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Small Wonders: The Plight and Promise of California’s Native Bees


A black-tailed bumble bee (Bombus melanopygus) on a taking pictures star (Primula sp.) in Yosemite Nationwide Park. Picture: Michelle Duennes

This story first appeared within the Fall 2020 difficulty of Flora. 

By Emily Underwood

“In 2007, biologist Gretchen LeBuhn found an uncommon winged customer in one in all San Francisco’s metropolis
parks: a black bee with rust-colored fuzz and pale yellow stripes which she and her college students recognized because the California native wool carder bee, Anthidium palliventre.

Coast buckwheat (Erigonum latifolium) rising on the northwestern coast of the Level Reyes Nationwide Seashore. The wool carder bee makes use of fibers scraped from the buckwheat’s tender leaves to line its nest in sand dunes. Picture: Elizabeth Kubey

The bee makes use of its bristled legs to dig a nest in sand dunes, then scrapes hairs from the leaves of coast buckwheat (Erigonum latifolium) to line its nest with tender fluff. Like many different dune-dwelling bees it was as soon as a San Francisco native, sipping nectar from lupine and different coastal scrub wildflowers.

However when builders paved over many of the dunes on the peninsula, the bees misplaced their houses. “They’re little representatives of the historical past of the land,” LeBuhn says, speculating that the few different wool carder bees she’s discovered might dig their nests in sandboxes.

The wool carder bee is only one of many “small wonders” that LeBuhn and her crew at San Francisco State College have discovered within the metropolis’s parks. Even a tiny one-acre park can entice as many as 30-40 native bee species if they’ve a number of flowers and good nesting areas. Planting native wildflowers is especially essential to help the state’s specialist bees, which have developed to want only one or a couple of sorts of vegetation, LeBuhn says: “Folks suppose [pollinator loss] is an terrible and daunting difficulty, however I believe we are able to all assist.”

The roughly 100 or so native bee species that LeBuhn has documented inside San Francisco is roughly half of what she would look forward to finding there, based mostly on surveys in close by Marin County and the East Bay space. Though the peninsula might traditionally have had fewer species, LeBuhn attributes at the least some loss to growth. “San Francisco has fewer bee species than it might if it was wild,” she says. “No one’s going to be stunned by that.”

A wool carder bee (Anthidium palliventre) photographed in a San Francisco metropolis park by one in all biologist Gretchen LeBuhn’s graduate college students, Nevin Cullen.

Like many pollinators, together with bats, birds, butterflies, moths, flies, beetles and small mammals, various California’s wild bee species are beneath risk. One of the best-studied declines are in bumble bees: In 2019, for instance, the California Fish and Recreation Fee voted in favor of itemizing 4 species of California bumble bee beneath the California Endangered Species Act, together with Crotch’s bumble bee (Bombus crotchii), Franklin’s bumble bee (Bombus franklini), Suckley cuckoo bumble bee (Bombus suckleyi), and the western bumble bee (Bombus occidentalis occidentalis).

For different native bee species, knowledge are sparse or nonexistent. “We don’t know what number of species are doing,” says Hollis Woodard, an entomologist at UC Riverside who research the life cycles of bumble bee queens. To start out filling these knowledge gaps, Woodard lately helped launch a scientific consortium referred to as the Nationwide Native Bee Monitoring Community. In the meantime, LeBuhn and her crew at San Francisco State College are working a decades-long neighborhood science effort referred to as The Nice Sunflower Undertaking, by which gardeners throughout the nation report what bee species come to go to.

The declining Suckley’s cuckoo bumble bee. Picture: Hadel Go/CC BY 3.0

Of the roughly 20,000 bee species discovered all through the world and three,600 native bee species in North America, California is house to 1,600. It’s exhausting to overstate the dazzling number of wild bees in California, which CNPS former government director Dan Gluesenkamp describes as “the Amazon Basin of bee range.” Some are tiny, just like the fruit-fly-sized Perdita minima, which pollinates minute desert wildflowers equivalent to whitemargin sandmat (Chamaesyce albomarginata). Others are huge, just like the male Valley carpen- ter bee (Xylocopa varipuncta), a fuzzy golden bee that some scientists confer with as a “teddy bear.”

Not like the social, non-native western honeybee (Apis mellifera), most of California’s native bees dwell solitary life-styles. Some bees nest within the floor in deserted cavities; others, just like the wool carder bee, dig or construct their very own nests. Some shelter inside bushes, others in rock partitions and even deserted snailshells. There are pink, black, and blue bees, and metallic inexperienced “sweat” bees that drink human perspiration.

Regardless of the kaleidoscopic array of native bees, western honeybees have lengthy acquired nearly all of public consideration and analysis {dollars} as a result of they’re so essential to agriculture, says LeBuhn. America Division of Agriculture (USDA) values the entire annual contribution of honeybee merchandise and pollination companies at $700 million. No less than in the USA, nevertheless, the lack of honeybees “is an agricultural difficulty, not a conservation difficulty,” says Woodard. “They’re not native, and so they’re utterly entangled with our agricultural system, many features of which aren’t sustainable.”

