Progress report for OW24-004
Project Information
The mason bee (Osmia) industry remains small compared to other managed bee industries (i.e. honey bees, bumble bees, and alfalfa leafcutting bees). A major limiting factor of industry growth is slow bee propagation and having only a small set of target crops (primarily orchard crops). By expanding the number of managed mason bee species targeting specific crops that would benefit from diversified pollination (e.g. berry crops), we can open new crop markets for bee producers, and help alleviate pollination deficits for growers. Managed bee population growth also needs to be more sustainable. One primary issue facing the industry is unintended negative consequences on wild bee populations through extractive harvesting of mason bees from wild populations. We need to develop more sustainable ways of propagating bees, either on farms or in other landscapes, that reduce impacts to wild populations. Here, we will test management strategies for bee propagation of two newly managed Osmia species targeted for berry crop pollination (O. ribifloris and O. bruneri). This will include propagation efforts along an urban-wildland gradient through collaboration with community members, and propagation on commercial berry farms. With the aim of building up already managed populations, instead of harvesting from wild bee populations. Outcomes of this work include sustainable bee management recommendations for bee producers and early testing of two newly managed bee species for berry crop pollination.
Research Objective 1: Develop strategies for farming Osmia ribifloris and O. bruneri to increase propagation while reducing extractive pressures on local bee populations.
Research Objective 2: Test the use of O. ribifloris and O. bruneri as managed pollinators at commercial berry farms.
Education Objective 1: Develop a community outreach program to both increase community member involvement in bee propagation strategies and community education about solitary bees.
Education Objective 2: Facilitate Farmer-to-Farmer educational outreach days to educate peers about the use of Osmia bees for crop pollination.
Education Objective 3: Create technical publications on the use of Osmia ribifloris and O. bruneri for crop pollination, and best management practices.
Education Objective 4: Create hands on video demonstrations of Osmia management techniques, available for free online.
| 2024 | 2025 | 2026 | ||||||||||||||||||||||||
| Objective | Detail | Apr | May | Jun | Jul | Aug | Sept | Oct | Nov | Dec | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sept | Oct | Nov | Dec | Jan | Feb | Mar | |
| Research | 1 | O. ribifloris ranching | x | x | ||||||||||||||||||||||
| O. bruneri ranching | x | x | ||||||||||||||||||||||||
| Create pollen reference library | x | x | x | x | ||||||||||||||||||||||
| Identify pollen from nest provisions | x | x | x | |||||||||||||||||||||||
| Manage bees for the next season | x | x | x | x | x | x | x | x | x | x | ||||||||||||||||
| 2 | Release O. ribifloris at blueberry fields in UT and OR, monitor nesting rates |
x | x | |||||||||||||||||||||||
| Release O. bruneri at raspberry fields in UT and OR, monitor nesting rates |
x | x | ||||||||||||||||||||||||
| Identify pollen from nest provisions | x | x | x | |||||||||||||||||||||||
| 1 & 2 | Data analysis and manuscript preparation | x | x | x | x | x | x | x | x | x | x | x | ||||||||||||||
| Education | 1 | Community outreach program for bee propagation | x | x | x | x | ||||||||||||||||||||
| 2 | Farmer-to-Farmer outreach days | x | x | |||||||||||||||||||||||
| 3 | Technical publications on Osmia management | x | x | x | x | x | x | x | ||||||||||||||||||
| 4 | Video demonstrations on Osmia management | x | x | x | x | x | x | x | x | x | x | x | x | |||||||||||||
Cooperators
- (Researcher)
- - Producer
- - Technical Advisor - Producer
Research
Objective 1: Develop strategies for farming O. ribifloris and O. bruneri to increase propagation while reducing extractive pressures on local bee populations (2024)
27 sites on the Wasatch Front in northern Utah (Salt Lake City region) were selected along an urban-wildland gradient. Sites were selected by developing a network of community volunteers who are interested in helping to propagate bees. We targeted volunteers who have ample preferred forage in their yard or nearby. Preferred forage for O. ribifloris includes blueberries (Vaccinium), redbud (Cercis), mahonia (Berberis), manzanita (Arctostaphylos), and Oregon grape (Mahonia) (Cane and Sipes 2006; pers. observation). Osmia bruneri foraging preferences are more generalized (e.g. Frohlich and Tepedino 1986; pers. obs.). We reached out to community members through various community news outlets, including fliers at local gardeners’ markets. We then visited properties in Spring 2024 to assess the suitability for propagation, including the presence of floral resources, and lack of chemical pest management activities.
Nesting shelters were placed at each site so that they were protected from rain or sprinkler systems and provided morning sun (e.g., southeast aspect and not shaded by structures or thick vegetation). Each nesting shelter contained ~160 nesting cavities (slight variation with the number of reeds included; Fig. 1). In late-March, we released Osmia ribifloris adults at each site at sex ratio of 1.5 males to 1 female. We released a range of adult numbers (between 55 and 150 adults; mean = 62.78 ± 23.47 S.D.) at each site depending on the availability of bees and the predicted suitability of the site, with more bees added to sites predicted to be good for the bees based on available preferred forage. Nesting shelters were checked every 1-2 weeks and completed nests were counted to monitor nesting success at each site until the end of May.
