What Native California Plants Are Best For Attracting Pollinators?

Bug Squad By Kathy Keatley Garvey December 18, 2018

What Native California Plants Are Best For Attracting Pollinators?

That's a question often asked.

Now for answers.

Ola Lundin, first author

Ola Lundin, first author

Neal Williams, professor and Chancellor’s fellow

Neal Williams, professor and Chancellor’s fellow

Kimiora Ward, project scientist (Photos: Kathy Keatley Garvey)

Kimiora Ward, project scientist (Photos: Kathy Keatley Garvey)

Three pollination ecologists from the University of California, Davis, have just published their research, “Identifying Native Plants for Coordinated Habitat Management of Arthropod Pollinators, Herbivores and Natural Enemies,” in the Journal of Applied Ecology. It details what plants proved most attractive to honey bees, wild bees and other pollinators, as well as what drew such natural enemies as predators and parasitic wasps.

“I hope this study can inform selection of plants that support pollinators and natural enemies without enhancing potential pests,” said lead researcher and first author Ola Lundin, a former postdoctoral fellow in the Neal Williams lab, UC Davis Department of Entomology and Nematology and now a postdoctoral fellow in the Department of Ecology, Swedish University of Agricultural Sciences, Uppsala.

He and co-authors Williams, professor of entomology and a Chancellor's Fellow at UC Davis; and project specialist Kimiora Ward of the Williams lab conceived the ideas and developed the methodology for the research project.

“Planting wildflowers is a key strategy promoted nationally to support wild and managed bees,” said Williams. “Successful adoption of these plantings in agricultural landscapes will require that they not only support pollinators but that they also avoid supporting too many pests. Plant selection going forward will need to balance multiple goals of pollinators pest management and other functions. This research is a first step on the path to identifying plants that will meet these goals."

The trio established 43 plant species in a garden experiment on the grounds of the Harry H. Laidlaw Jr. Honey Bee Research Facility at UC Davis. They selected plant species that were drought-tolerant; native to California (except for buckwheat, Fagopyrum esculentum, known to attract natural enemies and widely used in conservation biological control); and, as a group, covered a range of flowering periods throughout the season. (Download the plant species here.)

The Great Valley gumplant (Grindelia camporum) was one of the 43 plants tested. Here a cukoo bee Triepelous Epeolus, forages on a blossom. (Photo by Kathy Keatley Garvey)

The Great Valley gumplant (Grindelia camporum) was one of the 43 plants tested. Here a cukoo bee Triepelous Epeolus, forages on a blossom. (Photo by Kathy Keatley Garvey)

Every week, over a two-year period during the peak bloom of each plant species, they engaged in three different sampling techniques: netting wild bees, observing honey bees, and vacuuming insect herbivores, arthropod predators and parasitic wasps.

“For early season bloom, Great Valley phacelia (Phacelia ciliata) was a real winner in terms of being attractive for both wild bees and honey bees,” Lundin said. “Elegant Clarkia (Clarkia unguiculata) flowers in late spring and was the clearly most attractive plant for honey bees across the dataset. The related Fort Miller Clarkia (C. williamsonii) was also quite attractive for honey bees and had the added benefit that a lot of minute pirate bugs visited the flowers.”

Lundin said that common yarrow (Achillea millefolium)“attracted “attracted the highest numbers of parasitic wasps but also many herbivores, including Lygus bugs.”

“In general a lot of parasitic wasps were found on Asteraceae species (the daisy family) and this was a somewhat surprising result considering that they have narrow corollas, and for parasitic wasps relatively deep corollas that can restrict their direct access to nectar. Under the very dry conditions in late summer, Great Valley gumplant (Grindelia camporum) and Vinegarweed (Trichostema lanceolatum) both performed well and attracted high numbers of wild bees.”

The team found that across plant species, herbivore, predator and parasitic wasp abundances were “positively correlated,” and “honey bee abundance correlated negatively to herbivore abundance.”

The take-home message is that “if you're a gardener or other type of land manager, what you'd likely prefer would be a mix of some of the most promising plant species taking into account their individual attractiveness for these arthropod groups, plus several more factors including costs for seed when planting larger areas,” Lundin said.

“Plant choice can also depend on how you weigh the importance of each arthropod group and whether you are interested in spring, summer or season-long bloom,” Lundin added. Those are some of the questions that the Williams lab plans to explore in future projects.

Phacelia californica was among the 43 plants tested. Here a bumble bee, Bombus vandykei, and a honey bee, Apils melllifera, share a blossom. (Photo by Kathy Keatley Garvey)

Phacelia californica was among the 43 plants tested. Here a bumble bee, Bombus vandykei, and a honey bee, Apils melllifera, share a blossom. (Photo by Kathy Keatley Garvey)

“It was fascinating for me to see how these and other plants flowering in the latter part of the summer not only survived but also seemed to enjoy themselves in the heat without water for months!” Lundin quipped.

