Posts Tagged: Robbin Thorp
That's because it's rarely seen.
Its narrow distribution range covers parts of southern Oregon (Jackson, Douglas and Josephine counties) and northern California (Siskiyou and Trinity counties). That's 190 miles north-south and 70 miles east-west.
"Franklin’s bumble bee has the smallest range of distribution of any of our 60 species of North American bumble bees, and perhaps of the 250 bumble bees in the world,” said noted bumble bee expert and native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis.
Thorp, who has been closely monitoring the Bombus franklini population since 1998, counted 100 that first year. In 2003, he found only three. And since 2006, only one.
Franklin's bumble bee may already be extinct, but he hopes not. Thorp and The Xerces Society for Invertebrate Conservation, headquartered in Portland, Ore., petitioned the U.S. Fish and Wildlife Service on June 23 to place it on the endangered species list.
A decision may be reached within 90 days.
“The decline of Franklin’s bumble bee is a signal that something is wrong in its environment,” said Thorp. “This is the canary-in-the-coal-mine measure.”
He hypothesizes that the key reason for its disappearance may be an exotic disease that spread from commercial bumble bee colonies to wild bumble bee populations.
“People often ask the value of Franklin’s bumble bee," said Thorp, a member of the California Academy of Sciences and The Xerces Society. "In terms of a direct contribution to the grand scale of human economies, perhaps not much, but no one has measured its contribution in those terms. However, in the grand scheme of our planet and its environmental values, I would say it is priceless.”“Loss of a species, especially a pollinator, diminishes our global environment. Bumble bees provide an important ecological service--pollination. This service is critical to reproduction of a huge diversity of plants that in turn provide shelter, food (seeds, fruits) to diverse wildlife. The potential cascade of effects from the removal of even one localized pollinator may affect us directly and indirectly.”
Is it too late to provide protection for a species that may already be extinct?
No, it's not.
“Other species, especially plants and insects, thought to be extinct have reappeared after years of not being seen,” the UC Davis scientist said. “When populations of species are in decline, they may reach such low levels that they are not detected for several years in a row, despite intensive surveys--flying under the radar so to speak. It is my hope that this is the case with Franklin’s bumble bee.”“One positive sign,” Thorp said, “comes from increasing finds the past two years of a related species, the Western bumble bee, which exhibited similar declines at the same time and places."
On his most recent trip, July 21-24, to the narrow distribution range, he didn't find Franklin's bumble bee but he did find the related Western bumble bee at two sites, one individual at each site.
That's a good sign. Perhaps B. franklini will eventually show up as well. Thorp is planning another trip in mid-August and another in early September.
Meanwhile, if the critically imperiled Franklin's bumble is granted protective status, a snowball effect could occur.
This could “stimulate research into the probable causes of its decline,” Thorp said. “This may not only lead to its recovery, but also help us better understand environmental threats to pollinators and how to prevent them in future. This petition also serves as a wake-up call to the importance of pollinators and the need to provide protections from the various threats to the health of their populations.”
More about the mission to Save Franklin's bumble bee
Watch Robbin Thorp's webcast about Franklin's bumble bee
Franklin's bumble bee
They're populating the sandy cliffs of Bodega Head, Sonoma County. A sure sign of their presence: dense clusters of turrets.
When they're not foraging among the wild radish (genus Raphanus), lupine (genus Lupinus) and other plants, these ground-dwelling bees are digging nests and rearing their young.
"The female sucks up fresh water from nearby, stores it in her crop--like honey bees store nectar--for transport to the nest," said native pollinator specialist Robbin Thorp, emeritus professor of entomology at the University of California, Davis.
"She regurgitates it on the sandstone, and excavates the moistened soil," he said. "She carries out the mud and makes the entrance turret with it."
The digger bees are sometimes referred to as "alternative pollinators," but they're all members of the Apidae family, which includes honey bees (the super pollinators), bumble bees, carpenter bees, sunflower bees, orchid bees, cuckoo bees and the like.
Building a Nest
If you like to take photos of insects that are as small as a grain of rice, then you'll love--absolutely love--stalking a sweat bee.
Sweat bees, members of the worldwide family Halictinae and order Hymenoptera, are so-named because they are attracted to human perspiration or "sweat." They probably lap up perspiration because of the salt content, according to Christopher O'Toole and Anthony Raw, authors of Bees of the World.
The most important of the many genera, the authors say, are Halictus and Lasioglossum, which are common to both the Old World and New World.
Speaking of common, Halictus is also common in bee friendly gardens and swimming pools. Ever gone for a swim and feel a tiny insect sting you? It may have been a sweat bee. ("Their sting is only rated a 1.0 on the Schmidt Sting Pain Index, making it almost painless," according to Wikipedia.)
O'Toole and Raw point out that some sweat bees are only 4mm long, which is why they can be easily overlooked and so difficult to identify.
What's unique are about these ground-nesting bees? The females of all species of sweat bees mate before winter. "This means that, unlike female solitary bees of other families, those of halictids do not have to mate before founding a nest in the spring," they write.
Native pollinator specialist Robbin Thorp, emeritus professor of entomology at the University of California, Davis, identified this little pollen-packing sweat bee (below) as a female sweat bee, Halictus tripartitus.
She was nectaring a tower of jewels (Echium wildprettii) in our yard and packing a heavy load of blue pollen she'd gathered from the plant.
The tower of jewels is native to the Canary Islands. So, if you visit the Canary Islands, you can probably see--and photograph--this little sweat bee there, too.
Ever heard of a polyester bee?
We encountered a plasterer or "polyester" bee on a recent trip to Bodega Bay.
A female Colletes fulgidus longiplumosus, as identified by native pollinator specialist Robbin Thorp, emeritus professor of entomology at the University of California, Davis, was foraging on a seaside daisy (Erigeron) along a sandy cliff off Bodega Head, Sonoma County.
She was covered in pollen.
The common name, polyester bee (family Colletidae), refers to the cellophane-like polyester material females secrete to line their burrows, Thorp said. These bees, he noted, nest in the same cliff faces with Anthophora bomboides stanfordiana (a faux bumble bee), but do not have turrets. A polyester membrane “doggy door" guards the nest entrances.
Worldwide, there are more than 20,000 identified species of bees.
The polyester bee is one of them.
It's good to see so much interest in bees.
When folks think of bees, they usually think "honey bees." However, our European or western honey bee (Apis mellifera) is one of a total of seven species of honey bees found throughout the world.
Worldwide, there are some 20,000 described species of bees.
University of California scientists Robbin Thorp, Gordon Frankie and Ellen Zagory will be discussing a few of them in their "Buzz About Bees" program on Saturday, June 5 at the Bouverie Preserve in Glen Ellen, Calif.
Thorp is a native pollinator specialist and emeritus professor of entomology at UC Davis who continues to do research. Frankie is a professor and research entomologist at the UC Berkeley Division of Insect Biology. Zagory is director of horticulture, UC Davis Arboretum.
The registration deadline for this session, a science discussion about the "plight of Sonoma County's pollnators," closed May 28 but Thorp and Frankie continue to call attention to the plight of the pollinators. They talk about bumble bees, cuckoo bees, blue orchard bees, sweat bees and the like. Some bees are defined by what they do: leafcutters, masons and miners.
And Zagory is an expert on plants, especially ornamental plants. One has only to walk through the UC Davis Arboretum--or ask her to identify a plant--to confirm that!
We hope the "buzz about bees" continues to draw widespread interest.
Honey Bee on Lavender
Yellow-Faced Bumble Bee