Figure 1. Nesting shelters developed by K. Clark (Nativebees.com) used in this study.
All O. ribifloris nests were collected at the end of May and stored in a storage shed (not environmentally controlled, open air), until late November where the nesting shelters were processed, and all cocoons were removed and counted. Any cocoons with clear parasitism or disease were removed. All cocoons were then placed in cold storage (4°C) at the PIRU. In February 2025, we x-ray all collected nests at the PIRU to identify any additional incidents of parasitism and identify dead or weak bees, which are identifiable by no or very little fat bodies, which can be seen on an x-ray.
In early June, we released ~40 Osmia bruneri at the same sites as O. ribifloris. However, we quickly realized that our O. bruneri population that we have managed at the USDA ARS Pollinating Insects Research Unit (PIRU) for many years had unexpectedly high overwintering mortality. We do not know the cause of this mortality, but it left us with a decimated managed population, and very few adults emerged from their cocoons across all sites in this study and several other studies being conducted at the PIRU in 2024. This is highly unusual for this species, as we have generally had a lot of success managing this species. We are currently working to identify potential causes of this high mortality so that we can try again in 2025.
Using the BeeShiny tool created by researchers at Pennsylvania State University, we calculated landscape metrics at 1km radii around each 2024 site. This included percent developed habitat, an estimate of urbanization, preferred nesting habitat, and spring forage. Preferred nesting habitat and spring forage were determined using the same methods as described in Koh et al., 2015 (https://www.pnas.org/doi/full/10.1073/pnas.1517685113). We then tested if there is a relationship between nesting rate and these landscape features using a generalized linear model.
Objective 2: Test the use of O. ribifloris and O. bruneri as managed pollinators at commercial berry farms. (2025)
This objective will be completed in 2025.
Objective 1: Develop strategies for farming O. ribifloris and O. bruneri to increase propagation while reducing extractive pressures on local bee populations (2024)
All 27 sites had O. ribifloris nesting, though with varying rates of “return” (bee cells created in 2024 that will be adults in 2025). Percent return is presented here as the number of O. ribifloris cells collected, divided by the number of O. ribifloris initially released at that site x 100. Percent return ranged from 20% - 591% (mean = 185% ± 143 S.D.). A return rate of greater than 100% is necessary for bee ranching, as bee managers need to get back more bees than were initially put out to build a sustainable business. 19 out of the 27 sites had >100% return rates, and 9 out of 27 had >200% return rates. We will repeat ranching in 2025 at the top 12 sites for bee returns to see if these sites remain consistently good year-to-year.
Unfortunately, none of the landscape features we measured were significantly correlated with increasing bee return rates (p > 0.05). We will continue to explore other landscape features to see if any patterns emerge, and we will have further discussions with the bee managers on this project (Kimball Clark, Evan Sugden, SK Pelch) to identify what landscape features they use to pick sites and if any of these can be quantified in a way to assist other bee managers in picking locations for ranching.
Objective 2: Test the use of O. ribifloris and O. bruneri as managed pollinators at commercial berry farms. (2025)
This objective will be completed in 2025.
Research Outcomes
Education and Outreach
Participation Summary:
Education Objective 1: Develop a community outreach program to both increase community member involvement in bee propagation strategies and community education about solitary bees. We worked with 25 community members in order to propagate mason bees on their properties. We worked closely with these community members to explain mason bee biology and the pollinations benefits they provide to agricultural crops and natural/wild flowering plants. We also conducted two workshops, one at the Sundance Nature Alliance, and the other at Lomond View Nursery to teach community members about mason bees.
Education Objective 2: Facilitate Farmer-to-Farmer educational outreach days to educate peers about the use of Osmia bees for crop pollination. The Farmer-to-Farmer outreach days are currently being organized for late Spring/early Summer 2025 in UT and OR. We also presented information about using mason bees as managed pollinators for fruit production to 78 fruit growers in Utah at the Utah Horticultural Society Fruit Growers Annual Meeting in January 2025.
Education Objective 3: Create technical publications on the use of Osmia ribifloris and O. bruneri for crop pollination, and best management practices. This has not been completed yet.
Education Objective 4: Create hands on video demonstrations of Osmia management techniques, available for free online. This has not been completed yet.
Education Objective 1: Develop a community outreach program to both increase community member involvement in bee propagation strategies and community education about solitary bees. All 25 community members that we worked closely with in 2024 were enthusiastic about participating again in 2025.
Education Objective 2: Facilitate Farmer-to-Farmer educational outreach days to educate peers about the use of Osmia bees for crop pollination. At the Utah Horticultural Society Fruit Growers Annual Meeting, we used the SARE survey, and 77% of respondents (n = 22) said "yes" to the question: "in the next year I am likely to use some aspect of this project to increase the operation's diversifications." We take this as a positive sign that fruit growers in Utah are interested in diversifying their managed pollinators, including the use of managed mason bees on their farms.