Williams praised the “uniquely capable team that came together.”

“Ola is an emerging leader in considering integrated management of pests and pollinators and Kimiora is a known expert in developing regionally-relevant plant materials to support pollinators,” Williams said. “They and some talented UC Davis undergraduates--notably Katherine Borchardt and Anna Britzman--compiled a tremendously useful study.”

The overall aim of the study “was to identify California native plants, and more generally plant traits, suitable for coordinated habitat management of arthropod pollinators, herbivores and natural enemies and promote integrated ecosystem services in agricultural landscapes,” the researchers wrote.

More specifically, they asked:

  1. Which native plants among our candidate set attract the highest abundances of wild bees, honeybees, herbivores, predators, and parasitic wasps,

  2. If the total abundances of arthropods within these functional groups across plant speacies are related to the peak flowering week, floral area, or flower type of the focal plant species, and

  3. If the total abundances of arthropods within these functional groups are correlated to each other across plant species.

“A first critical step for design and implementation of multifunctional plantings that promote beneficial arthropods while controlling insect pests is to identify suitable plant species to use,” the authors wrote in their abstract. “We aimed to identify California native plants and, more generally, plant traits suitable for the coordinated management of pollinators (wild bees and honey bees), insect herbivores and arthropod natural enemies (predators and parasitic wasps).”

At the time, the Laidlaw grounds included nearly 50 bee colonies: some 20 to 40 honey bee colonies, and eight managed research colonies of the yellow-faced bumble bee, Bombus vosnesenkii.

The project drew funding from the USDA Resources Conservation Service, USDA Agricultural Marketing Service, USDA National Institute of Food and Agriculture and a Swedish foundation for scientific research, the Carl Tryggers Stiftelse for Vetenskaplig Forskning.

Phacelia campanularia was one of the 43 plants tested in the UC Davis research garden. Here a honey bee sips nectar from a blossom. (Photo by Kathy Keatley Garvey)

Phacelia campanularia was one of the 43 plants tested in the UC Davis research garden. Here a honey bee sips nectar from a blossom. (Photo by Kathy Keatley Garvey)

These are some of the 43 plants tested in the UC Davis research garden. This is an illustration from the research paper. (Photos by Ola Lundin)   https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=28959

These are some of the 43 plants tested in the UC Davis research garden. This is an illustration from the research paper. (Photos by Ola Lundin)

https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=28959

Your Call's One Planet Series: Why are flying insects dying off at alarming rates?

KALW Radio     By Rose Aguilar and Malihe Razazan    October 22, 2017

Listen to a great commentary on a recent study showing decline in flying insect populations and pollinator declines in general. Speaking are Dr. Neal Williams (UC Davis) and Dr. Dave Goulson (University of Sussex)


The Monday October 23, 2017 broadcast of Your Call: One Planet Series

LISTEN: http://kalw.org/post/your-calls-one-planet-series-why-are-flying-insects-dying-alarming-rates#stream/0

Insects make up about two-thirds of all life on Earth, but since 2006, honey bees and other pollinators have experienced rapid population declines. New research has found that the flying insect population in nature reserves across Germany has plummeted by 75 percent in the past 25 years.

Scientists warn that this trend can lead to an ecological Armageddon. What is causing this? And what can be done to stop it? Join our next Our Planet series on Your Call, with Rose Aguilar, and you.

Guests:

Neal Williams, professor of Pollination and Bee Biology in the Department of Entomology and Nematology at UC Davis

Dave Goulson, biologist, conservationist, and professor of Biology at the University of Sussex

Web Resources:

LA Times: Wild bees are least abundant where they're most needed, study says

The Guardian: Warning of 'ecological Armageddon' after dramatic plunge in insect numbers

http://kalw.org/post/your-calls-one-planet-series-why-are-flying-insects-dying-alarming-rates#stream/0

Here's the Buzz That Might Change How We Think

Bug Squad - Happenings in the Insect World   By Kathy Keatley Garvey    4/7/14

Talk about a good insurance policy.

Researchers at Michigan State University (MSU) just published an article in the Journal of Applied Ecology that indicates that blueberry growers who invest in nearby wildflower habitat to attract and support wild bees can increase their crop yields.  They're saying that the cost of planting a habitat for wild bees can pay for itself in four years or less.

"Other studies have demonstrated that creating flowering habitat will attract wild bees, and a few have shown that this can increase yields," MSU entomologist and co-author Rufus Isaacs said in a press release. "This is the first paper that demonstrates an economic advantage. This gives us a strong argument to present to farmers that this method works, and it puts money back in their pockets." 

