A third of the human diet relies directly or indirectly on biotic pollination. Pollinators contribute 9.5% to the global agricultural output, or about $153 billion. In the U.S., the value of pollination services has been estimated at $18.9 billion for honeybees and $3 billion for native bees. Without bees, the flowers of bee pollinated crops will abort or will set small, misshaped, flavorless and quickly perishable fruit. In addition, many wind pollinated crops have better yields when bees augment the pollination process. Currently, honeybees are decimated by a combination of pests, pathogens, and stresses as result of poor management and overexploitation. However, wild bees can successfully pollinate commercial crops by themselves if some farm land is managed as bee habitat with an abundance of floral and nesting resources. Wild bees not only provide free pollination but are active in inclement weather and are more effective in vectoring pollen between flowers than honeybees. This is the second phase in a three-year project that deals with the monitoring of the bee population on two farms on which were installed plots with abundant floral provisioning. The overall goal of this project is to determine the change in the diversity and density of native bees when plots with floral provisioning are installed. With the knowledge of how to conserve and restore the native bee habitat and the costs needed to do so, farmers will be better equipped in avoiding the lack of or expensive pollination triggered by the ongoing honeybee crisis. Besides a ready supply of on-farm pollination services, by actively managing a population of plants rewarding to native pollinators throughout the year, growers will have a healthy and diverse population of pest predators, reduced farm soil erosion, irrigation water loss and fertilizer runoff, as well as more windbreaks, weed suppression, etc.
Numerous organizations throughout North America are working on conserving and encouraging pollinators, with great emphasis on honeybees. Valuable research is being done on bee biology, habitat restoration, pollinator plants, plant pollinator interactions, bee diversity, bee pests and diseases, synergistic and sublethal pesticide effects on bees, etc. However, despite the significance of the subject matter and the information available, the Northeast and Mid-Atlantic regions have no programs investigating the effects on the native bee populations as result of installing floral provisioning plots on farms. Moreover, the farmers in these regions need to have demonstration farms that will be how-to guides for providing forage and nesting resources for the native bee population. These types of projects can incorporate all the available data and give a full perspective to the farmer on the volume of work and financial investment needed for accomplishing pollination sustainability. This project-l represented the second phase in a three year project and it dealt with managing and monitoring the research plots. The desired goal of this research project is to assess if there is a change in the diversity and density of the bee population on farms as a result of installing floral provisioning plots. For a better understanding the environmental impact of our project, the bee population was monitored bi-weekly. For achieving consistent and nonbiased results, only the pan trapping method was used. In 2009, at Dickinson College Farm and Penn State Southeast Agriculture Research and Extension Center were installed two 25’ by 100’ plots with floral provisioning. Although the later site was not specified in the 2009 NESARE contract, this was possible due to significant educational discounts on plant materials and some in-house funds. In 2010, the goal was to maintain the research plots and continue to monitor the general trend in the diversity and density of the bee population. To ascertain the costs and benefits of installing floral provisioning on farms, we will be factoring in the time and funds invested in the initial installation and yearly maintenance. The returns will be determined by the rate of which the diversity and density of the population of native bees is changing.
Besides maintaining the research plots weed free on an as-needed basis, the objective in 2010 was to assess the change in the density and diversity of the bee population at Dickinson College Farm in Boiling Spring, PA, and at the Penn State Southeast Research Center in Manheim, PA.
On both farms, every two weeks from 7:00 am to 5:00 pm, the bee population was monitored. The monitoring process consisted in deploying brightly colored (white, yellow, and blue), 3.25 ounce bowls. The bowls were filled with soapy water, which has minimum surface tension. A number of twenty bowls were used on each farm, with 10 bowls being placed adjacent to the floral provisioning plot and other 10 bowls placed 300 meters away and towards the middle of the agricultural field. On each transect the bowls were placed 5 meters apart, ensuring that their colors alternated. At the end of the day or the very next morning, the bee specimens trapped in the soapy water were collected and placed in vials with 70% alcohol. At the end of the season the specimens were washed, dried, pinned, and labeled. Easy-to-identify species were identified in-house, while harder-to-identify ones were taken to Sam Droege, biologist at USGS Patuxent Wildlife Research Center, for expert identification. Once all bee specimens were identified, an Excel database was generated. The results were analyzed to determine the trend in the density and diversity of the bee population on each farm. For a complete list of all bee species collected in 2009 and 2010 see Excel file # 1.