Left to proper: A turret-building chimney bee (Diadasia sp.) on chaparral mallow (Malacothamnus fasciculatus); mining bee (Adrena sp.) on Channel Islands tree poppy (Dendromecon harfordii); striped sweat bee (Agapostemon sp.) on Guadalupe Island globemallow (Sphaeralcea sulphurea). Photographs: Kris Ethington

California is the Amazon Basin of bee range.”
– Former CNPS Government Director Dan Gluesenkamp

In the early 2000s, scientists coined the time period “colony collapse dysfunction” (CCD) for a mysterious syndrome that was decimating domesticated honeybee populations. Though scientists nonetheless aren’t positive what causes CCD, they suppose it arises from a mixture of pests such because the varroa mite parasite, illness, poor vitamin, pesticide publicity and different stressors, equivalent to being transported by truck from farm to farm. The syndrome nonetheless poses a serious risk: From April 2019-2020, beekeepers misplaced greater than 40 p.c of their colonies to CCD, the USDA stories.

The plight of managed honeybees raised alarms that native bees is perhaps going through related challenges, says Neal Williams, a pollination ecologist at UC Davis. Though most native bees don’t dwell in colonies like honeybees do, they too are prone to poor weight loss program and lack of habitat, he says.

Defending native bees will be an essential insurance coverage coverage towards the lack of honeybees, Williams and his colleagues have discovered. In a 2002 article within the Proceedings of the Nationwide Academy of Science, for instance, Williams, the late entomologist Robbin Thorp, and conservation biologist Claire Kremen discovered that for natural farms positioned near native bee habitat, equivalent to oak woodlands and chaparral, “free” pollination from native bees was ample to develop even demanding crops like watermelon, which requires as much as 1000 grains of pollen to supply a single melon.

Native squash bees (Peponapis pruinosa) are extremely efficient pollinators for cultivated squash, melons, and different crops.
Picture: Ilona Loser, CC-BY-SA-4.0

Quite a lot of different research have proven that native bees can outperform honeybees in pollination. Bumble bees, for instance, use a messy technique referred to as buzz pollination to vibrate the flower and shake extra pollen free. The approach which seems more practical than honeybee pollination for crops together with tomatoes, peaches, and various native vegetation, amongst them huckleberries and manzanitas.

The standard of pollination — what number of grains of pollen get from the male to feminine elements of a flower — issues for the standard of meals. Effectively-pollinated melons are greater and firmer, apples rounder. Effectively-pollinated cultivated strawberries (descendants of California’s native seaside strawberry, Fragaria chiloensis) are extra completely shaped and redder.

Our agricultural system threatens native and non-native bees alike, says Williams. In California, many small plots with flowering borders have been consolidated into massive, homogeneous zones that present poor bee forage and habitat. A superb instance is CA Route 99 by means of the Central Valley, with its massive swathes of suburban growth crops. “I wouldn’t wish to be a bee there,” Williams says. Crops equivalent to corn and wheat will not be sometimes pollinated by bees, LeBuhn provides, so a traditional corn area doused in pesticides “is about as barren as you may get.”

Most folks like the thought of supporting bees — the query is the best way to do it, says Williams. “I believe {that a} grower, a conservation biologist, a commodity board member would all agree that we want to help native bees, however that’s a reasonably nebulous assertion.”

At UC Davis and Hedgerow Farms, a local seed firm in Winters, California, Williams and postdoc Uta Muller have been testing native wildflower mixes to see that are most engaging to native bees and different pollinators. The crew has planted gridded plots with native wildflowers equivalent to California poppy, phacelia, native sunflowers, and coyote mint. In a laborious course of, they’re now counting and figuring out the native bees that go to every plot as soon as every week, for 9 months. “We run by means of each plot as soon as within the morning, take a fast break in the midst of the day, then repeat the entire thing,” Williams says.

By way of this and former experiments, Williams thinks he’s now received a reasonably good grasp of what vegetation totally different species of bees want. However he’s nonetheless making an attempt to suss out how a lot land a farmer must plant with a purpose to make an actual distinction — “Is it 5 p.c, 10 p.c?”

Working with the Xerces Society, Hedgerow Farms, and different collaborators, Williams in the end hopes to develop pc algorithms that can recommend the very best seed combine for a given function, whether or not that’s supporting uncommon bee species, offering meals for as many various bee species as doable all year long, or supplementing honeybee crop pollination. He’s additionally making an attempt to get the price of seed mixes down. At current, planting a pollinator combine bought from the Pure Sources Conservation Service may cost a little a farmer $500-700 an acre, and he needs to scale back the fee all the way down to a 3rd or a fifth of that, and even much less, he says. One problem is to create seed mixes that not solely swimsuit pollinators, however people, he says. “Folks will say, ‘I wish to help pollinators, however I additionally need issues which are pink, blue and yellow blooming in all three seasons.’”

The native wildflower pollinator seed combine trials at UC Davis Pupil Farm in April 2020. Picture: Williams Lab UC Davis.

