ILLUSTRATIONS BY MARGO RIVERA-WEISS
This article grew out of a conversation between Helen Krayenhoff, Edible East Bay’s garden editor and co-owner of Kassenhoff Growers, and Laura Ward, a volunteer research assistant for Professor Gordon Frankie at the UC Berkeley Urban Bee Lab (helpabee.org and The Urban Bee Lab on Facebook). Laura helps with the lab’s Farming for Native Bees project, which utilizes their 12 years of groundbreaking research on native bees in urban gardens to construct native bee habitats on conventional and organic farms in Brentwood. She also works at Berkeley Horticultural Nursery, which happens to be one of the nurseries where Professor Frankie buys his bee plants. Helen read in the Berkeley Hort newsletter about the nursery’s Bee-Friendly Project, which has to do with bees and neonicotinoids, a pesticide suspected in the recent alarming decline in worldwide bee populations. Since this topic is of great concern to Helen, she decided to ask Laura about this and other things pertinent to bees and home gardening.
HK: Tell us more about the Farming for Native Bees project.
LW: The purpose of the Farming for Native Bees project is to study the restoration of native bee habitat on farmlands in an effort to assist farmers with pollination options in the face of honey bee decline. We study the specific bee-plant relationships and we’re also looking at bee behavior and nesting necessities. The bee-attracting plants have the added benefit of increasing biodiversity on the farms and attracting other beneficial insects.
Farming for Native Bees has partnered with eight small farms in Brentwood, some, such as Frog Hollow or Knoll Farms, that you may be familiar with from your local grocers or farmers markets.
Four of the farms are treatment sites, where bee-attracting plants and nesting habitat are added to the farmland. The lab conducts seasonal bee counts to assess and identify the bee population on these farms. The other four farms are control sites, which means that bee counts are conducted without adding any bee habitat to the farms.
The study is now in its fourth year and we’re starting to see some patterns emerge. Initial results suggest that most of the treatment farms have increasing bee diversity each year, whereas the control farms haven’t shown much change over the first few years. This suggests that we’re learning to successfully attract native bees to cropland, which may subsequently aid in the pollination of those crops.
Though we have a long way to go, our goal is to eventually be able to prescribe specific bee habitat to farmers, based on their specific crop type, as a supplemental pollination service to honey bees.
HK: What is the role of bees in our ecosystem?
LW: Well, for starters, one in every three bites of food you eat might not be there were it not for bees. Agriculture relies primarily on the honey bee (Apis mellifera) to pollinate 75 percent of human food crops worldwide¹, so imagine what would happen if they went away. And, as it turns out, honey bees are facing many challenges, including Colony Collapse Disorder, the cause of which remains unknown. But the fact is, it’s not just honey bees that are important in our ecosystem: We live among many wild bees, which often go unnoticed, but are equally important for pollination and maintaining biodiversity.
There are actually about 4,000 known bee species in the U.S. and about 1,600 of them can be found right here in California. Most of these are wild, native bees.2 Honey bees were actually imported from Europe back in the 1600s and I don’t think they were even brought to California until the 1800s. You may be fond of honey bees for their honey, but it’s important to realize that there are many other kinds of bees that help make the world go round.
HK: What challenges are bees facing?
LW: Just like us, bees need a good diet to stay healthy, which for them means having many different types of flowers, and especially native plants, to forage from. Bees also need places to nest: While honey bees are kept in hives, most of our native bees nest underground in soil or in premade cavities in wood. However, land-use changes, including urban expansion and the growth of monoculture farming, have caused the loss of habitats that provide bees with essential forage and nesting material. But bees are also impacted by some of the same things that impact us, like pollution and climate change. Pesticide exposure is also a problem, and not just in agriculture. Urban areas expose bees to pesticides, too. If we curb our pesticide use, our urban home gardens can be a great resource for supporting bee populations. In the Urban Bee Lab, I learned that the diverse gardens of Berkeley, for example, support almost 100 wild bee species. Before applying any pesticide in your home garden, you might want to think about whether you are exposing your local bees to neonicotinoids.
HK: What are neonicotinoids?
LW: Neonicotinoids, or neonics for short, are a widely used class of neurotoxic, systemic insecticides that were introduced to the market around 1990 to control sucking insects like aphids.3 Since they are water-soluble, they travel easily throughout all plant tissues and can also move through soil. They can be applied to plants in a variety of ways, from soil treatments to tree injections and foliar sprays, and are commonly used in agriculture as seed dressings to prophylactically protect crops. They’re a very seductive pesticide because they protect the entire plant, they have low toxicity to humans and they have high toxicity to insects. While this may seem like a good idea for pest control, you have to consider that neonics can’t distinguish between the insects we regard as pests and beneficial insects, such as bees.
