Varroa Mites Feed On The Fat Bodies Of Honey Bees, Not The Hemolymph. This Is Important!

Catch The Buzz By Dennis O’Brien January 30, 2019

cross section of honey bee abdomen.jpg

An image showing a cross section of a varroa mite feeding on a honey bee’s abdominal cavity is one of several ARS microscopy images changing what we know about how mites damage honey bees.

Research by scientists at the Agricultural Research Service (ARS) and the University of Maryland released today sheds new light — and reverses decades of scientific dogma — regarding a honey bee pest (Varroa destructor) that is considered the greatest single driver of the global honey bee colony losses. Managed honey bee colonies add at least $15 billion to the value of U.S. agriculture each year through increased yields and superior quality harvests.

The microscopy images are part of a major study showing that the Varroa mite (Varroa destructor) feeds on the honey bee’s fat body tissue (an organ similar to the human liver) rather than on its “blood,” (or hemolymph). This discovery holds broad implications for controlling the pest in honey bee colonies.

The study was published on-line Jan. 15 and in today’s print edition of the Proceedings of the National Academy of Sciences. An image produced by the ARS Electron and Confocal Microscopy Unit in Beltsville, Maryland is on the cover of today’s journal.

Varroa mites have been widely thought to feed on the hemolymph, of honey bees (Apis mellifera) because of studies conducted in the 1970’s which used outdated technology. But today’s collaborative study, by University of Maryland and ARS researchers at the ARS Electron and Confocal Microscopy Unit, offers proof of the mite’s true feeding behavior. Through the use of electron microscopy, the researchers were able to locate feeding wounds on the bee caused by the mites, which were located directly above the bee’s fat body tissue. The images represent the first direct evidence that Varroa mites feed on adult bees, not just the larvae and pupae.

In addition, University of Maryland researchers conducted feeding studies and found that Varroa mites that were fed a diet of fat body tissue survived significantly longer and produced more eggs than mites fed hemolymph. The results show, mites fed a hemolymph-only diet were comparable to those that were starved. Thus, proving conclusively that the Varroa mite feeds primarily on the fat body consumed from bees.

The results are expected to help scientists develop more effective pesticides and other treatments to help bees cope with a mite known to spread at least five viruses. They also help explain why Varroa mites have such detrimental effects on honey bees, weakening their immune systems, and making it harder for them to store protein from pollen and survive through the winter.

The study was part of the Ph.D. thesis of Samuel D. Ramsey from the University of Maryland and was conducted in collaboration with ARS researchers and study co-authors Gary Bauchan, Connor Gulbronson, Joseph Mowery, and Ronald Ochoa.

The study can be found here.

The Agricultural Research Service is the U.S. Department of Agriculture’s chief scientific in-house research agency. Daily, ARS focuses on solutions to agricultural problems affecting America. Each dollar invested in agricultural research results in $20 of economic impact.

Catch The Buzz: Varroa mites feed on the fat bodies of honey bees

Also see: https://www.losangelescountybeekeepers.com/blog/2019/1/15/honey-bee-parasites-feed-on-fatty-organs-not-blood

Accidental Discovery Could Save Bees From Their Greatest Threat

Real Clear Science     By Ross Pomeroy     January 15, 2018

Agricultural Research ServiceGerman scientists primarily based out of the University of Hohenheim have stumbled upon a simple solution that could deal a blow to honeybees' greatest threat. They've found that a tiny dose of the compound lithium chloride kills Varroa destructor mites without harming bees.

The scientists detailed their incredible findings in the January 12th publication of Scientific Reports.

V. destructor, more commonly known as the Varroa mite, is a scourge of honeybees across the globe. Upon infiltrating a colony, the mites latch on to bees, sucking their hemolymph (essentially blood) and spreading the diseases they carry. According to the USDA, 42 percent of commercial hives in the U.S. were infested in summer 2017, and 40 percent of beekeepers said the parasite seriously harmed their colonies. By comparison, only 13 percent reported harm from pesticides.

Chemical compounds exist to combat the parasites but they are outdated and growing increasingly ineffective, the researchers write, adding that no new active compounds have been registered in the last 25 years.

