Blue Orchard Bee Shows Promise As An Alternative Pollinator In Almonds

blue orchard bee

Blue orchard bee is easier to work with than honeybee. Photo courtesy of Derek Artz, USDA-ARS.

Call it mason bee or blue orchard bee. Osmia lignaria is known by a few names, but it may soon be serving a singular purpose as a valuable alternative pollinator in almond orchards, particularly for smaller growers.

As bearing almond acreage continues to climb in California, the costs and availability of honeybees for pollination remain a challenge for growers. Losses from Colony Collapse Disorder seem to have stabilized, but the inventory of colonies for that critical spring pollination period hasn’t increased significantly.


Alternatives are needed.

A potential solution could be the incorporation of the blue orchard bee in pollination programs, either alone or in conjunction with honeybees. While we’re not yet there in terms of sufficient commercial populations for widespread use in tree fruit and nut orchards, indications are they have real promise.

What’s The Difference?
Blue orchard bees are among a small number of species that nest in holes, rather than hives. With blue orchard bees, every female — about a third to a quarter of each brood — is a queen, which produces a brood without assistance of others.

According to Dave Hunter, owner of Crown Bees in Woodinville, WA, honeybees and blue orchard bees (AKA mason bees) work differently.

“Mason bees are out in early morning to begin pollen gathering. honeybees come out around 10 a.m. and have stripped all the local fields of pollen within about three hours. Then they are off to other areas in a two-mile radius looking for more while the mason bees stay close to home,” he says.

“Mason bees go a maximum of 300 feet. They are generally up and working earlier. They have no honey so they have to work. That’s all they really do, and they’re working more pollen than honeybees do as a result,” he says.

The two bees’ pollen gathering strategies differ as well. Hunter says a honeybee works a branch, loads up, goes back to the hive — and then returns to the same branch to get more.

“honeybees know a good thing when they find it,” he says. “Mason bees are more ADD. They go everywhere from tree to tree gathering dry pollen on their abdomens. As a result, pollen is falling off everywhere. They pollinate everything.”

Another big difference is the numbers used in an orchard for pollination. A honeybee hive may contain 30,000 bees.

“With 1,000 mason bees, 600 males and 400 females, you can get the same results as those 30,000 honeybees,” Hunter says.

Do-It-Yourself Pollinators
Blue orchard bees are probably a little more work for growers, at least in the beginning. Rather than rent colonies as with most honeybees, most growers can actually rear the blue orchard bees themselves or have a custom service do it.

“This is not like placing a honeybee hive and walking away,” Hunter says. “You’re building your own permanent colonies. You’re maybe spending 10 to 15 minutes to put up four nesting houses per acre with zip ties on branches. There are 400 females per acre. That’s 400 to 500 holes in the ‘nest’ for the bees,” he says.

The grower initially keeps the bees, still in their cocoons, in a cooler, and gets them ready to emerge them by warming them up a few days before bloom in small containers. Those containers, with preemerged bees, are positioned into each acre when needed for bloom.

He estimates growers need to invest about 45 minutes annually for each colony, putting the bees out, protecting them when they spray, and cleaning out the wood trays at the end of the year. After the bees make their nests, the grower gathers the cocoons and places them in a temperature-controlled container to protect them from mites and disease.

Blue Orchard Bee Benefits
While they do take some adjustments to your normal pollination program, blue orchard bees do appear to have benefits.

“Blue orchard bees are really nice to work with,” says Steve Peterson, an entomologist for AgPollen LLC in Waterford, CA, where he’s been researching them intensively since 2007. “With honeybees you need a bee suit and a smoker to keep them calm. Blue orchard bees rarely sting and you don’t need protective clothing to work with them. There’s just less to manage compared to honeybees. You don’t have to feed them or treat for pests.”

More importantly, research has shown increased yields when blue orchard bees are used in conjunction with honeybees.

Paramount Farming Company has been experimenting with blue orchard bees for 8 years. Director of pollination operations Gordon Wardell says they have used the bees in conjunction with honeybees on 80 acres. He’s seen positive results in Paramount’s almond orchards when the two pollinate together, although he emphasizes that things are still firmly in the research phase.

“We have found they work very well with honeybees. We can put one honeybee colony in an orchard along with several hundred blue orchard bees and get as good or better pollination as we do with two colonies of honeybees. They form a friendly competition and appear to have different foraging behaviors so they complement each other very well,” he says.

Unfortunately, scaling up for large blocks of acreages has been a problem.

“We know the blue orchard bees do a good job at pollination. The challenge for us is there just aren’t enough of them and the price is just too high for commercial pollination at the numbers we need,” Wardell says.

Challenges Still To Address
Indeed, availability in sufficient numbers seems to be the main stumbling block limiting wider adoption of blue orchard bees in large orchards. Inventories are built mainly by trapping wild bees and by designing breeding programs.

Efforts are being made to build and maintain healthy populations of pollinators, including blue orchard bees, by creating a more beneficial habitat in California’s almond orchards, but there’s still work to do.
The hope is once a colony is established, the bees will reproduce at a rate that delivers at least as many bees as you had the year before. That’s been a challenge so far.

“It’s a process to try to figure out how to raise the amount of bees we need because you can’t trap enough in the wild. We have to use the bees we have and then start propagating them. One of the big challenges is that blue orchard bees only have one breeding cycle a year. With honeybees, the queen is laying eggs and every 21 days a new adult emerges,” Wardell says.

According to Hunter, the costs for Crown Bees’ blue orchard bees run about $500 per acre for a thousand bees, which includes hands-on training during the first year. Depending on the number of bees you’re buying, costs could run as high as $1 a bee.

“If we can get the price down under 15 cents a bee it will be more doable on big acreages,” Peterson says.

Another challenge is the blue orchard bee is very susceptible to insecticide and fungicide sprays.

“honeybees process the food they give to their young. A lot of the pesticides get filtered out in the process,” Wardell says. “Blue orchard bees directly feed the pollen they collect to their larvae, so they’re very susceptible to pesticides. Orchards that have to spray during bloom may have problems with these bees.”

“They stay in the orchard for six weeks. You might have six weeks of bloom and we know during that time you will spray pesticides. It’s a given. We encourage you to go into the orchard before you spray and cover them, and to spray in the evenings when the bees aren’t as active,” Hunter says.

Adoption From The Bottom Up
So with all of these challenges, are blue orchard bees a viable pollinator for almond growers? William Kemp, center director of USDA’s Red River Valley Agricultural Research Center in Fargo, ND, says depending on the grower, the answer is absolutely yes.

“From the standpoint of whether this bee has potential, there’s no question about it. Some growers have tens of thousands of acres. That’s a different problem. But a grower with a hundred acres can do this and can afford it now,” Kemp says.

Its use is already fairly widespread, particularly in areas where people can’t get honeybees, he points out.

So in the future, will blue orchard bees be used as a standalone pollinator or is it best partnered with honeybees?

“Both,” Kemp says. We need to enlarge our pollinator portfolio. There are niche markets that are available and the blue orchard bee is emerging from a specialty market emphasis and being evaluated at a larger scale.

Kemp believes the use of the blue orchard bee will continue to expand as the economics make sense.

“I can’t envision in my lifetime that we will ever see sufficient honeybee numbers. Therefore it’s wise to look at alternatives or supplementary technologies. That’s precisely what this is,” he says. “In terms of proof of concept, that’s settled in my mind. What we need to work on are engineering, production, appropriate technologies from an ecological perspective, and management plan alternatives people can implement and make them available and scale up.”