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Pollinators in trouble

A honeybee searches for nectar on ceanothus.
On April 30, Barbara Allen-Diaz, vice president of the UC Division of Agriculture and Natural Resources, will wear bees – live honeybees. The event is a fundraiser for undergraduate education, and Allen-Diaz, who has endured bee stings in the past, is willing to take the risk for this important cause. She'll have the help of a noted bee wrangler, UC Davis emeritus professor of entomology Norm Gary. Gary has performed such unlikely stunts as playing the clarinet while covered with honeybees. He will apply a synthetic pheromone to Allen-Diaz's hands to attract the bees, which he says are unlikely to sting unless provoked.

“I'll be holding a precious resource in my hands, one that is essential to life on earth,” says Allen-Diaz. “I'll be placing my hands in Norm's hands to raise awareness about the value of honeybees.”

While raising money for education is certainly a worthy goal, as Allen-Diaz says, the event also draws attention to the plight of our most important agricultural pollinator. In 2006, a number of beekeepers in the Western U.S. noticed their hives had lost 30 to 70 percent of their worker bees. The phenomenon, now known as colony collapse disorder (CCD), is still not fully understood, though a number of factors are believed to be involved. They include habitat loss or degradation and fragmentation, poor nutrition, certain bee management and agricultural practices, natural and chemical toxins, diseases, and parasites. Any one of these factors can affect the insects' ability to combat any of the others. Isolating a single cause, if there is one, has proved elusive.

Many of the fruits and vegetables on the tables of the world are pollinated by insects, particularly bees, and if they were to disappear, our sources of plant food would be restricted to grains and not too much else. It's no wonder CCD is such a concern (for example, see the United Nations Environmental Program 2010 report on Global Bee Colony Disorder  and USDA, Honey Bees and Colony Collapse Disorder.

Yellow face bumblebee.
It's not just honeybees, either. Pollinators in general are on the decline worldwide, probably for many of the same reasons that are listed as factors in CCD. They have an essential ecological function on every continent except Antarctica, not merely in service to agriculture. Losey and Vaughn (2006) estimate the value to the U.S. economy of native insects (not honeybees, which are native to Europe) to be at least $57 billion.

As human population grows and becomes more urban, and as habitats get more fragmented, it is no longer adequate to focus conservation efforts merely in non-urban, non-working landscapes.

“We need to figure out how to accommodate as many native species as possible in these kinds of places,” says Patrick Huber of the City of Davis Open Space and Habitat Commission, which has adopted pollinator habitat enhancement as a working goal. The Commission is working to compile a GIS dataset of known big patches of habitat in Davis, in order map pollinator resources around town.

Huber is a geographer in the Landscape Analysis and Systems Research lab at UC Davis, where he focuses on spatial scale in conservation planning. He is working on a tool to help match gardeners with plants that will grow well in their regions, that are locally available, and that provide a network of resources for pollinators throughout the urban landscape and on into the agricultural landscape. For the moment this project is being piloted in Davis, but the hope is to expand it to other communities, tying in resources such as CalFlora.

A recent workshop at UC Davis sponsored by the California Center for Urban Horticulture, Your Sustainable Backyard: Pollinator Gardening, focused on this very issue: what gardeners can do to help pollinators, many of which are bees. (Of 19,500 known bee species in the world, 4,000 can be found in North America and 1,600 in California. There are at least 300 species of bee in Yolo County alone.) Urban gardeners can help pollinators by:

  • Planning for succession blooming (in the Central Valley, that means late winter through fall)
  •  Putting plants in clumps at least 4 feet long if possible (honeybees, especially, like to specialize)
  •  Putting in plants that provide both nectar and pollen (nectar is fuel for adult bees, pollen is protein for the young)
  • Using native plants where possible; they're drought tolerant and have what our native bees need
  • Avoiding most-toxic pesticides and herbicides
  • Providing a clean source of water (a slow-dripping tap on a sloped surface is ideal; bees like to drink from very shallow sources)
  • Providing cavity nest holes in wood for carpenter and other bees
  • Leaving some areas of gardens unmulched for ground-nesting bees

There are ways the agricultural landscape can be made more hospitable, too. Neal Williams, professor of entomology at UC Davis, has been working on a project to install 600- to 800-meter plots of flowering plants alongside large fields as resources for pollinators. This has moved out of the trial phase into test plots in coastal and foothill areas as well as in the Central Valley.

