Planting a bee-friendly garden is easy!

I was just at our neighborhood block party and met many people I didn’t know- but they knew me because they’d seen me out in my front yard tending my tiny pollinator garden. They commented on how beautiful it is, and one even asked if I could help her with her landscaping. It’s amazing how creating habitat for bees also serves as a way to connect with my local community. 

Planting your own lovely pollinator garden is really satisfying and simple: A new study in the UK shows that planting your garden with pollinator-friendly flowering plants is easy and inexpensive. Plus some of the plants are common herbs that add to your culinary endeavors, including marjoram and lavender. Rosemary is another plant typical to urban landscaping that is highly attractive to bees. For the full story on BBC news, click here.

Last summer my husband and I planted native flowering plants along the “parking strip” in front of our house (the area between the side walk and the street). The area was just grass and weeds, which we pulled- then we turned the soil and amended it with gypsum (it has a lot of clay) and compost. To gather the plants, we went to the UC Botanic Garden sale, to the local California Native Plant Society Nursery, and to a neighborhood nursery, Westbrae. You can see the initial stages in the photo below. We enlisted a friend to help and got some nice pavers to make a walkway during a sale at a local hardware store.

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A little over a year later we have a colorful array of sages (salvias), buckwheat, native grasses including blue fescue, yarrow, and california lilac (ceanothus). We also added some succulents, which are classic xeroscape plants, and some non-natives from other Mediterranean regions including lavender and New Zealand flax. The city of Albany has a program where they cost-share the price of planting trees in parking strips, so we had them plant a red bud (though sadly they would only let us plant the eastern variety, not the native western species). I’m also considering getting 2 more plants to put in this winter: milkweed, which is loved by bees and butterflies alike, and phacelia, a california native plant with purple or while flowers that stick up like a scorpion tail and are bumble bees absolute favorite.

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If you want to encourage bee nesting, it’s important to leave bare soil. We decided not to mulch for weed suppression, though we do weed every 2 months or so. To fill in the spaces with bee-attractive blooms while leaving bare dirt, we collected a few poppy seeds from a nearby plant, and had dozens of poppies filling in the gaps this past spring and summer. We just bought a wildflower mix that we’ll sprinkle onto plot once the rains come- so next spring our front yard should be a pollinator paradise. 

When it’s really hot out we water about once a week- but most of the CA natives are drought tolerant and low maintenance. After they establish, we shouldn’t have to water too much at all. The best time of year to plant is now- so the rains provide the moisture the plants need to put down their roots and thrive come spring.

For more ideas on plants that attract pollinators check out the Xerces Society book Attracting Native Pollinators and the informative urban bee website helpabee. The UC Agricultural Experiment Station just published a guide on plant selection in California as well. With this wealth of resources, it will be easy to make your garden a pollinator refuge.

 

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To till or not to till . . .

The market near my home is sporting a massive pumpkin display in honor of the harvest season and the slew of upcoming holidays that incorporate gourds. The delicacies our festivities center around rely on native pollinators in order to swell to sometimes fantastic proportions. One species of native bee in particular, the squash bee (Peponapis purinosa), a specialist that only visits plants in the cucurbit family, including watermelon and pumpkin, is one of the critical players in our autumnal celebrations.

Squash bees, like 80% of all native bee species, builds it’s nests underground. It digs a tunnel with several lateral chambers off of it in which it lays it’s young. Most chambers are not too deep in the soil profile, ranging from 3 inches at the shallowest, to a few feet deep, with most around 5-10 inches. Squash bees prefer to nest near their source of pollen and nectar, which means that it nests within agricultural fields. Although the squash vines die out and get removed- the immature bees remain in their cells within the soil, waiting until next summer to emerge and find more squash blossoms. This means that any soil management can affect the young as they overwinter underground.

Katharina Ullman, a graduate student at UC Davis, has been looking at whether tilling negatively impacts squash bee pupating in agricultural fields. She experimentally added squash bees into flight cages and determined where they nested. She then disked and tilled up to 16 inches in the ground in half of these plots. The following summer (this year) she set up cages again to see whether the tilling affected the bees. She found that tilled plots had only half the number of emerging squash bees as untilled plots.

Most farmers disk every year, and till to the depth Katharina did every 3 years. This means they may be killing or disrupting up to half of the population of squash bees!  No till or low till methods may help to protect bee larvae and pupae that overwinter in underground cells- helping to bolster pollinator populations year to year, and helping to maintain delicious food on our holiday tables.

Picture of a Squash Bee in a Squash Bloom from Discover Life

(This research was presented at an awesome UC Cooperative Extension Seminar that Katharina and Rachael Long coordinated in Davis last Friday. I learned a lot about neat research projects going on in the region, that I hope to write about in the future- but this seemed most relevant to this time of year)

Are pesticides the problem?

