Northern highbush blueberry cultivars account for 100% of the Midwestern region and 99% of the Northeastern region in the United States commercial plantations. Commercial planted acreage in the U.S. is projected to increase 33% by the year 2013. One of the most limiting and critical factors of blueberry crop production is pollination.
Inadequate pollination of blueberry blossoms results in reduced yields, reduced berry size, and berry maturity delay. A good commercial blueberry crop requires that at least 80 percent of the blossoms set fruit. To ensure a successful blueberry crop, supplemental pollination is often required which typically is done with honeybees (Apis mellifera L.). With the decline of native pollinators and honeybee populations, other pollinators need to be evaluated for blueberry crop production. Hornfaced bees (Osmia cornifrons Radoszkowski) may provide a successful sustainable alternative for pollination of commercial blueberry plants.
Our preliminary work currently funded by NESARE has shown that hornfaced bees have the ability to be a successful sustainable pollinator of blueberry. Currently there are no reports or recommendations on hornfaced bee use available for blueberry farmers. There were three objectives of this follow-up research which are; 1. to determine hornfaced bee population density requirements, 2. to determine if hornfaced bees have cultivar preferences and 3. to evaluate use of hornfaced bees by small and medium sized commercial blueberry growers in the Northeast.
This research was devastated by three major factors; death of a key individual with the project, mite contamination and the 2007 April freeze. This research provided key information that mite infestation is a bigger issue than what is currently presented in the research
There are three objectives of this follow-up research which are; 1. to determine hornfaced bee population density requirements for blueberry crop pollination, 2. to determine if hornfaced bees have cultivar preferences and 3. to evaluate use of hornfaced bees by small and medium sized commercial blueberry growers in the Northeast. Information gained from this research would fill the information gap that is present allowing growers to utilize a sustainable pollinator to increase yields with minimal input.
There were four milestones identified with this project. Milestone 1: a comprehensive list of 100 commercial blueberry growers in the Northeast that are classified as small to mid-sized U-pick operations will be generated using state extension agencies. A survey will be developed in conjunction with the WVU Extension Service and sent out to 100 targeted highbush blueberry growers identified as interested participants of using hornfaced bees as a sustainable pollinator with initial information of the benefits of use. From the original 100 growers, 25 will be selected for a two year evaluation trial.
Milestone 2: the selected 25 growers will be given hornedfaced bees, housing materials and a ‘Use and Sustainable Management of Hornfaced Bees for Blueberry Crop Production’ bulletin (developed in conjunction with the WVU Extension Service) to instruct how to properly establish, use and evaluate hornfaced bees. The growers will evaluate the bees for two consecutive growing seasons. During this same period, field and greenhouse studies will be conducted to determine bee population density requirements and cultivar preference. Milestone 3: after the second year of grower evaluation, berry yield and bee propagation data will be collected, compiled and analyzed. The 25 growers will be given a final survey to evaluate their perception of hornfaced bee use.
Milestone 4. Of the 100 originally survey growers, 15 growers will adopt the use of hornfaced bees as a sustainable pollinator for blueberry production reducing costs for supplemental pollination to ensure a good crop yield and increasing production yields allowing for a higher net return per unit of area.
Of the 100 small to medium-sized commercial blueberry growers in the Northeast targeted in this project, 15 growers will adopt the use of hornfaced bees as an alternative pollinator to increase yields and farm sustainability.
During the initial outreach phase of this project, a comprehensive list was developed of 100 commercial blueberry growers in the Northeast that are classified as small to mid-sized U-pick operations. Each of the 100 growers will be contacted and the project goals and objectives were to be presented to them. Of the 100 growers, the 25 growers that agree to evaluate hornfaced bees were to receive instructions and all of the required materials to evaluate hornfaced bee use and management for a two year period. All participants will be contacted by phone and mail at least twice during each year of the project to track progress of evaluation and to follow up on any questions or to give suggestions. As the project nears completion, the 25 growers were to be surveyed about their perception and evaluation of hornfaced bee use as a pollinator of blueberry. Data on berry yield and hornfaced bee propagation will be collected, compiled and analyzed using analysis of variance. This two year data from the 25 growers will then be used to update and provide specific recommendations for hornfaced bee use for pollination of blueberry and made available to all highbush blueberry growers. This updated bulletin will be mailed to all of the 100 growers involved in the initial outreach phase of this project. A final survey will also be mailed to the 25 participating growers to determine if barriers were encountered during this project that may have prevented them from adopting use of hornfaced bees and whether they will continue use of the hornfaced bee.
