Posts Tagged: pollen
Why is that in a honey bee colony, workers can carry pollen but not the queen?
Well, scientists from Michigan State University and Wayne State University have discovered the answer.
They've isolated the gene that's responsible for leg and wing development, according to a news brief in Entomology Today, published by the Entomological Society of America (ESA). The 7000-member ESA, by the way, is headed by president Frank Zalom, integrated pest management specialist and professor of entomology at UC Davis.
The scientists' bee research is published in the current edition of Biology Letters.
“This gene is critical in making the hind legs of workers distinct so they have the physical features necessary to carry pollen,” said MSU entomologist Zachary Huang. “Other studies have shed some light on this gene's role in this realm, but our team examined in great detail how the modifications take place.”
"The gene in question is Ultrabithorax, or Ubx. Specifically, the gene allows workers to develop a smooth spot on their hind legs that hosts their pollen baskets. On another part of their legs, the gene promotes the formation of 11 neatly spaced bristles, a section known as the 'pollen comb.' The gene also promotes the development of a pollen press, a protrusion also found on hind legs, that helps pack and transport pollen back to the hive."
What the research team did was to isolate and silence Ubx, the target gene. "This made the pollen baskets, specialized leg features used to collect and transport pollen, completely disappear," Entomology Today reported. "It also inhibited the growth of pollen combs and reduced the size of pollen presses."
The scientists acknowledge that this won't provide a solution to Colony Collapse Disorder (CCD). They think, however, that their research could lead to bees becoming better pollinators; they could carry larger pollen loads.
Speaking of loads, have you ever seen a bee so heavy with pollen that you wonder if she can lift off? It seems somewhat like a human being weighted down with a bowling ball.
The next time you observe a bee foraging, check out the pollen load. If you're lucky, you'll see the bee packing the pollen, adjusting the load before she buzzes off back to her colony.
Honey bee packing pollen on an almond tree at UC Davis--on the grounds of the Harry H. Laidlaw Jr. Honey Bee Research Facility-- several years ago. (Photo by Kathy Keatley Garvey)
Now that's a load of pollen! Honey bee inside a pomegranate blossom. (Photo by Kathy Keatley Garvey)
The California Gold Rush (1848-1855) has nothing on honey bees.
Sometimes foraging honey bees are covered with their own kind of gold--pollen--or protein for their colonies.
We saw this honey bee dusted with gold from head to thorax to abdomen as she gathered pollen from blanket flowers (Gaillardia). Her flight plan seemed uncertain, as her load was heavy and her visibility, poor. She struggled to take off, but take off she did.
Speaking of the Gold Rush and honey bees, entomologists always associate the arrival of honey bees in California with the California Gold Rush. That's because honey bees were introduced to California in 1853, right in the middle of the Gold Rush.
Back then, the hills were covered with wildflowers where bees gathered nectar (carbohydrates) and pollen (protein). Today, however, scientists are worried about bee malnutrition.
"Honey bee colonies need a mix of pollens every day to meet their nutritional needs," says Extension apiculturist Eric Mussen of the UC Davis Department of Entomology and Nematology. "In fact, they should have a one-acre equivalent of blossoms available to them daily to meet their demands. They can fly up to four miles from the hive--a 50-square mile area--to gather that food and water (and propolis, plant resin)."
A worried beekeeper recently asked him about the declining bee population and wondered why his own colonies were dwindling. In addition to malnutrition, Mussen listed a few other possibilities:
Varroa mites – "They suck the blood from developing pupae and adult bees, shortening their lifespans. They vector virus diseases, the easiest to see being deformed wing virus. If you have adult bees around the colony with curly, undeveloped wings, then you have too many mites. If you see mites on the bees when you look in the hive, that is too many mites."
Nosema ceranae and other diseases – "You need a microscope to see the spores of a Nosema infection. Go to Randy Oliver’s webpage, Scientificbeekeeping.com, and look at the information on Nosema ceranae and spore counting."
Contact with toxic chemicals – "Since your bees can fly up to four miles away to forage, that also is the distance within which they can get into trouble with bee-toxic chemicals. It is not likely that the organic farm is a source. However, if there are other farms around, or if your neighbors (golf courses, shopping centers, parks, playgrounds, etc.) are having problems with sucking or chewing insects, they may have used one of the neonicotinoids on their shrubs or trees. Turf and ornamental dosages are considerably higher than those used in commercial agriculture. So, the amounts of toxins in nectar and pollens can be toxic to honey bees and other pollinators."
Mussen also acknowledged that California buckeye blossoms are toxic to bees. "This was a fairly dry spring," he said. "Not too many weeds and wildflowers were around when the California buckeye came into bloom. Buckeye pollen is toxic to developing bee brood and to adult bees, if it gets to be their primary food source in the colony."
The problem could also be due to other issues as well, Mussen said. "Maybe the queens did not mate with enough drones, or the queens got too hot or too cold during their journeys to your hives, etc."
"As beekeepers, it is up to you to stick your nose in the hive, look at everything and try to determine what may be going wrong. If you are feeling way too new at this to have any idea of what is going on, then contact your local bee club--there is one in practically half of the California counties--and find someone to help access your problems."
