In celebration of Pollinator Week, June 17-23, we’re saluting Mason Bees, a cadre of pollination experts that joined our tree growing team this spring. As first-time hosts of mason bees, we’ve learned a lot along the way. In support of pollinators, we’re pleased to share our experience in working with mason bees in our effort to sustainably increase Dolgo crabapple seed yields. They’re the source of hardy rootstocks for ornamental crabapples destined for JFS customers in cold climates.
This spring, we took delivery of 300 mason bees cocoons and tucked them into newly built, bright blue “company housing” in the middle of our Dolgo crabapple orchard. The new residents began hatching within days, and quickly got to work, buzzing among the clouds of emerging white blossoms.
New Plant Development Specialist Jim Donohoe spearheaded the effort and shares some of the highlights and challenges of establishing a resident colony of mason bees. Here in Oregon, we’re fortunate to have great pollinator resources including the Oregon Bee Project and a professorship at Oregon State University devoted to Pollinator Health. Jim found Dr. Andony Melathopoulosand his PolliNation Podcast to be very helpful in his research, and influential in his decision to enlist mason bees for our Dolgo crab project.
“Our goal is to produce enough Dolgo crabapple seed to meet our needs for cold hardy rootstock,” Jim explained. “Originating in Siberia, their disease resistance and hardiness in temperatures as low as -40 °F. makes Dolgo a great rootstock for our ornamental crabapple production. Obtaining enough seed to meet our production needs has always been a challenge, so we looked into ways to increase pollination.
“After some research and attending a beekeeping club meeting, we chose to work with smaller, native mason bees rather than the larger, honey-producing European honeybees that are social insects that live in hives,” he added.
“Mason bees are solitary insects that construct their nests in hollow cavities. They’re named for their habit of using mud or other ‘masonry’ products. They don’t make honey, but they visit a wider variety of plants and are more effective pollinators. They’re very efficient pollinators that carry pollen on their hairy bellies and transfer it directly to the stigma of the flowers. They’re disease-resistant and hardy, and one mason bee can do the work of 100 honeybees!”
Mason bees are active from early spring to midsummer, Jim explained, and they pollinate a wide range of flowers, including early flowering fruit trees.
“Mason bees and Dolgo crabapples are a perfect match for our project,” Jim continued, “as they have similar climatic requirements and compatible hatching and blooming periods. The Dolgo crab flowers provided abundant and nutritious food for the mason bees this spring as they helped us increase the pollination rate and seed yields.”
Jim’s report about the mason bee project, written for JFS staff, is shared here for those interested in improving pollination in their nursery, orchard or home landscape.
Establishing Mason Bees for Dolgo Crabapple Seed Production
By Jim Donohoe | New Plant Development Specialist
In preparation for the 300 mason bee cocoons purchased from a reputable supplier in Utah, we chose a sunny and sheltered spot near the Dolgo orchard. Small wooden bee houses containing several rows of bamboo tubes, mounted on posts at three feet off the ground, provide nesting sites for the bees. A tray of moist clay is maintained nearby for use as nesting material.
Adult mason bees began flying around within a few days of their release! Thanks to their gentle and docile nature, they haven’t bothered JFS employees.
Because mason bees are attracted to pheromones left behind from previous nesting seasons, we’ll use a synthetic pheromone for the first couple of seasons to make sure the bees will keep using the homes we provide for them.
The lifecycle of a mason bee begins in early spring when adult mason bees emerge from their cocoons and mate. Males die shortly after mating, leaving females to build their nests and lay their eggs. Each egg and a pollen ball for food is sealed into a chamber with mud. Eggs hatch into larvae, which feed on the pollen and grow inside the chambers. They spin cocoons around themselves and transform into pupae which develop into adult bees. They then hibernate inside their cocoons, waiting for warmer spring temperature that signal the right time to emerge.
This project is sustainable and cost effective because we can harvest and overwinter mason bee cocoons in cold storage. Harvesting and overwintering them is a simple process that can help build and maintain our own healthy and productive bee population. This will enable us to manipulate the release of bees year after year, timed to meet our pollination needs both in the seed orchards and our new plant development pollination projects.
Please keep your eyes peeled for small bee houses scattered throughout seed orchards and experimental blocks on the farms. Always something abuzz at JFS!
Basic steps for harvesting and overwintering:
- Remove tubes from bee house in late summer or early fall, after bees have stopped flying. Store in a breathable bag in a warm place until the temperatures drop below 50°F.
- Open tubes and gently remove cocoons. A knife or scissors can be used to cut the tubes.
- Discard any cocoons that are sunken, C-shaped, or have holes. These are signs of fungal infection, parasitic wasps, or other problems.
- Wash cocoons in a solution of cool water and bleach (1/4 cup bleach per gallon of water) for about two minutes to kill any fungal spores or mites. Rinse and dry cocoons.
- Store cocoons in a sealed container with some ventilation holes and a damp sponge in the refrigerator. Ideal conditions are 30-40°F and 60-70% humidity.
- Check cocoons periodically and make sure the sponge is moist but not wet. Replace sponge if it gets moldy.
- In the spring, when temperatures are consistently above 50°F, place the cocoons in a PVC incubation tube near the bee house. The bees will emerge and start their new cycle.