"This is HUGE news," said pollination ecologist Neal Williams, associate professor of entomology at UC Davis, who was not involved in the study.  "This is the first study to quantify pollination benefit as a result of habitat planting adjacent crops.  It also works through the economics of the implementation of the the habitat and accrued economic and yield benefit over time.  Fantastic stuff."

This is right up Willilams' alley, er, hedge row. He and his colleagues are exploring the role of wild native bees, honey bees and other managed species as crop pollinators and the effects of landscape composition and local habitat quality on their persistence. His research on pollination spans the disciplines of conservation biology, behavioral ecology and evolution. One of his primary research foci is on sustainable pollination strategies for agriculture. This work is critical given ongoing pressures facing managed honey bees and reported declines in important native pollinators such as bumble bees. 

Williams' research has taken him from eastern Pennsylvania and New Jersey to California's Central Valley.  "A continuing goal is to provide practical information that can be used to improve the long-term stability of pollination for agriculture in California, as well as promote pollinator conservation and management," Williams says.  In addition to work in agriculture, he is also studying how habitat restoration affects pollinator communities and pollination.  

Earlier California studies, involving Clare Kremen of UC Berkeley, Neal Williams and other colleagues, showed that wild bees make honey bees better pollinators; that is, the presence of wild bees makes the honey bees work harder.

Regarding the MSU study, the research team planted surrounding bueberry fields with a mix of 15 native perennial wildflowers, hoping to increase the wild bee population and thus improve pollination in the blueberry fields. 

And yes, that's exactly what happened. 

"In the first two years as the plantings established, we found little to no increase in the number of wild bees," Isaacs related in the press release  "After that, though, the number of wild bees was twice as high as those found in our control fields that had no habitat improvements."

To quote from the press release: "Once the wild bees were more abundant, more flowers turned into blueberries, and the blueberries had more seeds and were larger. Based on the results, a two-acre field planted with wildflowers adjacent to a 10-acre field of blueberries boosted yields by 10-20 percent. This translated into more revenue from the field, which can recoup the money from planting wildflowers."

Isaacs was quick to point out that the researchers are not suggesting that growers cease using honey bees for pollination services.  But with 420 species of wild bees in Michigan alone, he says, it makes sense to attract the "free" wild bees. Indeed, it does.

This study could have major implications for not only research in California, but nationwide.

Read at...

Visit the Kathy Keatley Garvey Bug Squad blog at: http://ucanr.org/blogs/bugsquad/

Parasites, Pesticides and Pollination

Bug Squad - Happenings in the Insect World   By Kathy Keatley Garvey   10/15/13

What are the indirect effects of parasites and pesticides on pollination service?

Ecologist Sandra Gillespie, a postdoctoral researcher in the Neal Williams lab, UC Davis Department of Entomology and Nematology, will present the results of her research at a departmental seminar from 12:10 to 1 p.m., Wednesday, Oct. 16 in 122 Briggs Hall. It will be recorded for later posting on UCTV.

“Whether in natural or...

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Visit the Kathy Keatley Garvey Bug Squad blog at: http://ucanr.org/blogs/bugsquad/

Congrats to "The Bee Team"

Bug Squad - Happenings in the Insect World   By Kathy Keatley Garvey  4/25/13

Congrats to “The Bee Team” at the University of California, Davis.

The one-of-a-kind team, comprised of five Department of Entomology faculty members, received the coveted team award from the Pacific Branch, Entomological Society of America (PBESA), for their collaborative work specializing in honey bees, wild bees and pollination issues through research, education and outreach.

Their service to UC Davis spans 116...

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Visit the Kathy Keatley Garvey Bug Squad blog at: http://ucanr.org/blogs/bugsquad/
Visit the Kathy Keatley Garvey website at: http://kathygarvey.com/

Why This Honey Bee Research Is So Important

Bug Squad - Happenings in the Insect World   By Kathy Keatley Garvey   1/10/12

They're on to something.

Definitely.

An international research team has been researching honey bee pollination of almonds in the three-county area of Yolo, Colusa and Stanislaus since 2008, and what these scientists have discovered is astounding.

The bottom line: Honey bees are more effective at pollinating almonds when other species of bees are present.

The research, “ 

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Visit the Kathy Keatley Garvey Bug Squad blog at: http://ucanr.org/blogs/bugsquad/
Visit the Kathy Keatley Garvey website at: http://kathygarvey.com/

The Importance of Pollinators

Bug Squad - Happenings in the Insect World   By Kathy Keatley Garvey 12/3/12

It's a brief appearance but the message is important.

Pollination ecologist Neal Williams, assistant professor of entomology at UC Davis, appears briefly in a segment on native pollinators produced by America's Heartland. The show is now airing throughout the country. (Watch video)

Reporter Sarah Gardner of...

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Visit the Kathy Keatley Garvey Bug Squad blog at: http://ucanr.org/blogs/bugsquad/

Visit the Kathy Keatley Garvey website at: http://kathygarvey.com/