And the pollen, that precious protein? "When beekeepers examine their hives, they should see a good supply of pollen with many colors," Mussen says.
Honey bee is covered with pollen from a blanket flower, Gaillardia. (Photo by Kathy Keatley Garvey)
Honey bee is dusted with pollen from the blanket flower. (Photo by Kathy Keatley Garvey)
Lift off? The bee struggles to take off. (Photo by Kathy Keatley Garvey)
It's the Fourth of July--a time to celebrate our nation's Independence Day.
Hurrah for the red, white and blue!
That also covers red, white and blue pollen collected by our honey bees.
If you look closely, you'll see their "patriotic" colors.
"The importance of pollen to the health and vigor of the honey bee colony cannot be overstated," writes emeritus entomology professor Norman Gary of the University of California, Davis, in his best-selling book, "Honey Bee Hobbyist, The Care and Keeping of Bees."
"Honey satisfies the bees' carbohydrate requirements, while all of the other nutrients---minerals, proteins, vitamins and fatty substances--are derived from pollen. Nurse bees consume large amounts of pollen, converting it into nutritious secretions that are fed to developing larvae. During an entire year, a typical bee colony gathers and consumes about 77 pounds of pollen."
Gary adds: "Pollen in the plant world is the equivalent of sperm in the animal world. Fertilization and growth of seeds depends upon the transfer of pollen from the male flower parts (anthers) to the receptive female parts (stigmas)."
Our honey bees are not native to America, but they've been here so long that many people think they are. European colonists brought them here to Jamestown Colony, Virginia, in 1622. Honey bees were established here before our forefathers signed the Declaration of Independence on July 4, 1776.
So, today, a time to celebrate the Fourth and a time to celebrate our honey bees, Apis mellifera.
Honey bee packing red pollen from a rock purslane. (Photo by Kathy Keatley Garvey)
Close-up of white pollen. (Photo by Kathy Keatley Garvey)
Blue pollen from a bird's eye blossom. (Photo by Kathy Keatley Garvey)
Bees carry pollen in their pollen baskets, but that's not the only place.
"Pollen grains adhere to the bee's hairs, influenced by opposite electrical charges," writes Norman Gary, emeritus professor of entomology at the University of California, Davis, in his popular book, Honey Bee Hobbyist: The Care and Keeping of Bees.
Bees comb and brush the pollen into their pollen baskets but, as Gary writes, "Fortunately for the plants, bees aren't 100 percent efficient at transferring the pollen to the pollen baskets. Thousands of pollen grains may still remain on their bodies even after they finish grooming. Bees leave enough pollen behind, depositing it accidentally on female flower structures to ensure effective pollination."
Honey bees collect nectar, pollen, propolis (plant resin) and water to keep the colony humming. Nectar is the colony's carbohydrate (sugar) while pollen is the protein. Pollen also contains such nutrients as minerals, vitamins and fatty substances.
"During an entire year, a typical bee colony gathers and consumes about 77 pounds of pollen," Gary writes, adding that a single pollen-foraging bee will average 10 trips per day. "When pollen is abundant, a bee can gather a full load in as little as ten minutes by visiting several dozen flowers," he points out.
If you look closely, sometimes you'll see a bee covered with pollen. The bee below was on a yellow coneflower (Echinacea paradoxa) in Napa.
If you're allergic to pollen, these photos just might make you sneeze!
Honey bee covered with pollen; she is on a yellow coneflower, Echinacea paradoxa. (Photo by Kathy Keatley Garvey)
Close-up of honey bee covered with pollen. (Photo by Kathy Keatley Garvey)
Ever watched an in-flight honey bee packing her load of pollen?
A foraging bee carries her ball-like load of pollen on her hind legs and continually moistens it with a little nectar. The size and shape changes as she works. Sometimes you'll see BB-sized loads and at other times the pellets seem as large as beach balls. The color varies, depending on the color of the pollen she collects.
In the UC Agricultural and Natural Resources (UC ANR) publication, Beekeeping in California, (now out of print, but expected to be revised soon) the authors define pollen as "Male sex cells produced in anthers of flowers. Powderlike and composed of many grains, they are gathered and used by honey bees for food as a source of protein. A good mix of many different pollens is essential for adequate nutrition."
Humans use pollen as a supplement or as a way to desensitize the effects of hay fever. If you pick up a jar of pollen granules at your local health food store, the label is likely to read "All naturally occurring: vitamins, minerals, amino acids, carotenoids, bioflavonoids, phytosterols, fatty acids, and enzymes" and the like. Then there's the caution: "Bee pollen may cause allergic reactions in some sensitive people."
And the bees? The brood likes it just fine, except when it's toxic (California buckeye pollen is toxic to the larvae and can result in malformed, nonfunctional adults). Pollen contaminated with pesticides can also be life-threatening. Pesticides used on such crops as alfalfa, oranges, cotton, corn and beans can be hazardous to bees.
Meanwhile, a pollen-packing honey bee in flight is a sight to bee-hold.
Pollen-packing honey bee heading toward plum blossoms. (Photo by Kathy Keatley Garvey)
Honey bee adjusts her load. (Photo by Kathy Keatley Garvey)
Honey bee loaded with pollen heading home. (Photo by Kathy Keatley Garvey)