Thursday, May 24, 2007
Monday, May 14, 2007
Why bees are disappearing
May 18, 2005
BEE MITES SUPPRESS BEE IMMUNITY,
OPEN DOOR FOR VIRUSES AND BACTERIA
Science Daily — A non-native bee mite is causing the dramatic and sudden collapse of bee colonies across the country, but Penn State researchers believe they have found the combination of factors that triggers colony deaths which includes suppression of the bee immune system by the mites.
The Varroa destructor mite is a honey bee parasite that feeds much like a tick on the body of a bee. The mites are about the size of a pin head, dark brown in color and visible on close inspection.
This bee mite probably arose in the Eastern or Chinese Honey Bee population and hopped over to the United States in 1987. They quickly infested western or European honey bees. One sign of infection is the presence of bees with deformed wings. Also, sometimes seemingly healthy colonies become ill and the complete hive collapses in about two weeks.
"The native Chinese bees do not have the same problems," says Dr. Xiaolong Yang, post doctoral researcher in entomology and plant pathology, who raised bees in China. "I do not recall seeing deformed wing bees in the Chinese bee. Chinese honey bees have grooming behavior which can remove the mites from the bees. They get rid of the mites."
While researchers know that the Varroa mite is behind the death of bee colonies, the mechanism causing the deaths is still unknown. Yang and Dr. Diana L. Cox-Foster, Penn State professor of entomology, now believe that a combination of bee mites, deformed wing virus and bacteria is causing the problems occurring in hives across the country.
"Once one mite begins to feed on a developing bee, all the subsequent mites will use the same feeding location," says Cox-Foster "Yang has seen as many as 11 adult mites feeding off of one bee. Other researchers have shown that both harmful and harmless bacteria may infect the feeding location."
Deformed wing virus is endemic among honey bees in the U.S., although when the European bees became historically infested with this virus, is unknown. However, simply having deformed wing virus does not cause bees to emerge from the pupa state with deformed wings, nor does it cause colony deaths.
"A group of Japanese researchers found that a virus that is 99 percent the same as deformed wing, appears in in the brains of aggressive guard bees," says Cox-Foster. "Guard bees that are aggressive better protect the hive, so there may be some positive effect in this virus that allows it to persist in a colony."
The combination of bee mite infestation and deformed wing virus does cause deformed wings in about a quarter of the emerging bees. This, however, does not lead to sudden hive collapse. Something else is involved that makes bee mites so harmful to bee colonies.
The Penn State researchers report their findings in today's (May 17) online version of the Proceedings of the National Academy of Science.
Yang and Cox-Foster looked at how bee mites affect the bee immune system. They injected heat-killed E. coli bacteria into virus-infected bees that were either infested with bee mites or mite free. The dead bacteria was used to trigger an immune response in the bees in the same way human vaccines cause our bodies to produce an immune response. They checked the bees for production of chemicals that disinfect the honey and for other immunity related chemicals.
They also measured the amount of virus in each bee. Surprisingly, they found that the virus in mite-infested bees rapidly increased to extremely high levels when the bee was exposed to the bacteria. The virus levels in mite-free bees did not change when the bee was injected with bacteria.
One chemical, GOX or glucose oxidase, is put into the honey by worker bees and sterilizes the honey and all their food. If bees have mites, their production of GOX decreases.
"As mites build up, we suspect that not as much GOX is found in the honey and the honey has more bacteria," says Cox-Foster. "It is likely that the combination of increased mite infestation, virus infection and bacteria is the cause of the two-week death collapse of hives."
The mites suppressed other immune responses in the bees, leaving the bees and the colonies more vulnerable to infection. The bee mites transfer from adult bees to late stage larva. The virus can be transferred through many different pathways.
"This system is important not only because of what the mites are doing to honey bee populations in the U.S., but because it can be used as a model system for exploring what happens to viruses in animal or human populations," says Cox-Foster. "If we view the colony as a city, then we have a variety of infection modes -- queen to eggs, workers to food supply, bee to bee, and parasite to bee."
__________
The Pennsylvania Department of Agriculture supported this work.
Note: This story has been adapted from a news release issued by Penn State.
