"As the phenomenon known as Colony Collapse Disorder (CCD) continues to plague North American honey bees, apiologists have been scrambling to find both the cause and the cure for the disappearance of millions of insects.

According to a report in the open access journal Genome Biology, new research from a group of Canadian scientists may have found a major culprit responsible for the disorder: a parasitic mite known as Varroa destructor.

Researchers found that the tiny mites suck the blood of larval and adult bees, which leaves them weak and more susceptible to infections. This parasitic relationship also increases the risk of viral disease among hosts that already have a relatively weak immune system due to a low number of immunity genes compared to more solitary insects like flies.

The researchers also report that the bees are not without recourse in their battle against the V. destructor menace. At a research apiary in Grand Forks, British Columbia, members of the honey bee colonies were observed removing diseased or parasitized larvae from their brood cells and removing mites from remaining larvae.

This behavior prompted the research team to examine protein differences in larvae and adults that could serve as a signal for the hygienic insects. After analyzing approximately 1,200 proteins, the team found that several proteins that were associated with both the opening of brood cells and the elimination of larvae. Some of the proteins they identified were signals the probably assisted the adult bees in locating infected larvae in a brood.

In addition to identifying the key proteins in adult bees that are responsible for their hygienic behavior, experts spotted a protein in damaged larvae that could also play a key role and uncovered several other larval proteins that help fight off or resist infection.

The study’s lead scientist said he hoped the identification of these proteins could translate into more robust and disease resistant bee colonies."


Dying Honey Bees Fight Colony Collapse With Resistance Genes
by Brett Smith for redOrbit.com

"Honey-bees are known for their sting, but scientists have now discovered they can also bite.

Bees resort to biting when faced with pests, such as parasitic mites, that are too small to sting.

Close study of the biting behaviour has revealed that they secrete a chemical in their bite that stuns pests so they are easier to eject from a colony.

Tests suggest the chemical could also have a role in human medicine, as a local anaesthetic."



Honey-bees found to have bite that stuns
from BBC © 2012

"A parasitic mite has helped a virus wipe out billions of honeybees throughout the globe, say scientists.

A team studying honeybees in Hawaii found that the Varroa mite helped spread a particularly nasty strain of a disease called deformed wing virus.

The mites act as tiny incubators of one deadly form of the disease, and inject it directly into the bees' blood.

This has led to 'one of the most widely-distributed and contagious insect viruses on the planet'.

Dr Martin explained to BBC Nature that most viruses were not normally harmful to the bees, but the mite 'selected' one lethal strain of one specific virus.

'In an infected bee there can be more viral particles than there are people on the planet,' Dr Martin explained.

'There's a vast diversity of viral strains within a bee, and most of them are adapted to exist in their own little bit of the insect; they get on quite happily.'

But the mite, he explained, 'shifts something'.

In Varroa-infected bees, over time, the vast majority of these innocuous virus strains disappear and the bees' bodies are filled with one lethal strain of deformed wing virus.

And when it comes to viral infection, it's the sheer quantity that kills; each viral particle invades a cell and takes over its internal machinery, turning the bee's own body against itself.

Although it is not clear exactly why this strain thrives in mite-infected bees, Dr Martin explained that it could be the one virus best able to survive being repeatedly transmitted from the mites to the bees and back, as the mites feed on the bees' blood."

Honeybee virus: Varroa mite spreads lethal disease
By Victoria Gill

"Felix Munk gets stung up to 20 times a day but that doesn't stop him from regularly clambering up to the roof of the Vienna Opera and other city landmarks to check on the bees living above the heads of unsuspecting music lovers and government ministers.

Munk is a member of Vienna's Stadtimker, one of a growing number of urban beekeepers' associations who are trying to encourage bees to make their homes in cities, as pesticides and crop monocultures make the countryside increasingly hostile.

Bee populations are in sharp decline around the world, under attack from a poorly understood phenomenon known as colony collapse disorder, whose main causes are believed to include a virus spread by mites that feed on haemolymph - bees' 'blood'.

As well as making honey, bees are important pollinators of flowering plants, including many fruits and vegetables. A 2011 United Nations report estimated that the work of bees and other pollinators was worth 153 billion euros a year.

'Bees do very well in cities,' says Stephen Martin of the University of Sheffield, an expert on the deadly Varroa mite that has wrought destruction on honey bee colonies around the world since being exported from its native Asia in the 1960s.

'There are lots of plants and flowers in cities for bees to live on. Keeping them on rooftops is a great idea because it keeps them out of the way of people.'"

Vienna pitches urban chic to beleaguered bee colonies
By Georgina Prodhan

"The parasitic Varroa mite attacks the honey bee, Apis mellifera L., by feeding on its hemolymph, which is the combination of blood and fluid inside a bee. Colonies can be weakened or killed, depending on the severity of the infestation. Most colonies eventually die from varroa infestation if left untreated.

Varroa-sensitive hygiene (VSH) is a genetic trait of the honey bee that allows it to remove mite-infested pupae from the capped brood—developing bees that are sealed inside cells of the comb with a protective layer of wax. The mites are sometimes difficult for the bees to locate, since they attack the bee brood while these developing bees are inside the capped cells.