Hornfaced Bee Population Density Requirements
Currently there is no information available for recommendations on hornfaced bee population density requirements for obtaining the needed 80% bloom set to ensure a good blueberry crop. A field study will be used to determine hornfaced bee density utilizing pollinator cages and will be done at an established 7 acre blueberry farm, McConnell Berry Farm, owned and operated by Robert and Debby McConnell located in Independence, WV. The selected cultivars that will be used will consist of ‘Jersey’ and ‘Bluecrop’ (Vaccinium corymbosum) which are the top two most common cultivars planted in the Northeast.
During the first year (2006), screened cages will be constructed in the field around the plants. Enclosed cages consisting of insect screen attached to a wooden frame are to be constructed around plants to prevent mixing of treatments and to prevent other pollinators from reaching blossoms. During the second (2007) and third (2008) years, hornedfaced bee population density will be evaluated for two successive seasons.
Current recommendation for apple blossom pollination utilized hornedfaced bees is 300 – 400 females per acre. Recommendations for commercial production of blueberries are 870 plants per acre. We would like to determine what recommendation of hornfaced bee density is required to successfully pollinate an acre of blueberry plants. Using the recommendations that are available for hornfaced bees for apple pollination and blueberry plants per acre, we determined that one hornfaced bee should be capable of pollinating three blueberry plants giving a 1 bee : 4 plants ratio. Three bee population density treatments: 1. low (100 hornedfaced bees/acre); 2. medium (200 bees/acre); and 3. high (400 bees/acre), will be evaluated in this research project. Netted cages will be constructed to maintain the low (1 bee : 9 plants), medium (1 bee ; 4 plants) and high (1 bee : 2 plants) treatment population densities. Cages for the low density will be constructed to contain 2 bees and 18 plants (1 : 9 ratio); the medium density will have 2 bees and 8 plants (1 : 4 ratio) and the high density will contain 2 bees and 4 plants (1 : 2 ratio). Each bee population density will be replicated three times inside separate netted cages on the farm. Three branches per plant will be randomly selected that have a minimum of 5 fruiting buds and blossom number recorded. After pollination has occurred the screen will be removed from the field cages to prevent shading of the plants for proper growth and development. Ripe fruit will be picked weekly over the season, with the fruit from each sample being counted and weighed. Blossom number will be compared to fruit number and weight to determine efficiency of pollination as a result of the bee population density treatments.
Data will be analyzed using analysis of variance using the General Linear Model (GLM) procedure of SAS. Data from this component will provide indications of density requirements and allow for recommendations of hornfaced bee density requirements for blueberry production. This study will be repeated for two years to provide data that allows for recommendations of hornfaced bee use and population density requirements for blueberry production.
Hornfaced Bees Cultivar Preferences
Honeybees have definite preferences among blueberry cultivars which require blueberry growers to add more hives to a planting to ensure pollination of non-attractive cultivars (‘Elliot’, ‘Jersey’) increasing production costs. A greenhouse study will be used to determine cultivar preference of 6 major blueberry cultivars utilizing hornfaced bees.
During the first year (2006) two netted cages will be constructed inside the WVU greenhouse and six cultivars, 3 plants per cultivar, will be obtained and selected based on recommendations for honeybee cultivar preference which are very attractive, moderately attractive or poorly attractive to honeybees. The six cultivars that have been selected for evaluation are: ‘Rubel’ and ‘June’ (highly attractive); ‘Duke’ and ‘Bluecrop’ (moderately attractive); and ‘Elliot’ and ‘Jersey’ (poorly attractive. During the second (2007) and third (2008) years cultivar preferences will be evaluated for two subsequent seasons. During the fourth year (2009), an ‘Establishing a Blueberry Plantation’ workshop will be conducted at the West Virginia University, Division of Plant and Soil Sciences Agronomy Farm. This workshop will show how to properly develop and install a blueberry plantation along with use and sustainable management of hornedfaced bees for blueberry pollination to individuals interested in becoming a small or medium sized commercial grower.
