We remember seeing a varroa mite attached to a foraging honey bee one warm summer day in our pollinator garden. The mite was feeding off the bee and the bee was feeding on the nectar of a lavender blossom.
Didn't seem fair.
We've never seen a varroa mite on bumble bees or carpenter bees, but Davis photographer Allan Jones has--and he's photographed them. (See below)
When varroa mites tumble off a honey bee and into a blossom, they can hitch a ride on other insects, such as bumble bees and carpenter bees.
"Varroa have been recorded hitching rides on bumble bees and yellowjackets," observed native pollinator specialist Robbin Thorp, distinguished emeritus professor of entomology at UC Davis. "Varroa have been reported as feeding on larvae of these and other critters--but not successfully reproducing on them. Also bumble bees and yellowjackets typically overwinter as hibernating queens not as perennial colonies like honey bees. Thus they are not suitable hosts for Varroa."
Extension apiculturist emeritus Eric Mussen says that bees other than honey bees aren't reproductive hosts for the varroa mite.
"As far as I know, Varroa destructor may be able to find soft areas of the exoskeleton of insects other than honey bees and feed on them," he says. "I have no idea whether or not the substitute hemolymph would sustain the mites for very long. The mites have practically no digestive capabilities. They simply utilize the previously-synthesized bee blood, to which they seem to be perfectly adapted."
"Since the mites reproduce on honey bee pupae, there are a number of considerations about potential other reproductive hosts," Mussen said, citing:
- Are the nutrients of the substitute host close enough to those of honey bees to support immature mite development?
- Can immature mites that develop properly at honey bee cell environmental conditions (temperature and relative humidity) find a similar environment in the nests of other insects?
- Do other insects tolerate the presence of mites on their bodies or in their brood nests?
Like honey bees, bumble bees do segregate their pupae in single cells, Mussen says, but he was unable to find any studies devoted to whether bumble bee pupal conditions support Varroa destructor reproduction.
Sounds like a good research project!
Feb. 14 was a perfect day for foragers, as the temperature climbed into the '70s, an unusually warm February day.
The site: The Glen Cove Marina in Vallejo, Calif., across the Carquinez Straits from Crockett.
We focused on one Bombus vosnesenskii--but only because the other four buzzed out of camera range. For 10 minutes, we watched her work the rosemary, buzzing from flower to flower as honey bees and syrphid flies zeroed in for their share, too.
But look at the bumble bee's pollen load, reminiscent of Halloween candy corn, those triangle-shaped yellow, orange and white-layered sweets.
"She obviously switched from one plant species with pale pollen to one with orangish pollen and maybe back again during her foraging bout," noted native polinator specialist Robbin Thorp, distinguished emeritus professor of entomology at UC Davis and co-author of California Bees and Blooms: A Guide for Gardeners and Naturalists (Heydey) and Bumble Bees of North America: An Identification Guide (Princeton University Press.)
"A fickle forager," Thorp declared. "Rosemary has whitish pollen, but it is usually a nectar resource for honey bees and others. So there must be some other plants being visited by B. vos. females in the area."
Indeed there were. California golden poppy (the state flower), wild radish, oxalis, and mustard.
"Detective" Thorp quickly figured it out. "The wild radish, mustard, and oxalis all have yellow pollen. Poppy has orange pollen. So it looks like your female may have started on rosemary (upper whitish part of the load), moved over to poppy for a while, and back to rosemary (bottom pale part of the load). Since poppy produces no nectar, visits to rosemary are primarily to tank up on nectar for flight fuel and apparently to collect some pollen there as well. It is often said that a mix of different pollen types is best for bees, so she is picking up a balanced diet for her babies."
Bottom line: When you capture an image of a bumble bee, you may not know where it's going, but a top-notch pollinator specialist can tell you where it's been!
Talk about a pollen-packing bumble bee.
A yellow-faced bumble bee, Bombus vosnesenskii, displayed quite a heavy load of orange pollen recently as it foraged on hairy vetch in the Hastings Preserve, Carmel, owned and operated by the University of California, Berkeley.
Did you know that Monday, June 15 marks the start of National Pollinator Week?
It's sponsored by the Pollinator Partnership, which offers these fast facts about pollinators:
- About 75 percent of all flowering plant species need the help of animals to move their heavy pollen grains from plant to plant for fertilization.
- About 1,000 of all pollinators are vertebrates such as birds, bats, and small mammals.
- Most pollinators (about 200,000 species) are beneficial insects such as flies, beetles, wasps, ants, butterflies, moths, and bees.
- In the United States, pollination produces nearly $20 billion worth of products annually
In observation of National Pollinator Week, the UC Davis Department of Entomology and Nematology is planning an open house at its bee garden, the Häagen-Dazs Honey Bee Haven, from 5:30 to 7 p.m., Friday, June 19. The half-acre bee garden is located on Bee Biology Road, next to the Harry H. Laidlaw Jr. Honey Bee Research Facility, west of the central campus.