Gardeners ought to use native wildflower seed mixes of recognized genetic origin, like these offered at Hedgerow Farms, notes CNPS Director of Biodiversity Iniatives Andrea Williams. When folks plant non-local wildflowers, they run the chance of wiping out native species by means of hybridization. A superb illustration of why native seeds are preferable is the long-lasting Texas bluebonnet (Lupinus texensis). Through the use of bulk seed from out of state, Texas has “hybridized their state flower out of existence — they don’t have any native variation anymore,” Williams says. “We don’t need that to occur to our state flora.”

Not like California’s native vegetation, which have been extensively mapped due to organizations like CNPS, there’s scant details about what number of of California’s native bee species are distributed all through the state, and thus how local weather change, growth and different elements are affecting them, LeBuhn says. “It’s superb how a lot we don’t know.” A method folks will help scientists is to take part in neighborhood science initiatives just like the one she is working, the Nice Sunflower Undertaking. The challenge wants extra volunteers, notably in rural areas, she says. Gardeners also can discover lists of bee-friendly vegetation on CNPS’s Calscape.org and on the Xerces Society web site.

Habitat loss is barely one of many many threats that bees face, Neal Williams notes. Neurotoxic pesticides like neonicotinoids could also be interfering with bees’ capacity to forage, whereas pathogens like varroa mites and nosema illness, and environmental elements like drought exacerbate bees’ susceptibility to illness. Identical to in folks, Williams says, “If we stress ourselves, then illness or parasites have a higher impression.” To higher perceive how California’s bees are responding to pesticides, Williams is measuring pesticide residues within the pollen that bees accumulate, which he’ll use to develop a map of publicity over area and time. At UC Riverside, Woodard is working lab experiments to check how pesticides have an effect on the brains of bumble bee queens.

UC Riverside entomologist Hollis Woodard and her crew are finding out bumble bee queens within the Sierra Nevada. Picture courtesy of Hollis Woodard.

Excessive within the Sierra Nevada, Woodard and her crew are additionally finding out what bumble bee queens must thrive at totally different levels of their life cycle, with a purpose to higher perceive how they’ll reply to local weather change and discover methods of supporting the bees all year long. It’s an pressing query, as local weather change seems to be driving many bumble bee species worldwide towards extinction: In a February 2020 Science research of 66 bumble bee species in North America and Europe, for instance, researchers discovered that as temperatures have climbed, the possibilities of a bumble bee inhabitants surviving in any given location has dropped by a median of 30 p.c.


A manzanita wonderland

California is a hotspot for manzanita range, with roughly 100 species and subspecies of manzanita, 59 of that are so uncommon they solely develop in a single wild place. There’s hardly a extra Californian shrub, rising from coast to mountaintop, with many species’ survival tied to fireplace, fog, and launched pathogens. When planting manzanita to help native bees, it’s a good suggestion to make use of native species, says CNPS Director of Biodiversity Initiatives Andrea Williams.

Left to proper: Hoary manzanita (Arctostaphylos canescens ssp. canescens) Picture: Morgan Stickrod. The uncommon Santa Margarita manzanita (Arctostaphylos pilosula) Picture: garmonb0zia/iNaturalist CC0. Endangered Mount Diablo manzanita (Arctostaphylos auriculata) Picture: Al Kordesch.

Bumble bee queens spend a lot of their lives alone, wintering underground and rising within the spring. In lots of areas of California, observers can spot the queens feeding on early-blooming native vegetation like manzanita (Arctostaphylos spp.) as early as February; by shivering their flight muscle tissue the queens can elevate their physique temperatures in chilly climate.

A yellow-faced bumble bee (Bombus vosnesenskii) on manzanita (Arctostaphylos sp.) in Sierra Nationwide Forest. Picture: Erica Sarro

As soon as the queens have fattened up, they begin flying low over the bottom in a zigzag sample, searching for a cavity to nest in. After making a thimble-sized pot of honey and a small mound of pollen as a meals reserve, they begin laying eggs and incubating them. When a larva hatches, a queen bumble bee will regurgitate meals into its wax pot “like a mama chicken,” Woodard says. About two weeks later, the larvae chew their approach out and grow to be the primary staff.

If solo bumble bee queens don’t get the meals that they want in early spring, or can’t discover a nest, they gained’t have the ability to produce a colony. “It’s a very tenuous level within the life cycle,” Woodard says. She needs to know the way these intrepid queens get by in elements of California the place manzanita doesn’t develop, and the way they deal with the unpredictable climate of early spring, when there will be flowers in bloom one heat day, and snow the subsequent.

Woodard’s and her crew’s cautious observations of queen bumble bees all year long underscore simply what number of totally different sorts of flowering vegetation are wanted to help a colony, she says. “It’s not simply early-blooming vegetation, however the full season that issues, during the tip.”

For gardeners and others who wish to help native bee populations, rising the variety of flowering vegetation which are accessible beginning in February and lasting all the best way into the autumn can present crucial help, she says. “Whenever you scale that out to all the opposite pollinators, you suppose, ‘Oh my gosh, we want flowers in every single place.’”

UC Riverside PhD pupil Natalie Fisher in Yosemite Nationwide Park. Picture: Hollis Woodard

Emily Underwood is the Publications Editor for CNPS.  

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