Meanwhile, we can all help count our pollinators on May 8, the Day of Science and Service to celebrate 100 years of Cooperative Extension in California. We'll be conducting our own pollinator count here outside the ANR building in Davis: join us, or let us know about yours!

Many thanks to Kathy Keatley Garvey for use of her photos.

 

Posted on Wednesday, March 26, 2014 at 9:05 AM
  • Author: Alison L Kent

Watching out for native worker bees

With warm weather and mostly dry skies, some California farmers are prepping their fields for spring planting. On many fields used to grow squash and pumpkins, native squash bees (Peponapis pruinosa), valuable pollinators for squash growers, are nesting in the soil, waiting for spring emergence.  With over ten thousand acres of squash and pumpkins grown in California in 2011, the success of pollination covers a lot of ground.

Female male and female squash bee on male flower, courtesy Katherine Ellis
New studies are showing that native bees may be more productive pollinators than honey bees, and that in some cases, the presence of native bees can boost the pollinating potential of commercially produced honey bees. But native bee populations face threats that are not yet fully understood. 

For native bee researcher Katharina Ullmann, understanding how these bees will be impacted by the upcoming tillage and other farming practices are big questions that can help farmers make decisions that protect native bee populations in their fields and maximize the benefit farmers see from pollinators. Ullmann was recently awarded a grant from Western SARE (Sustainable Agriculture Research and Education) and the National Science Foundation to fund her doctoral research on how crop rotations and tillage practices affect native squash bee populations.  

Female squash bee on female flower, courtesy Katherine Ellis
Her work is part of the Bee Biology lab run by Neal Williams, assistant professor of Entomology at UC Davis and a contributing author to recent studies on the benefits of native bees. Too, Ullmann serves on the Advisory Board to the Agricultural Sustainability Institute at UC Davis, linking field-level entomology to broader sustainability research.     

Native squash bees nest 5 to 20 inches deep in the soil, and plowing or disking often disturbs soil as much as 20 inches deep, potentially damaging bee nests. Conservation tillage and no-till practices are increasingly seen as ways to lower fuel use and on-farm emissions from nitrogen and carbon dioxide, as well as decrease water runoff. Protecting native bee populations could potentially be an additional co-benefit to these methods.

I think about native bees as an insurance policy and potentially a yield increaser,” says Ullmann. “Honey bees are important; they’re always going to be important.  But it can be beneficial for growers to know if they have crop-pollinating native bees flying around if, for example, honey bee prices spike or if it’s hard for a grower to get the number of honey bee colonies he or she needs.”  Too, with new studies highlighting the productivity of native bees (in some cases doubling fruit set compared to honey bees), there is growing incentive to protect nesting grounds.

The results of Ullmann’s tillage study, in coordination with a parallel study on the effect of crop rotation on bee populations, will be turned into a user-friendly web tool for farmers to assess which combination of in-field practices will likely be best for fostering bee populations. “In creating these models of tillage and crop rotation practices, we’re hoping to help farmers find the synergy between different farming practices that yield the greatest benefits,” says Ullmann. 

“Not all farmers will change tillage or crop rotation practices just because of bees, but maybe this is another piece of information that farmers can use to make informed management decisions. “Ultimately,” says Ullmann, “my goal is to provide farmers with that opportunity.”

Looking for squash bees on your farm or in your garden? They look similar to honey bees but with fuzzier legs that lift dry pollen from squash blossoms, and male bees have a yellow spot on their face that resembles a nose. But perhaps the easiest way to identify them — gently squeeze a closed squash blossom and wait to hear a buzz. The bee inside is likely a native squash bee, resting up in preparation for more work.

Posted on Thursday, April 4, 2013 at 8:47 AM
Tags: bees (7), pollinators (5), tillage (1)

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