Honey bees populations are hurting. This isn’t new news. Last winter saw a 42% increase over the previous year’s losses due to colony collapse disorder. Yet the bees don’t seem to be recovering despite significant efforts to understand the causes. The BBC published a wonderful graphic detailing the myriad factors that can influence colony heath, which range from climate, to farming practices, to disease, to pesticide use. So what’s the deal with pesticides, specifically, a class called neonicotinoids, which are getting a lot of press lately because of the recent moratorium in the EU? (I wrote about them in a past blog about Dave Goulson’s research in May)

There is a lot of skepticism as to whether neonics are the root cause of the honey bee problem. For example, the UK stated that they were unconvinced by the science to date. A recent piece focusing on a new paper by vanEngelsdorp makes it seem like all banning neonics would do is bring back the 25,000 bumble bees that were massacred in Oregon after an application to a flowering tree in a parking lot this past summer (bumble bees are threatened by a variety of diseases and are the key pollinators in most natural ecosystems, plus critical crop pollinators, so this loss is not minuscule nor unimportant).

In fact, neonics, a neurotoxin, and are more deadly to invertebrates than DDT. They can be lethal, but also have sub-lethal side effects that can alter a bee’s ability to forage or navigate normally. Studies have found them in food and honey residues and in the pollen bees take back to their young. The orchard mason bee matures less quickly when exposed to neonics, and bumble bees produce less offspring. The effects on ground-nesting bees are not well known, but the pesticides accumulate in soil, and can remain there for up to 6 years, so there is the potential that they could harm bees even in the absence of direct spraying. Neonics are often used as seed coats, and are absorbed into all parts of the plant tissue (known as a systemic pesticide), including the pollen and nectar.

To help answer some of the questions surrounding neonicotinoids, the Xerces Society for Invertebrate Conservation just released a report entitled, Are Neonics Killing Bees? They found that both native bees and honey bees are exposed to neonicotinoids in a varieties of ways, yet there are still gaps in the research that need to be addressed before we can form a clear picture of all the effects on bee health. They recommend suspending currently approved uses of neonics until their effects are better understood (in ecology this is known as the Precautionary Principle- acting with caution about a potentially detrimental product until we can be sure it is safe).  Similarly, they also suggest the EPA adopt a more cautious approach to approval of new pesticides- with more rigorous assessments of the risks to wild and managed bees. They also suggest better labeling that warns both agricultural users and homeowners about the extreme risks to pollinators, with reference to the contamination of nectar. And finally, they suggest legislators consider banning use of neonics for ornamental plants, where rates of application are much higher than on crops.

The Center for Food Safety has already sued the EPA to enhance labeling on products containing neonics that homeowners readily spray in their gardens without knowing the deleterious effects they can have on beneficial insects. There are numerous campaigns to increase awareness about the potential negative effects of pesticides. Avaaz has gathered over 1 million signatures. And while it may be true that colony collapse disorder may not disappear if we eliminate neonicotinoids, it might help other native bees, and reduce one of the threats to honey bees.

For more information about neonics, check out summaries provided by the Pesticide Action Network (more honey bee related) and the Xerces Society.

Hedgerows increase bee abundance within fields

There have been a number of studies that found hedgerows had higher numbers of bees and more diverse community composition than field margins without habitat enhancements, but a recent studies shows that this effect may extend into fields.

Farmers have expressed concern that if they place hedgerows along field borders, the hedgerows might actually compete with crops for pollination. Working in the same system that I work in around Davis, California, Dr. Lora Morandin and my PI Claire Kremen, tested whether hedgerows concentrated bees from the landscape, functioning as a sink, or created a source of bees, actually exporting them into surrounding fields.The evidence they collected suggests that bees were actually more abundant in fields that were next to hedgerows. Although most of the bees were concentrated along field edges (about 10 m into fields), the increase was noticeable up to 200 meters into fields. As for honey bees, they too were more common in hedgerows and adjacent fields- indicating that they too may be attracted to the floral resources restoration provides.

On a methodological note, the researchers found that specimens collected with pan traps (a standard passive bee collection method that involves setting out colored bowls filled with soapy water) were not different in any of the study types, however bees collected with nets that were actually foraging on plants were different. Morandin and Kremen found more bees pan traps placed in sites with fewer flowers, indicating bees might be more attracted to these traps when there are fewer available resources. They caution that pan traps may not be an accurate way of “assessing differences in pollinator communities among areas that differ in floral display.”

Overall, this study adds to the body of evidence showing that increasing vegetative diversity within agricultural landscapes increases bee diversity, which likely benefits crop pollination.

 

Morandin and Kremen. 2013. Hedgerow Restoration Promotes Pollinator Populations and Exports Native Bees to Adjacent Fields. Ecological Applications 23(4): 829-839