For thousands of years, humans have relied on the European honey bee to pollinate agricultural crops. Now, wild North American bees are getting a second look.
ON A HOT, MID-JUNE AFTERNOON, I follow a caravan of vehicles as they pull over to the side of a dusty road in Walla Walla County. Opening my car door, I notice a hum like distant traffic yet the fields surrounding us are quiet and sweet with blooming alfalfa.
The drone grows louder as farmer Mike Ingham leads us toward a gray patch of ground on a nearby hillside. Within a few steps, we’re engulfed by swarms of alkali bees—hundreds of thousands of iridescent-striped bees, crawling out of holes in the soil, taking flight, and buzzing our ears. I fight an urge to run but he calmly reassures us they’re not aggressive.
The “bee bed” we’re observing is something absolutely unique to this little corner of southeast Washington—the only place in the world where farmers successfully manage native alkali bees, Nomia melanderi, for use as crop pollinators, specifically for producing alfalfa seed.
In return for building attractive nesting grounds for the bees, growers in the Touchet-Lowden-Gardena area are rewarded with 50 percent higher yields of alfalfa seed per acre than other producers. In fact, 25 percent of the nation’s alfalfa seed crop is grown here, which is then sold to raise alfalfa hay, the fourth largest agricultural crop in the United States. Hay, in turn, feeds cattle who produce beef and milk for cheese and other products.
Ingham ’78, third generation alfalfa seed grower and one of only about a dozen in the Walla Walla Valley, invites us to take a closer look at his bee bed. Like an alien moonscape, the bare ashen soil is rutted from runoff and densely dotted with small holes that lead to the females’ nests, eight to ten inches below ground. The busy insects seem to ignore our presence as they fly in and out, digging little dirt piles, and poking their antennae out the openings.
“This relationship between alkali bees and alfalfa is a novel association—they didn’t co-evolve together,” says Ingham. He is referring to the fact that some North American bee species did evolve unique tactics for pollinating native plants like blueberries, tomatoes, squash, and pumpkins.
In the United States, there are more than 4,000 wild bee species, which, along with honey bees, play an important role in pollinating agricultural crops. Unlike honey bees, however, most wild species are solitary and don’t live in communal hives. Seventy percent of these are ground-nesters like the alkali bee, while the other 30 percent prefer cavities such as hollow twigs or holes in wood.
As ancient residents of the Pacific Northwest, alkali bees naturally gather in arid areas with damp, salty soil such as stream banks or salt flats. Once established, the bees will maintain their “neighborhood” for years as long as there is a ready supply of pollen and nectar.
And, come each June, the young bees emerge from their holes in pursuit of mates. Once bred, the females have only six weeks to build a new nest, procure pollen, and raise a brood before they die. As it turns out, that six weeks coincides perfectly with the Walla Walla alfalfa bloom.
It wasn’t always this convenient, says Ingham. The farmland, which receives minimal rainfall, was originally ditch-irrigated for wheat and hay production, and provided only a small alfalfa seed crop on the side. The turning point came with the legendary research efforts of Washington State University entomologists Herman Menke and Carl Johansen.
It was Menke who, in 1949, discovered that alkali bees could be of economic value.
“The ditch banks were moist and bees were digging nest holes in them. Menke realized they were pollinating the alfalfa and helped us begin to commercialize it,” says Ingham.
Menke’s first step was to build an artificial nesting site. Initial attempts were hit and miss—manmade ditches placed at the top of salty slopes to allow water to seep down, or trenches filled with rocks, soil, straw, and water.
Around 1970, Johansen came up with a different approach that more closely mimics the natural groundwater upwelling and alkaline environment the bees prefer. That system helped put the Walla Walla alfalfa seed industry on the map and is still in use today.
“In April, we put four to six tons of rock salt out per acre,” Ingham says. “It seals the soil surface and draws up moisture to make an attractive surface for bees to nest in. Then, we have a sub-irrigation system set up with white PVC pipes buried about 20 inches deep. We pump water into the pipes till around July fourth when runoff from the Blue Mountains dries out.”
Doug Walsh, professor of entomology at WSU Prosser Irrigated Agriculture Research & Extension Center, estimates there are about 40 million alkali bees at work in the Touchet-Lowden-Gardena area each summer.
As the area’s fifth successive WSU bee researcher, Walsh proudly carries on the relationship first established with the alfalfa seed growers by Menke nearly 70 years ago.
