagram B1), while the other will be comprised of two chambers (one as a vestibule and the other as a nest; diagram B2). Both types of the two nest boxes will be distinguished in the following ways: 20 will be painted yellow, 20 painted purple, and 20 left natural. The total of the 120 nest boxes will be installed at the following two heights: 16 inches above the ground and four feet above the ground. We have attached diagram D1 to the back of the application to help illustrate the nesting box categories.

By doing that, we hope to determine what type of box, and in what setting, attracted and housed the most populous and successful bumblebee colonies. We will also identify which species of bumblebees formed the colonies by capturing an individual and submitting it to an entomologist for Identification. Knowledge of the specific species will help to identify which bombus spp. are using these nests in order to assist in further refining of any final project recommendations.

To protect the colony against stress we will make observations biweekly, which will allow sufficient time to get a good idea of the growth rate of the colony by measuring the hives or counting the individuals. We aim for low-intrusive methods of observing and gathering data on the colonies through the usage of infrared or light amplifier equipment during the night. Each nest box will be constructed with a hinged panel over a transparent panel to allow these observations.

Results from the 2008 program will be used to refine similar projects in future years. We expect that the initial 120 bumblebee domiciles on 5 farms will provide us with significant results that will be useful in not only beginning the development of specific recommendations, but in increased numbers of bumblebees pollinating cooperators crops.

Project Objectives:

Based on the research data gathered, we intend to provide the farmers with a set of recommendations including construction plans and practices that growers can use to increase their on-farm success with bumblebees. A second objective is to increase the producers' awareness of the importance and sustainability of the native bees' pollination services over those provided by honeybees.

Cooperators

Click linked name(s) to expand
  • Tim Brown
  • Jenifer Halpin
  • Chris Mayer
  • Ben Myers
  • Bill Oyler
  • Alexandru Surcica

Research

Materials and methods:

Our goal is to determine what the most desirable habitat conditions are to encourage bumblebees with man-made domiciles. From this work we will develop a set of recommendations with construction plans and practices that growers can use to increase their on-farm success with bumblebees.

We will experiment with two types of wooden bumblebee nest boxes: one type will have just one chamber (see diagram), while the other will be comprised of two chambers (again, see diagram). Both types of the two nest boxes will be distinguished in the following ways: 20 will be painted yellow, 20 painted purple, and 20 left natural. The total of the 120 nest boxes will be installed at the following two heights: 16 inches above the ground and four feet above the ground.

By doing that, we hope to determine what type of box, and in what setting, attracted and housed the most populous and successful bumblebee colonies. We will also identify which species of bumblebees formed the colonies by capturing an individual and submitting it to an entomologist for Identification. Knowledge of the specific species will help to identify which bombus spp. are using these nests in order to assist in further refining of any final project recommendations.

To protect the colony against stress we will make observations biweekly, which will allow sufficient time to get a good idea of the growth rate of the colony by measuring the hives or counting the individuals. We aim for low-intrusive methods of observing and gathering data on the colonies through the usage of infrared or light amplifier equipment during the night. Each nest box will be constructed with a hinged panel over a transparent panel to allow these observations.

Results from the 2008 program will be used to refine similar projects in future years. We expect that the initial 120 bumblebee domiciles on 5 farms will provide us with significant results that will be useful in not only beginning the development of specific recommendations, but in increased numbers of bumblebees pollinating cooperators crops.

Research results and discussion:

We built and installed over 120 wooden bumblebee domiciles on our five cooperator farms. The farms were selected based on a reasonable geographic spread that was still accessible for travel, experience working with the cooperators, crop diversity and pesticide application procedures.

Another 30 nest boxes of various styles were distributed to interested home gardeners based on newspaper articles supporting the overall project. All cooperating parties agreed to keep the area around the domiciles undisturbed and free of pesticides. Additional information was provided on the planting of pollen and nectar bearing plants that were considered bumblebee-friendly.

The domiciles on cooperator farms were visited bi-weekly starting in June 2008. While the domiciles were originally installed in April, we wanted to allow time for the colonies to get well established before any disturbance from opening the observation ports. Images along with samples of colonizing bees were collected from all colonies. All bee samples were submitted to the Penn State University Entomology Lab for identification.

Past research has indicated very low and variable colonization of man-made bumblebee domiciles. This projects success reflected those same characteristics with colonization of bumblebees at or below 1%.

As this project has developed, we have learned a great deal about the bumblebee population in the area that we have installed nests. While our original research indicated as many as 13 Bombus species in this region, in reality, the local population is dominated by Bombus impatiens. This bumblebee primarily nests in the ground in abandoned mouse nests. Our above-ground domiciles simply were not of interest to this species queens as they searched for new nest sites. The 2 domiciles that were colonized were both with Bombus griseocollis.

Another factor that likely influenced the success of this years nesting was the date of installation. Due to the delay in construction after the grant announcement, the domiciles were not installed until well into April. This probably missed many emerging queens in the relatively early spring experienced by this area.

The freshness of the finish on the boxes may have been another factor in colonization success.

Orchard Mason Bees, Osmia lignaria colonized 12.5% of domiciles. Ants, Paper wasps, Solitary wasps, spiders and field mice made use of several other domiciles.

As noted above, the predominant bumblebee species in the area served is Bombus impatiens, a ground nesting species. New models of domiciles will need to take this into account. Since this is the primary species used by greenhouse tomato growers as purchased pollinators, it is likely that the growth in the greenhouse tomato industry has had an impact on wild bumblebee species.

Research conclusions:

Discussion of this project and its' initial results at farm meetings in 2008 and 2009 has generated significant interest in further development of domiciles along with nectar and pollen habitat. Along with increased interest in pollinators in general by both the public and growers has been a groundswell of interest by growers in more sustainable practices in pest management. Frequently, growers use pollinator sensitivity to specific pesticides and the timing of applications as criteria in decision making. A group of 384 pesticide applicators at a professional pesticides applicators meeting in December 2008 indicated that 94% of those sampled considered the sensitivity of pollinators to pesticides as an important criteria in their selection of materials.

Participation Summary

Education & Outreach Activities and Participation Summary

Participation Summary:

Education/outreach description:

Talks, Workshops and Presentations:

-Franklin County Beekeepers Meeting, Franklin County Cooperative Extension Office. Presentation.

-Wilson College Field Day, Fulton Sustainable Farm. Presentation.

-Summer Garden Experience, Penn State Southeast Research and Extension Center, Manheim, PA. This was a hands-on workshop building bumblebee domiciles.

-PASA Field Day at the Dickinson College Farm. Presentation.

-Penn State Fruit Research Laboratory Open House. Presentation.

Publications:
-Migratory Beekeeping- Second Thoughts
-B-stings
-The Queens Life; Understanding Bumblebees
-Understanding Bumblebees
-Domicile construction plans

Project Outcomes

Project outcomes:

Farmer Adoption

Since we have yet to discover the key to increasing the success of bumblebee Queens in developing new colonies using our domiciles, we have yet to recommend adoption by farmers of this method of pollination supplementation. To date, only our farmer cooperators use these domiciles.

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

Since the discovery of the predominant Bombus species, Bombus impatiens, in our area, we have focused our research in 2 areas. 1) How do we increase the success of the dominant species? and 2) How do we assist the other 8-13 Bombus species in successful colonization? Is another style of domicile the key to increasing the adoption of man-made nests?

Although we carefully selected farmer-cooperators based on the diversity of crops found on their farms, were their cropping patterns and the plants on their farms enough to sustain bees that must forage from April to Late October sufficient. Coupling habitat improvement with improved domiciles seems the likely direction to move the native pollinator program.

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.