Also, you might be surprised to know that neonics aren’t just used in agriculture and horticulture. Pet owners, whether they know it or not, are very likely to be using a neonic called imidacloprid, the active ingredient in Advantage, a popular flea-control product.
HK: How do neonics affect bees?
LW: The fact that neonics are water soluble and systemic means that they wind up in the pollen and nectar of treated plants. Adult bees eat nectar and developing bees are fed nectar and pollen. Certain levels of neonicotinoid contamination can be lethal to bees. For example, just last year 50,000 bumble bees were found dead in a Target parking lot in Oregon; Oregon Department of Agriculture determined that the deaths were directly related to the application of Safari, a pesticide that contains a neonicotinoid called dinotefuran. Granted, the application was in violation of the label instructions because it was applied while the trees were blooming. The whole situation is really sad and disturbing, but on the bright side, Oregon is making some positive changes in response to this incident, including permanent restrictions on the use of some neonics and increased education on pollinator protection.
However, from what I understand, even when neonics are used as directed, the chemicals can still end up in pollen and nectar. The concentrations may not be lethal to bees; but even the sublethal effects,4 which include reduced learning and forage capability, are concerning to me.
It’s a balancing act. Every pesticide has its tradeoffs. And pesticide exposure is only one among many challenges that bees are facing. However, it’s not just the effects of neonics on bees that concern me; I am also concerned about the detrimental effect they might have on other beneficial insects, especially soil dwelling insects that help maintain soil health. It is unfortunate: Pesticides are advertised as the primary cure-all for pest problems, but there are many other solutions for pest management, which also happen to be more environmentally friendly.
You know, Europe recently restricted the use of certain neonics in response to the European Food Safety Authority’s (EFSA) report about their risk to bees. So it’s a little baffling that the U.S. hasn’t followed suit. As it turns out, the EPA has reached similar scientific conclusions as the EFSA, but since the U.S. will not complete the registration review of some neonicotinoids until 2019, it appears that any bans or restrictions will be put off until then, despite the fact that pollinator decline is happening now.
HK: How did you become interested in this topic?
LW: This past September, I read a study published by Friends of the Earth (foe.org/beeaction), which found that 54 percent of common, bee-friendly plants purchased at top garden retailers nationwide contained neonicotinoids. My friend, Lisa Archer, is one of the authors on the report, and after talking with her about their findings, I realized that I knew little about the neonic practices of the growers that Berkeley Hort buys from. And since these plants are used in bee habitat restoration projects as well as our own home gardens, I decided to investigate.
So, I proposed a project to Paul Doty, the president of Berkeley Hort, which we’re now calling the Bee-Friendly Project. It involves providing customers with information about Bee-Friendly gardening, and also identifying which plants at our nursery are guaranteed to be neonic-free. Paul was very receptive to the idea, as it aligns with the nursery’s historic reputation for placing value in biodiversity and healthy ecosystems.
Berkeley Hort buys from over 70 growers, and we were not sure how many would divulge their pesticide practices, but we decided it couldn’t hurt to ask. We feel that if we’re going to market plants as Bee-Friendly, we owe it to our customers to make sure they are not contaminated with neonics. So we sent a questionnaire to all of the growers, asking whether they use neonicotinoids and what plants they’re used on, etc. This article will go to print before we’ve finished compiling our results, so at this point, I can only say that some of our growers are decidedly not using neonics, some are using them but plan to stop, and others do not fit into these two categories. By early March, we should have a better idea of who’s using what, and what plants are safe. We encourage people to visit the nursery and check in on our progress.
HK: What can I do in my own garden to support bees?
LW: The answer is that you can really do a lot.
Flowers, flowers, flowers! I used to think that having a vegetable garden was enough: Who needs flowers? Well, pollinators need flowers! In fact, different bees like different kinds of flowers, and they need flowers that bloom during different periods of the year. So it is helpful to plant a good variety of pollen and nectar resources in your garden, and make sure that a few plants are flowering at all times of year. You can visit helpabee.org to find a list of the best bee plants for California, or ask at your local nursery.
Go organic! And not just for your edibles! Buy organic seeds and starts, whenever possible, so that you can guarantee your plants won’t contain neonics. And if you buy non-organic plants, you might consider asking the nursery whether they or their growers have used neonics on these plants.