Friday, May 11, 2007
Laundry on the line
April 19th was National Hanging Out Day, a day which was created to demonstrate how it is possible to save money and energy by using a clothesline. I missed the day, but learned about it from Susan's Patchwork Reflection blog.
When I was a girl, I hung clothes out to dry because my red-haired mother's fair skin would burn in even a few minutes of sun. That excuse didn't work in the winter when it was so cold my fingers felt frozen by the wet clothes.
"Air-drying our clothes would reduce our dependence on environmentally and culturally costly energy sources," according to Project Laundry List. So why don't we do it anymore? I remember the frozen fingers, but I also live in an apartment. There's no way I could dry a load of wash on my postage-stamp-sized patio. Some places forbid clotheslines, but would it be worthwhile to make changes so more of us could hang out clothes? Or is it just too easy to throw the clothes from the washer into the dryer?
Read more about this at Project Laundry List.
Tuesday, May 1, 2007
Living off the grid
DON'S SOLAR SCOOTER
Don Dunklee offers a set of plans for a street legal, affordable, and dependable solar-powered scooter. The PV panels fold in for driving and out for charging. Don rides his scooter five miles to work each day and folds out the panels for charging the battery while the scooter is parked at work. And he has now been doing this for 2-3 years and has traveled thousands of miles using solar power. What will they think of next!!!??? See another photo and read about it here: http://www.builditsolar.com/Projects/PV/pvscooter.htm
GERTIE THE GAS GUZZLER
Andy Baird took up full-time RVing and converted Gertie the Gas Hog, which once got 8mpg, into a solar-powered home on wheels. He spends less on gas and electricity than he did when he drove to and from work in a Honda. And now he leisurely meanders north in the spring and south in the fall. All because he solar-paneled Gertie. Check it out here: http://www.andybaird.com/travels/saving-the-earth.htm
NANO-TOWER DESIGN
Better design, better results, right? Not yet. The Georgia Tech Research Institute unveiled a new solar panel in April with a different design. The solar panels I've seen are flat, but the new design has "an array of nano-towers" that are like microscopic blades of grass. That adds surface area and thus traps more sunlight, resulting in a big jump in current generated, about 60 times more than traditional solar cells. Wow, I'm impressed. But now comes the part that confuses me: to generate electricity, a cell has to churn out voltage as well as current. And this invention falls short because of "too much resistance within the cell to produce the type of electricity that's needed." Surely, if these folks keep working on this new design, they'll find a way to make it work better. Read the full aticle: http://www.ibtimes.com/articles/20070411/techbit-better-solar-panel.htm
Don Dunklee offers a set of plans for a street legal, affordable, and dependable solar-powered scooter. The PV panels fold in for driving and out for charging. Don rides his scooter five miles to work each day and folds out the panels for charging the battery while the scooter is parked at work. And he has now been doing this for 2-3 years and has traveled thousands of miles using solar power. What will they think of next!!!??? See another photo and read about it here: http://www.builditsolar.com/Projects/PV/pvscooter.htm
GERTIE THE GAS GUZZLER
Andy Baird took up full-time RVing and converted Gertie the Gas Hog, which once got 8mpg, into a solar-powered home on wheels. He spends less on gas and electricity than he did when he drove to and from work in a Honda. And now he leisurely meanders north in the spring and south in the fall. All because he solar-paneled Gertie. Check it out here: http://www.andybaird.com/travels/saving-the-earth.htm
NANO-TOWER DESIGN
Better design, better results, right? Not yet. The Georgia Tech Research Institute unveiled a new solar panel in April with a different design. The solar panels I've seen are flat, but the new design has "an array of nano-towers" that are like microscopic blades of grass. That adds surface area and thus traps more sunlight, resulting in a big jump in current generated, about 60 times more than traditional solar cells. Wow, I'm impressed. But now comes the part that confuses me: to generate electricity, a cell has to churn out voltage as well as current. And this invention falls short because of "too much resistance within the cell to produce the type of electricity that's needed." Surely, if these folks keep working on this new design, they'll find a way to make it work better. Read the full aticle: http://www.ibtimes.com/articles/20070411/techbit-better-solar-panel.htm
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