Volunteers to count bees on sunflowers in study

SF Gate
Ron Sullivan, Joe Eaton
Wednesday, April 2, 2008

Here’s another opportunity to do your bit for science without leaving your yard.

San Francisco State University biologist Gretchen LeBuhn wants you to grow a sunflower – not just any old sunflower, but the North American native species Helianthus annuus – and monitor the bee traffic once it blooms. It’s called the Great Sunflower Project, and with it LeBuhn hopes to connect the ecosystem services of bees with issues of food security.

LeBuhn started out as a botanist but became fascinated with bees. When teaching a bee-identification course at the Southwest Research Center in Arizona, she realized how little most people know about this diverse (1,500 species exist in California, 500 in the Bay Area) and ecologically vital group.

Honeybees are declining

“There’s very good data that honeybees seem to be declining, and spotty data that native bees aren’t doing well,” she said. Several researchers, including Gordon Frankie at UC Berkeley, have been studying urban bee communities. But no one had attempted a continentwide survey of the state of the bees.

LeBuhn, who provides the seeds, wants Great Sunflower Project participants to use a specific kind of sunflower so their observations can be standardized. H. annuus is “a classic bee plant.” Its long blooming season – potentially May to September – should attract a broad range of native bees that fly at different times of the year.

“Sunflowers are easy to grow, easy to watch bees on, and bees love them,” she added. Schools, including San Francisco’s Willie Brown Academy, and community gardens will have their own patches.

Bee watchers will be asked to spend half an hour – early in the day, before the pollen is depleted – on two Saturdays each month taking note of what kinds of bees visit their sunflowers and how long it takes for the first five to arrive. The identification part has been field-tested.

“We’re comfortable that people can identify bumblebees,” LeBuhn said, “and honeybees possibly.” Other possibilities are large, solitary, shiny black carpenter bees and green “metallic” bees. Reporting “just bees” is fine, though. The time the bees spend at the sunflowers indicates how much pollination service the flower is getting.

That’s where the food-security connection comes in.

“Worldwide, community gardens provide up to 15 to 20 percent of food,” explains LeBuhn. “For the urban poor in some countries, 60 to 80 percent of their food is what they raise. It’s often the only material contribution women can make to the household economy. I’m interested in whether community gardens are getting enough pollinator services in urban settings.”

Although it may not be the norm in the Bay Area, she said, community gardens in other countries can have high pesticide use – and beneficial insects like bees are not immune to pesticides. If funding is available, she’d like to take the Great Sunflower Project international.

Population problems
Honeybees beset by the mysterious colony collapse disorder have been in the headlines, but LeBuhn notes that some of North America’s bumblebees are also in trouble. UC Davis Professor Emeritus Robbin Thorp said at least one species, the Franklin’s bumblebee (Bombus franklini) of Northern California and southern Oregon, may already be extinct.

Thorp spends his summers searching for B. franklini in its narrow zone of distribution between the Coast Range and the Cascades-Sierra. Last year, he found none; in 2006, a single worker at Mount Ashland in Oregon. Franklin’s bumblebee is a generalist, gathering pollen from lupines and poppies and nectaring at mints. The plants are still there, but the bee has gone missing before it could be listed as endangered.

“The western bumblebee, a close relative of Franklin’s, was once common from Monterey County to southern British Columbia,” Thorp said. “They are virtually undetectable in those areas now.” Some eastern bumblebees are also declining.

Victims of success?
North American bumblebees may be victims of their success as pollinators; for certain crops, they’re better than honeybees. The bumblebee’s secret is the ability to vibrate its body by using its wing muscles, causing pollen release through pores in a flower’s stamens.

“Buzz pollination” is crucial for hothouse tomatoes and peppers. Cranberries, strawberries and blueberries are also bumblebee-pollinated – all told, said Thorp, 15 percent of our food crops, valued at $3 billion.

Unlike honeybees’ hives, bumblebee colonies die off annually, leaving newly mated queens to overwinter and start the cycle again in spring. The bumblebee trade has gone global, with North American queens shipped to Europe to rear colonies. “When the colonies were shipped back to us, I suspect they may have picked up diseases from European bumblebees,” Thorp said. The main suspect is the microorganism nosema, present in commercial Western bumblebee stocks since 1998.

It’s sobering to realize just how dependent we all are on pollinating insects, native and otherwise. LeBuhn’s Great Sunflower Project might start to fill large gaps in our knowledge of what Edward O. Wilson calls “the little things that run the world.”

Resources:
— The Great Sunflower Project: www.greatsunflower.org. Includes a bee identification guide, to be published soon in book form.

— Urban Bee Gardens:  HYPERLINK “http://nature.berkeley.edu/urbanbeegardens” nature.berkeley.edu/urbanbeegardens. Gordon Frankie’s site.

— Xerces Society Red List of Pollinator Insects: links.sfgate.com/ZCWD. The Xerces Society supports conservation of insects and other invertebrates. Its Red List identifies pollinators at risk.
— “The Forgotten Pollinators” by Stephen L. Buchmann and Gary Paul Nabhan (Island Press; 1996; $30, paperback).

Joe Eaton and Ron Sullivan are freelance nature and garden writers in Berkeley. E-mail them at home@sfchronicle.com.


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