Over time, he says the farmers have adapted their culture and depend on WSU leadership to help determine the best ways to control pests while also preserving bees during their critical six-week lifecycle.
Working with members of the Washington Alfalfa Seed Commission, for example, Walsh developed an integrated pest management program for controlling the lygus bug, a harmful insect that infests alfalfa fields at the same time bees are gathering pollen.
Instead of resorting to daytime spraying, growers now apply pesticides only at night when the bees are deep in their holes. And the pesticides they choose are some of the least toxic available. Walsh and graduate student Greta Dupuis are also developing soil temperature sensors to better predict when bees will emerge in the spring, giving farmers a head start on spray reduction.
Studies conducted by Walsh and his predecessors have even influenced state and local laws aimed at protecting the county’s insect partners—especially when the tiny creatures cross roadways. Alkali bees fly low to the ground and can travel up to five miles in search of pollen and nectar, so they are often hit by cars. The faster the speed, the more bees killed.
As a result, Walla Walla County claims to have the only government-created speed limit for an insect, says Walsh. The back roads are adorned with orange traffic signs warning: Speed limit 20 MPH, 8 a.m. till 8 p.m., alkali bee area.
They also have ordinances for pesticide use and one that limits the number of honey bees allowed on property between June and September.
“Honey bees steal nectar and food from the alkali bees,” says farmer Mark Wagoner ’75. “They’re a detriment to alfalfa seed production. They also sting our workers!”
Though honey bees can pollinate alfalfa, they aren’t very good at it, explains Walsh. Alfalfa blossoms have a trip mechanism that bops the bee on the head with pollen. The bee then carries the pollen onto the next flower.
“Honey bees don’t like that, so they learn to chew a hole under the blossom to suck out the nectar,” he says. “It only takes a honey bee worker one day to learn not to get bopped.”
To help ensure a fully-pollinated crop, Wagoner instead relies on imported Canadian alfalfa leafcutter bees (Megachile rotundata). A bit smaller than alkali bees, the leafcutters are cavity-nesters and live in a series of white bee huts set on stilts throughout the alfalfa fields. These miniature high-rise hotels are stacked with bee boards filled with hundreds of holes. Swarms of leafcutter bees hover around the “doorways,” their rapidly-beating wings filling the air with the loud drone we first heard from the car.
WEST OF THE CASCADES, WSU entomologist Dave Crowder and doctoral student Elias Bloom are investigating the role of native pollinators in Seattle’s urban environment. Their Citizen Science Initiative for Bees (CSI Bees) includes the first comprehensive survey of wild bee diversity in the Puget Sound region. In fact, all across the Pacific Northwest, WSU researchers lead the way in pollination ecology and efforts to conserve threatened populations.
By some estimates, pollinators like bees and butterflies produce up to a third of the world’s food supply. Recent studies, however, have shown dramatic declines in many of these species, with some nearing extinction. Once common and widespread, the western bumble bee (Bombus occidentalis) has disappeared from large parts of its former range and other species are following suit.
“Wild bees are affected by the same pesticides, fertilizers, and herbicides that harm honey bees,” says associate professor Crowder. “But most important, they are impacted by the loss of habitat.
“As we convert natural landscapes into agriculture or housing developments, we destroy some of the normal nesting sites,” he says. “Plowing up ground and planting huge monocultures may deplete nesting options for ground-dwelling bees. Clearing forests and other vegetation decreases options for cavity nesters.”
And, although there is scientific value to preserving species, Crowder says on a practical level, we need them to pollinate our food crops and native plants. In fact, for certain crops, wild bees are more effective pollinators than commercial honey bees.
Take the fuzzy bumble bee which has developed the clever trick of “buzz pollination” to release tightly-held pollen grains in cranberries and blueberries. They do this by unhinging their wings from the wing muscles, grabbing onto the pollen-filled anthers, and rapidly vibrating their bodies, something honey bees can’t do.
Studies also suggest that crop yields are improved when both wild and honey bees are present in the same field. Like an insurance policy, the biodiversity provides farmers with more reliable pollination.
Tim Lawrence, associate professor and Island County Extension director in Coupeville, has been keeping bees for 56 years, including a stint as a professional bee wrangler. He shares an inside look at the mysterious ways these insects accomplish their mission.
