13 The Future of Mason Bees
The future of BOBs
Interest in using mason bees for orchard pollination is growing as both the industry and scientific community recognize their potential. Commercial suppliers are making mason bees more widely available, and new research continues to improve recommendations for their sustainable management. Mason bees are especially appealing to researchers and growers alike because of their strong performance as early-season pollinators in fruit orchards. Additionally, scientists see value in using mason bees to better understand how different bee species respond to pesticide exposure—something that honey bees, the current standard for testing, don’t always accurately represent.
CLIMATE CHANGE
Climate change is making spring weather more unpredictable, with increased chances of rain, cold snaps, and shifting bloom times. This uncertainty makes it harder for growers to coordinate with beekeepers on when to bring in managed honey bee colonies for pollination. Mason bees offer a flexible alternative. Growers can manage mason bee populations themselves or work with a consultant, and bee emergence can be timed by controlling when they are removed from overwintering/refrigeration. For example, a grower with both cherry and apple orchards can release the mason bees from the same overwintering population weeks apart to match each crop’s bloom period. Many growers also stagger bee releases within the same orchard to protect against poor weather, which might otherwise delay foraging and nesting. This level of control gives growers a more adaptable and resilient strategy for ensuring pollination under increasingly variable spring conditions.
RISING COSTS OF MIGRATORY HIVE RENTALS
Rising honey bee hive rental costs are prompting more growers to explore alternative pollination strategies, including the use of mason bees. While honey bees remain essential to global agriculture, beekeepers continue to experience unsustainably high colony losses—estimated at 55% last year—due to factors like parasitic mites, pesticide exposure, and limited forage. At the same time, demand for pollination services is growing, putting additional pressure on an already strained industry. Studies suggest that in the near future, the need for commercial pollination may exceed the supply of healthy honey bee colonies. To keep pace, growers and researchers alike are turning to innovative solutions. Incorporating mason bees into managed pollination systems helps diversify the pollinator portfolio, offering a more resilient and cost-effective option to ensure reliable pollination of spring-blooming crops—even as challenges to honey bee health persist.
CHALLENGES TO OVERCOME
Despite the growing interest in mason bee pollination, the industry still faces important constraints. Currently, many mason bees used in managed systems are sourced through wild trapping—a practice that can disrupt native pollinator communities and increase the risk of spreading regionally isolated pests and pathogens, such as the Houdini fly or chalkbrood, across geographic boundaries. One major driver of wild trapping is the poor recovery of mason bee offspring from certain agricultural landscapes, where short bloom windows and exposure to agrochemicals can limit reproductive success. However, Pennsylvania offers a promising model for sustainable mason bee management. The state’s agricultural landscape—dominated by small, diversified farms surrounded by natural habitat—has long supported strong populations of both wild and managed pollinators. Many growers in the Northeast, including Pennsylvania, already rely less on rented honey bee colonies and instead benefit from the pollination services of wild bees. Protecting and enhancing these communities is both an ecological priority and an economic strategy. In fact, research and field experience have shown that mason bees can be successfully managed and recovered from conventionally managed orchards in Pennsylvania, offering a scalable alternative to wild trapping and a more sustainable path forward for the industry.
VALUE OF MASON BEES FOR FUTURE RISK ASSESSMENT FRAMEWORKS
concept box:
1. The diversity and exposure routes of solitary bees
Traditional pesticide risk assessments rely almost exclusively on the honey bee (Apis mellifera), under the assumption that it sufficiently represents exposure and sensitivity across all bee species. However, solitary bees, which comprise the majority of bee biodiversity, exhibit very different life histories and exposure routes. For example, many solitary bees nest underground or in soil-lined cavities and provision their larvae with pollen, which exposes them to pesticides via soil contact and contaminated nest materials—exposure routes not adequately captured by honey bee testing regimes. These distinctions mean that honey bee–based risk models may overlook important pathways of pesticide exposure that affect solitary bee health.
2. Mason bees as practical and ecologically relevant model species
Several cavity-nesting solitary bees, particularly within the genus Osmia (e.g., O. bicornis, O. cornifrons, O. lignaria), are commercially available and well-suited to risk assessment studies. Their nesting behaviors—such as collecting soil or constructing mud-collars—facilitate semi-field and field testing designs. Moreover, Osmia species provide a model for multiple exposure routes, including ingestion and contact across life stages. Because of their life-history differences and varied sensitivity to chemicals, they can offer more comprehensive insights into non-target effects on solitary bees. In fact, regulatory bodies like EFSA have started recommending O. bicornis and O. cornuta as complementary test species when evaluating plant protection products.
3. Why honey bees are not always suitable surrogates
Honey bees live in large, socially complex colonies with division of labor, extensive foraging ranges, and progressive feeding of larvae—traits vastly different from solitary bees. Consequently, the timing, duration, and pathways of pesticide exposure can differ significantly . For instance, soil-based exposure and child provisioning via pollen—common in solitary species—are absent in honey bee colonies. Additionally, differences in metabolism and detoxification processes mean that sensitivity to agrochemicals may not align across species. While honey bees can serve as a conservative baseline, reliance on them may mask unique risks to non-Apis taxa, underscoring the importance of incorporating solitary bee species like mason bees into pesticide risk frameworks.