Two netted cages will be used inside a greenhouse. The first cage will be used for isolation of the blueberry plants from pollinators to ensure that flowers remain unpollinated. The second cage will be used for pollination of the blueberry plants with one active hornfaced bee inside. Three branches per plant will be randomly selected that have a minimum of 5 fruiting buds and blossom number recorded. Once the 6 blueberry cultivars have a minimum of 2/3 of the blooms open and ready for pollination, they will be randomly placed into the second tent for 4 one-hour bee exposure periods in a single day. During the four one-hour bee exposure periods, blossom visit by the bee to each cultivar will be observed and recorded for bee efficiency (number of blooms visited per hour) and cultivar flower preference. After exposure to the hornfaced bee, the plants will be removed and placed back randomly into the first tent to remain isolated from pollinators for the rest of the growing season for berry development. This will be repeated three times with 3 different sets of the 6 cultivars. Ripe fruit will be picked weekly over the season, with the fruit from each sample being counted and weighed. Blossom number will be compared to fruit number and weight to determine efficiency of pollination as a result of the cultivar preference treatment. If hornfaced bees have cultivar preference, then this should be seen in the number of blossom visits and the number of berries that develop.
Data will be analyzed using analysis of variance using the General Linear Model (GLM) procedure of SAS. Data from this component will provide indications of density requirements and allow for recommendations of hornfaced bee density requirements for blueberry production. This study will be repeated for two years to provide data that allows for recommendations of hornfaced bee use and cultivar preference for blueberry production.
Blueberry Grower Evaluation of Hornfaced Bee Use
Sustainable agriculture methods emphasize on-farm resources and natural biological cycles and controls. Such methods are often more affordable to smaller and limited-resource farmers than are more capital-intensive methods. To determine the sustainability and acceptance of the hornedfaced bee as an efficient alternative or supplemental pollinator, highbush blueberry growers need to have an opportunity to use and evaluate the pollinator. During the first year (2006), a survey will be developed in conjunction with the WVU Extension Service and sent out to 100 targeted highbush blueberry growers (considered to be small or medium sized productions) in the Northeast to identify interested participants of using hornfaced bees as a sustainable pollinator. During the second year (2007), hornedfaced bees, housing materials and a ‘Use and Sustainable Management of Hornfaced Bees for Blueberry Crop Production’ bulletin (developed in conjunction with the WVU Extension Service) will be given to 25 of the identified growers interested in evaluating hornfaced bees as a blueberry pollinator. During the third year (2008), a second run of evaluation of hornfaced bee by the same 25 growers that used the hornfaced bees in 2007 will be conducted. During the fourth year (2009), a final evaluation survey will be sent out to the growers to determine production results and if they will continue use of hornfaced bees. Data will be collected for the two years on berry yield (number and weight) three randomly selected branches from a total of three plants. Propagation of bees will be also be recorded for the two years including the number of empty nesting tubes in the spring and number of empty nesting tubes in the fall. Data will be analyzed using analysis of variance.
Information from the population density and cultivar preference components would not be included in the initial bulletin given to the growers due to the projects being performed concurrently. Information from the population density and cultivar preference components coupled with information gathered from the commercial growers will be used to develop the an updated version of the ‘Use and Sustainable Management of Hornfaced Bees for Blueberry Crop Production’ bulletin to be made available to all commercial growers
Milestone 1, 2, 3 and 4.