ARS scientists at the agency’s Honey Bee Breeding, Genetics and Physiology Research Unit in Baton Rouge, La., have developed honey bees with high expression of the VSH trait. Honey bees are naturally hygienic, and they often remove diseased brood from their nests. VSH is a specific form of nest cleaning focused on removing varroa-infested pupae. The VSH honey bees are quite aggressive in their pursuit of the mites. The bees gang up, chew and cut through the cap, lift out the infected brood and their mites, and discard them from the broodnest."

Honey Bees Selected by ARS Toss Out Varroa Mites
By Alfredo Flores

"The varroa mite is causing a highly contagious virus to proliferate in honeybee colonies here and around the globe, Hawaii and British researchers have found.

Researchers from the University of Hawaii, the University of Sheffield in South Yorkshire, the British Marine Biological Association, and the British Food and Environmental Research Agency studied the pest in Hawaii.

Their research, reported Friday in the journal Science, showed how the varroa mite caused the virus, a known pathogen, to increase its frequency among honeybee colonies to 100 percent from 10 percent."


Virus poses added threat to isle honey bees

By Leila Fujimori

  "Traditionally, varroa mites have been controlled chemically. In fact, chemical-based, in-hive treatments have followed varroa everywhere the mite has been introduced. Pyrethroids, organophosphates, essential oils, and organic acids have been used by many countries to control varroa. Initially, the pyrethroid fluvalinate showed high levels of efficacy (>90%) against varroa mites. However, varroa mites have a demonstrated ability to become quickly resistant to this and other synthetic acaricides. This has made many acaricides useless in areas where varroa resistance to chemicals has developed. Further exacerbating this is the issue that many of the synthetic chemicals used inside of bee colonies to control varroa double as insecticides in other pest-management schemes. So, varroa mites have required beekeepers to put insecticides into insect colonies, the results of which are only just beginning to be understood. The effects of chemical varroa treatments on honey bees include reduced longevity of queen bees, reduced sperm loads in and longevity of drones, brood death, and reduced queen laying patterns. Many more effects are believed to exist.

"Because of the reduced efficacy of chemicals used to control varroa, attention has turned to the application of non-chemical methods for limiting varroa populations. For example, varroa are attracted disproportionately to drone brood. This has led some beekeepers to practice selective removal of drone brood from bee colonies after it has been capped. This practice eliminates a cohort of varroa mites from colonies. Also popular is the use of screened bottom boards to lower varroa mite populations. Although its level of efficacy is debated, replacing solid bottom boards of a bee colony with screen mesh can reduce varroa populations as much as 14%.

"Without question, the most significant advancement toward controlling varroa non-chemically has come in the realm of bee breeding. A number of bee defensive responses to varroa have been identified and selected for in natural and artificial breeding programs; the most notable of these are hygienic behavior and grooming behavior. Bees that exhibit grooming behavior use their legs to comb themselves. They do this both to themselves and to other bees in the colony. This behavior can increase the number of varroa that fall off of the bees, thus lowering the number of varroa in a colony.

"Hygienic behavior is the most studied of all of the natural defenses against varroa. Although it is not a behavior specifically targeting varroa, its manifestation can lower varroa mite populations within a colony. Bees that are hygienic can detect many problems that affect brood (American foulbrood, varroa, chalkbrood, etc.), even if the brood is capped, and remove the affected brood. Because varroa mites go into cells immediately prior to the cell being capped, hygienic bees are given little time to 'find' varroa before the cell is capped. As a result, hygienic bees have a refined ability to detect varroa in capped cells, remove the capping, and abort the brood. Often, this behavior can lead to the death of the mite, thus lowering varroa populations. It is interesting to note, a heightened form of hygienic behavior called 'varroa sensitive hygiene' (VSH) has been found in some bees. VSH bees are able to detect varroa in capped cells and remove only those varroa that are reproducing."


Publication Number: EENY-473
Authors: James D. Ellis and C.M. Zettel Nalen, University of Florida

"The blood-sucking varroa mite is endemic in many honey bee colonies and transmits lethal viruses to the bees.
Novel ways to tackle varroa are needed because mites are becoming resistant to existing chemical treatments.
The cash will be used to extend a completed study that showed how to target specific genes used by the mite.
So far, said Dr Alan Bowman of the University of Aberdeen who is leading the project, this "knock-down" approach has only been used to home in on non-lethal genes.
'The next step is to continue finding which are the best genes that will kill them quickly at very low doses and then we'll move on out to field trials when we'll be working with the National Bee Unit,' said Dr Bowman.
The knock-down technique attempts to trick part of the bug's immune system into thinking that one of its genes is a virus.
Typically the part of the immune system being subverted only tackles external threats in the form of a certain types of RNA-based viruses.
Dr Alan Bowman University of Aberdeen As active genes also use RNA, it should be possible to subvert this defence mechanism by making it think one of the genes keeping the mite living is actually an invader."

Cash to help fight pervasive honey bee pest
BBC News Science and Environment