Based on the number of samples collected, the following are the results regarding the trend in the density and diversity for the bee population for each of the farms involved in this study: Density Boiling Springs, PA – Compared to 2009, the overall number of bee specimens captured in 2010 increased with 92% for plot I (floral provisioning), 164% for plot II (300 meters away from floral provisioning plot and towards the center of the agricultural field), and 127% for the overall—see Excel file # 2 for more info; – Compared to 2009, the average number of bee specimens captured per each collection event in 2010 increased with 125%—see Excel file # 3 for more info; Manheim, PA – Compared to 2009, the overall number of bee specimens captured in 2010 increased with 118% for plot I (floral provisioning), 344% for plot II (300 meters away from floral provisioning plot and towards the center of the agricultural field), and 241% for the overall—see Excel file # 2 for more info; – Compared to 2009, the average number of bee specimens captured per each collection event in 2010 increased with 152%—see Excel file # 3 for more info; Diversity Boiling Springs, PA – Compared to 2009, the overall number of bee species captured in 2010 increased with 169%—see Excel file # 4 for more info; – Compared to 2009, the species richness in 2010 increased with 313%—see Excel file # 4 for more info; Manheim, PA – Compared to 2009, the overall number of bee species captured in 2010 increased with 145%—see Excel file # 4 for more info; – Compared to 2009, the species richness in 2010 increased with 409%—see Excel file # 4 for more info;
The monitoring results indicate that the density and diversity of the bee population had significantly increased on both farms. When both farms are compared, the farm located in Manheim, PA, registered a higher increase. This might be because historically the Manheim farm has been more intensive cultivated. On this farm the agronomic crops are more prevalent, which has resulted in less floral provisioning for the native bees. In addition, the Manheim farm employs a more conventional spraying system. In contrast, the farm located in Boiling Springs, PA, has virtually no agronomic crops. The horticultural crops are cultivated on small fields that often are separated by flower strips. Also, the Boiling Springs farm employs an organic-like approach when controlling pest and disease pressure. For these reasons, it is possible that the Boiling Springs farm had a more stable bee population from the beginning. As result the change in the density and diversity could have been not as high as for the Manheim farm.
Education & Outreach Activities and Participation Summary
The Principal Investigator of this project had presented some of the preliminary results at the following events: 1) 2010 Mid-Atlantic Fruit and Vegetable Convention – approx. 75 growers; 2) 2010 Summer Garden Experience – approx. 50 MGs and landscapers; 3) 2010 Discovery Day @ Penn State Southeast Research Center – approx. 45 legislators and/or their aids; 4) Various farm visits – approx. 12 farmers.
In 2010, the only costs incurred with these floral provisioning plots were those for suppressing the weed pressure. At each farm in spring was needed 8 hours for removing the weeds. Later in the season, manual weed removal was used on an as-needed basis. For maintaining the plots relatively weed free throughout the year, we estimate that was needed 16 hours of labor ($160) for each farm. The following represent the costs incurred for establishing in 2009 one 100 ft x 25 ft floral provisioning plot: 1) Mechanized labor for tilling and leveling the ground 2 hours @ $25 per hour $50 2) Manual labor for installing the deep plugs 40 hours @ $10 per hour $400 3) Manual labor for maintaining in the growing season 40 hours @ $10 per hour $400 4) 4-inch deep plug perennials $.80 each x 50 pcs x 23 $920 Total: $2,220 The cost of the 4-inch deep plug perennials is the single largest expense. For minimizing their costs, farmers have the option to establish floral provisioning habitats from seed. This however, may have lower rate of plant establishment and more weed pressure.
Most farmers are very interested in installing floral provisioning plots. However, the costs of establishing such plots from deep plugs are still very high. On the other hand, establishing them from seeds results in less consistent results, mainly due to an increase in the weed pressure. Currently, Penn State in collaboration with NRCS is looking into what are the best practices for establishing floral provisioning plots on farms.
Areas needing additional study
More information is needed regarding what are the most important pollinator species for each crop grown in the Northeastern U.S. The phenology of these pollinators needs to be studied in detail. For each commercially important pollinator species is necessary to determine what non-crop floral resources are visited. This information can be used for better determining what non-crop flowering plants need to be established on a given farm.