Activities will include bee observation and identification, honey tasting, sales of native bee houses to support the haven, and information about low-water plants.
You're likely to see such pollinators as honey bees, bumble bees, sweat bees, syrphid flies, and butterflies.
The open house is free and open to the public. The garden, planted in the fall of 2009 during the tenure of Lynn Kimsey, then interim chair of the UC Davis Department of Entomology and Nematology, is now managed by Christine Casey, staff, and Extension apiculturist Elina Niño, faculty.
It showcases the work of the UC Davis Art/Science Fusion Program, co-directed and co-founded by Diane Ullman and Donna Billick; and the work of students in Entomology 1, taught by Ullman and Billick. The state-of-the-art fence that circles the garden is the work of Eagle Scout Derek Tully of Boy Scout Troop 111, Davis.
The bee garden is open daily from dawn to dusk.
The European honey bee, also known as the Western honey bee, has been in the United States for s-o-o-o long that we think it's a native.
It's not. European colonists brought the honey bee (Apis mellifera) to the Jamestown colony (Virginia) in 1622. The native Americans called it "the white man's fly." And the honey bee wasn't even introduced to California until 1853. That was in the middle of the California Gold Rush, 1848-1858, when it arrived in the San Jose area.
Our ancestors quickly became quite fond of the industrious little pollinator and honey/wax producer buzzing around them.
Today, as they did, we frequently see non-native and native bees sharing nectar resources, such as in the photos below of honey bees and yellow-faced bumble bees (Bombus vosnesenskii).
We're often asked: "Do honey bees, being an invasive species, impact the native bees?"
We put that question to Extension apiculturist Eric Mussen of the UC Davis Department of Entomology and Nematology. He's served as California's Extension apiculturist since 1976, almost 40 years.
His answer: "We do not have a definitive answer to that question. But, since honey bees have been living in what is now the U.S. for just short of 400 years, it is likely that honey bees and native bees determined, long ago, how to partition resources at any particular location so that both species survived. It is true that only honey bees can be moved into and out of a specific location overnight, and that might put a stress on local populations of native bees, but I never have heard of honey bees eliminating native bees from any particular spot."
That's the buzz on bees.
Or to put it more precisely, three Bombus melanopygus queens.
Early this morning, in between dark and dawn, three black-tailed bumble bees buzzed around our porch lights. Now, bumble bees don't venture out at night and they certainly don't head for porch lights--they head for flowers in the daytime--so immediately we're hypothesizing an infestation by the parasitoid phorid fly, Apocephalus borealis, aka "zombie fly."
We had earlier heard Professor John Hafernik of San Francisco State University discuss this fly at an entomological meeting in Sacramento.
The female flies lay their eggs in bumble bees, wasps and honey bees. Certainly not a nice thing to do. Eventually the eggs hatch into larvae and emerge from the dead host.
It was Hafernik who discovered that the "zombie fly" infests honey bees. He and his colleagues published their work, "A New Threat to Honey Bees, the Parasitic Phorid Fly, Apocephalus borealis," in PLOS One in January 2012. They revealed that the parasitized, disoriented honey bees leave their hives at night and head for the lights.
"After being parasitized by the fly, the bees abandon their hives in what is literally a flight of the living dead to congregate near lights," said Andrew Core of the Hafernik lab. 'When we observed the bees for some time—the ones that were alive—we found that they walked around in circles, often with no sense of direction."
Zombies. Or "ZomBees."
Hafernik and crew sounded the alert. They launched a citizen science project called ZomBee Watch, sponsored by the San Francisco State University Department of Biology, the San Francisco State University Center for Computing for Life Sciences and the Natural History Museum of Los Angeles County.
Fast forward to today...and the three bumble bees buzzing around our porch lights. That erratic, uncharacteristic, porch-light behavior prompted us to take them to native pollinator specialist/bumble bee expert Robbin Thorp, emeritus professor of entomology at UC Davis. Thorp is a co-author of the pending Bumble Bees of North America: An identification Guide (Princeton University Press).
It was he who identified them as Bombus melanopygus queens.
Thorp placed them in his "comfy" bumble bee-rearing chamber/observation box in the Harry H. Laidlaw Jr. Honey Bee Research Facility, provided nourishment (which the ladies accepted gracefully) and now it's wait-and-see.
Phorid flies? Nematodes? Something else? Nothing?
Don't know. However, as of 5 p.m. today, all three are alive.
"Just checked your three fuzzy ladies," Thorp reported. "They are still active and doing well."
In addition to carbohydrates, Thorp gave them a protein patty made by staff research associate/beekeeper Billy Synk, manager of the Laidlaw facility.
"I'll put in a pollen lump or two tomorrow," Thorp said, "to see if any are interested in becoming broody and starting a nest."/span>