A comprehensive list was developed of 100 commercial blueberry growers in the Northeast that are classified as small to mid-sized U-pick operations will be generated using state extension agencies. A survey was developed in conjunction with the WVU Extension Service and sent out to 100 targeted highbush blueberry growers identified as interested participants of using hornfaced bees as a sustainable pollinator with initial information of the benefits of use. From the original 100 growers, 25 were to be selected for a two year evaluation trial. There were three major setbacks in this project which inludec a key individual death, 2007 April freeze, and mite contamination resulting in undermining this research project. The first setback was the death of Dr. Thomas McCutcheon in September of 2007. At the time of this project, T. McCutcheon was working on his Ph.D. which involved developing the comprehensive list of growers, survey, and survey analysis to identify growers for participation. This information was finally recovered late in 2008. The survey was completed and sent out with responses returned but not analyzed for participation. Surveys were then analyzed and 25 participants were selected from the developed database. Hornfaced bee kits were prepared and current bee condition evaluated. This evaluation included cutting open paper tubes which overwinter the dormant bees. Upon cutting open the tubes for evaluation, an infestation of pollen mites (Chaetodactylus krombeini) were found in the nearly all of the research population of hornfaced bees. It was decided that bees were not to be sent out to growers to prevent any spread of mites. There were enough non-contaminated bees to begin developing a new population that was mite-free as well as enough bees for three grower evaluation trials instead of the expected 25. The three growers ranged in location (WV – 15 minutes from Morgantown, PA – 1 hour from Morgantown, and NY – 6 hours from Morgantown) but were similar sized in production. All three growers received a personal visit along with a evaluation hornfaced bee kit which contained 100 hornfaced bees (male and female), new empty nesting tubes for females to lay eggs for next year, nesting tube environmental protection box and a mounting post. All three growers were contacted when the bees were to be emerging and expressed that there were small ‘non-bee insect-like things’ emerging from the tubes. It was determined that these tubes were also contaminated with pollen mites and all three growers were informed to remove all supplied hornfaced bee pollination equipment from the fields and destroyed. All three growers complied with orders. Research was currently being conducted with the assistance of Dr. Yong-Lak Park at West Virginia University to develop methods to prevent contamination and reduce the risk of the pollen mite to the hornfaced bee. This research has developed a clean population of bees that could possibly be utilized for evaluation in future research. Due to the delay in identifying grower participants and contaminated hornfaced bees, Milestones 2, 3 and 4 were not completed for this project. Also, in 2007, the entire crop of blueberries was lost on the McConnell Berry Farm where the cultivar preference and density research was to be conducted to the April freeze that affected the U.S. During the 2008 season, bees were found to be contaminated with mites which also halted the cultivar preference and density requirement research for this project.
Three publications resulted from this research project.
White, J., T. P. West, P. Tobin, and Y.L. Park. 2009. Assessment of Potential Fumigants to Control Chaetodactylus krombeini (Acari: Chaetodactylidae) Associated with Osmia cornifrons (Hymenoptera: Megachilidae). J. Econ. Entomol. 102(6):2090-2095.
West T.P. and T.W. McCutcheon. 2009. Evaluating Osmia cornifrons as Pollinators of Highbush Blueberry. Inter. Jour. of Fruit Sci 9(2):115-125.
Park, Y.L., V. Kondo, J.B. White, T.P. West, B. McConnell, and T. McCutcheon. 2009. Nest-to-Nest Dispersal of Chaetodactylus krombeini (Acari: Chaetodactylidae) associated with Osmia cornifrons (Hymenoptera: Megachilidae). Jour. of App. Ento. 133: 174-180.
Information was also provided on hornfaced bee pollination for blueberries for inclusion in:
SARE and NRAES. 2010. SARE Handbook 11, NRAES-186. Managing alternative pollinators for beekeepers, growers and conservationists. SARE – College Park, MD; NRAES – Ithaca, NY.
Additional Project Outcomes
Impacts of Results/Outcomes
This research was devastated by three major factors; death of a key individual with the project, mite contamination and the 2007 April freeze. The survey supplied information that a large percentage of growers understand that pollination is an issue with blueberry production and would be very willing to participate in a pollination study with alternative pollinators such as hornfaced bees. This research also provided key information that mite infestation is a bigger issue than what is currently presented in the research literature. The hornfaced bee still has a lot of potential to be a highly valuable alternative pollinator for small to medium sized u-pick blueberry growers.
No economic analysis was conducted for this project.
No farmer adoption was achieved with this project. There is a high level of interest in utilizing hornfaced bees for blueberry pollination for u-pick operations.
Areas needing additional study
This project needs more additional studies to determine if there is a blueberry cultivar preference and also the required bee density for blueberry pollination. Additional research needs to be conducted on mite management of hornfaced bees to provide clean populations for evaluation, research and commercial pollination use.