Provide nesting opportunities! Most wild bees are ground nesters, and much to my surprise, they cannot nest in mulch! Ground nesters need patches of bare dirt. Other bees are cavity nesters, which means they build their nests in premade cavities in wood. Many nurseries sell premade cavity nests kits for this purpose, but you can also try drilling holes in some logs or tree stumps and placing them in your yard.5
Avoid pesticides! Especially avoid neonicotinoids. There are many ways to control pests without using pesticides. Ask your local nursery how to attract beneficial insects and how to fend off pests in an environmentally friendly manner. The sales staff at Berkeley Hort has great experience dealing with tenacious little buggers, and you can also visit the UC Integrated Pest Management (IMP) website at ipm.ucdavis.edu and read up under “Home, garden, turf, and landscape pests.”
HK: If someone has insecticides with neonicotinoids in them, what should they do with them?
LW: Alameda County residents can safely dispose of pesticides Thursday–Saturday 9am–1pm at Alameda County Household Hazardous Waste: 2100 East 7th Street, Oakland (stopwaste.org). If you are not an Alameda County resident, call 800-CLEANUP to find your household hazardous waste facility. Please, please do not throw pesticides in the trash and do not pour them down the drain.
LW: Ask your local nurseries to provide neonic-free plants. The more places that demand neonic-free plants from their growers, the more growers will be persuaded to stop using neonics. And if we’re tackling this problem at Berkeley Hort, where we buy from over 70 growers, I think it’s totally feasible for other nurseries to tackle as well.
Write to your government leaders to pressure them to ban neonics until further research is done on their environmental safety for pollinators and other beneficial insects. Three good petition resources are:
Tell your friends and neighbors how your garden practices are helping to conserve local, native pollinators and encourage them to do the same! •
BEE FRIENDLY PLANTS
To attract bees to your home garden, try to use a diverse assortment of forage plants. When possible, plant patches 1 meter square per plant variety. Plan ahead so that there are flowers blooming throughout the year.
Borage, Borago officinalis–Annual–Nectar
California, Poppy, Eschscholzia californica– Annual- Pollen
Ceanothus, Ceanothus cultivars– Perennial– Pollen
Clarkia, Clarkia unguiculata– Annual– Nectar
Tansy, Phacelia Phacelia tanacetifolia– Annual– Nectar/Pollen
Yarrow, Achillea millefolium– Perennial– Pollen
Coneflower, Echinacea purpurea– Perennial– Nectar/Pollen
Coreopsis, C. grandiflora cultivars– Perennial– Nectar/Pollen
Best cultivars are: ‘Flying Saucers’, ‘Sunny Day’, and ‘Tequila Sunrise’
Coreopsis, Coreopsis lanceolata– Perennial– Nectar/Pollen
Cosmos, C. bipinnatus, C. sulphureus– Annual– Nectar/Pollen
Gaillardia, Common cultivars– Perennial– Nectar/Pollen
Sunflower, Helianthus annuus– Annual– Nectar/Pollen
Make sure they are not low- or no-pollen cultivars
EDIBLES AND HERBS
Cucurbits: Zucchini, squash, cucumbers, melons– Annual– Nectar/Pollen
Lavender, Lavandula species– Perennial– Nectar
Mint, Mentha spicata– Perennial– Nectar
Oregano, Origanum species– Perennial– Nectar
Rosemary, Rosmarinus officinalis– Perennial– Nectar
Low-growing cultivars are best
Thyme, Thymus species– Perennia–l Nectar
This list was compiled from the Urban Bee Lab’s webpage, Best Bee Plants for California. You can find the entire list at helpabee.org.
Footnotes and other resources:
1. Klein AM, Vaissiere BE, Cane JH, Steffan-Dewenter I, Cunningham SA, et al. (2007) Importance of pollinators in changing landscapes for world crops. P R Soc B 274: 303–313.
2. Frankie G, Thorp RW, Hernandez J, Rizzardi M, Ertter B, Pawelek JC, Witt SL, Schindler M, Coville R, Wojcik VA (2009) Native bees are rich natural resource in urban California gardens. California Agriculture 63(3): 113-120.
3. Tomizawa M, Casida J (2003) Selective Toxicity of Neonicotinoids Attributable to Specificity of Insect and Mammalian Nicotinic Receptors. Annual Review of Entomology 48: 339-364.
4. Goulson D (2013) An overview of the environmental risks posed by neonicotinoid insecticides. Journal of Applied Ecology 50: 977-987
5. UCD website with lots of resources for making your own nests: https://beebiology.ucdavis.edu/NATIVEBEES/nativebeenestingsiteresources.html
Buchmann S, Nabhan GP (1996) The Forgotten Pollinators. Island Press, Washington, D.C. Print.
Grissel, E (2001) Insects & Gardens: In Pursuit of a Garden Ecology. Timber Press, Portland, OR. Print.