“Bees are covered with fine feathery hairs that develop a positive electrical charge as the bee flies,” he says. “When they land on a negatively-charged flower, pollen grains will literally jump onto those hairs. The bees then groom their legs and pack the pollen into little baskets on their hind legs called corbiculae and fly back to their nest. During this process, some of the pollen falls off and fertilizes the plant.”
Lawrence says it was recently discovered that when a bee lands on a flower, it reduces the negative charge of that flower, leaving an electrostatic signature that other bees can sense.
“So, you’ll see a bee hovering over a flower and then land on one that indicates it hasn’t recently been visited by other bees and is more likely to offer a pollen or nectar reward.”
Bees also have the help of a floral ultraviolet guidance system. “If you look at a flower under a black light, it shows ultraviolet radiation coming off like landing strips at an airport,” he says. “These lines guide the bee to the nectar and pollen.”
Despite their natural abilities, wild pollinators face an uphill battle against the challenges of climate change, widespread chemical use, and ongoing habitat destruction.
Crowder says the American public is stepping up to help. Citizen scientist groups across the nation have joined forces with federal and academic researchers to gather data and help restore pollinator habitat.
On a local level, he and Bloom launched the Northwest Pollinator Initiative in 2015 to study habitat conservation on small farms in western Washington. The initiative includes CSI Bees, a community information-sharing network where volunteers learn to observe, monitor, and catalog wild bee diversity throughout the region.
“The level of enthusiasm has been through the roof,” Crowder says. “Well over 100 citizen scientists are participating in some of our different projects.”
Crowder and Bloom began their efforts in 2013 when they reached out to Bob Redmond, founder of Seattle nonprofit The Common Acre, who helped locate urban gardens for study and introduced them to local farmers.
Unlike the east side, western Washington farms are typically smaller and more diverse with a mixture of fruits and vegetables that require pollination, such as tomatoes, peppers, squash, strawberries, and apples.
“There is a lot of organic agriculture there—CSAs and farmers markets,” says Crowder. “Farms with diverse crops have plants blooming throughout the whole season which, in turn, helps keep wild bee communities healthy year round.”
Crowder and Bloom have since established a network of about 36 sites for sampling bees—everywhere from downtown Seattle, Tacoma, and Olympia to outlying rural areas.
As a result, they’ve made significant progress in documenting the types of pollinators living around Puget Sound, and are now using the data to develop long-term conservation plans.
Their first step was to team up with P-Patch, a group of Seattle community gardens, where they recently installed a number of “habitat augmentation treatments.”
Each treatment area consists of a patch of bare soil for ground-nesting bees, a section of lavender, lupine, or other flowers, and a bee hotel for cavity-nesters—often, incidentally, painted in bee-attracting bright blue.
CSI Bees volunteers observe these treatments and meticulously record the types of bees, wasps, flies, spiders, butterflies, and other insects that visit. In time, Crowder and Bloom will compare their results to observations made on farms without augmentation. The goal is to try to increase pollination and crop production.
They also hope to verify that the bees will continue flying out to the crops.
“Ultimately, we want bees to increase our food supply. If we provide too nice of a habitat for them, there is the risk that they will have no need to search for pollen and nectar in the fields,” Crowder says. “These enhancements take time, labor, and money, so we have to know if the effort pays off for farmers to invest in it.”
If nothing else, Crowder and Bloom’s efforts have paid off in motivating people.
“Eli is probably asked to give up to 20 presentations per year to everyone from 4-H groups, schools, Master Gardeners, and Girl and Boy Scout troops, to farmers and home gardeners,” says Crowder. “Every year, we put on multiple field days and workshops where we teach people to monitor bees and provide them the tools to augment habitat in their own gardens.
“We’re now starting similar pollinator surveys in the Palouse area of eastern Washington.”
There, among the vast monocultures of wheat, peas, and lentils—which don’t require insects for pollination-—Crowder and Bloom have discovered an unexpected flurry of diversity in the canola fields.
Crowder says canola is one of the few flowering crops in the area that benefits from the service of bees, but they expected most to be honey bees from local beekeepers.
Instead, net samples revealed over 100 different pollinator species including bumble bees, sweat bees, honey bees, mining bees, butterflies, flies—and even a variety of leafcutter bees.
“I was surprised at the diversity,” he says. “There are very few patches of natural Palouse prairie habitat left to support bees, and those that are there must often travel long distances to find a canola field.”