The dearth of options prompted scientists at The Hebrew University of Jerusalem to experiment with a technique called RNA interference. In their study, they fed bees double-stranded RNA via a sugar solution to knockout vital genes in Varroamites. The mites ingested the lethal RNA via bees' hemolymph and subsequently died.

Inspired by those results, the German researchers sought to replicate them by repeating the experiment with slightly tweaked methods. Indeed, mites infesting bees that were fed sugar water with the designed RNA rapidly died, but so did mites in a control group given another RNA that should have been ineffective. The astonishing results prompted the researchers to suspect that the lithium chlorideused to produce the RNA – and thus present in the sugar water – was actually killing the parasites. A battery of subsequent examinations confirmed their hypothesis.

The scientists then carried out numerous experiments testing lithium chloride against Varroa mites, including ones that approximated field studies. They found that feeding honeybees minuscule amounts of lithium chloride (at a concentration of no more than 25 millimolar) over 24 to 72 hours wiped out 90 to 100 percent of Varroa mites without significantly increasing bee mortality. (Below: The figure shows the surviving proportion of bees and mites fed lithium chloride compared to those not fed lithium chloride.) Ziegelmann et al. / Scientific Reports

According to the researchers, lithium chloride could be put to use very quickly as it is easily applied via feeding, will not accumulate in beeswax, has a low toxicity for mammals, and is reasonably priced. However, wider studies on free-flying colonies testing long-term side effects are required first, as well as analyses of potential residues in honey.

Francis Ratnieks, a Professor of Apiculture at the University of Sussex, expressed skepticism about the new finding.

"We can kill 97% of the Varroa in a brood less hive with a single application of oxalic acid, which takes five minutes to apply and is already registered and being used by beekeepers," he told RCScience via email. "I think it will be difficult in practice to apply lithium salts to colonies to kill varroa and get the same level of control... There are also the wider issues of registration and potential contamination of the honey with a product that would not normally be there."

It should be noted that studies have shown oxalic acid to be inconsistent at managing mites during the summer months as well as in colonies with capped broods

Regardless, the Hohenheim researchers are pressing forward. They're already speaking with companies to get a lithium chloride treatment refined, approved, and in the hands of beekeepers.

"Lithium chloride has potential as an effective and easy-to-apply treatment for artificial and natural swarms and particularly for the huge number of package bees used for pollination in the United States," they conclude.

Source: Bettina Ziegelmann, Elisabeth Abele, Stefan Hannus, Michaela Beitzinger, Stefan Berg & Peter Rosenkranz. "Lithium chloride effectively kills the honey bee parasite Varroa destructor by a systemic mode of action." Scientific Reports 8, Article number: 683 (2018) doi:10.1038/s41598-017-19137-5

*Article updated 1/15 to include Professor Ratnieks' statement and to include information about oxalic acid.

*An earlier version of this article mistakenly reported that the researchers are based out of the University of Hoffenheim. They are from the University of Hohenheim.

https://www.realclearscience.com/quick_and_clear_science/2018/01/15/accidental_discovery_could_save_bees_from_their_greatest_threat.html

Related articles/info:
http://scientificbeekeeping.com/home/news-and-blogs/

http://www.beesource.com/forums/showthread.php?341995-Lithium-chloride-as-miticide&s=cf01c15735e4ecac52336121d381e000

https://badbeekeepingblog.com/2018/01/17/have-you-lithium-chlorided-your-bees-yet/

Asia’s Bee Mites Alarmingly Resistant

AsianScientist       Asian Scientist Newsroom     March 7, 2017

A study of the Tropilaelaps mercedesae genome has revealed that conventional mite control strategies might not work.

The genome of the parasitic bee mite Tropilaelaps mercedesae suggests that existing methods to prevent bee colony collapse might be ineffective. These findings have been published in GigaScience.

Although there are many potential causes for the decline in honey bee colonies, pathogens and parasites of the honey bee, particularly mites, are considered major threats to honey bee health and honey bee colonies. The bee mite T. mercedesae is honey bee parasite prevalent in most Asian countries, and has a similar impact on bee colonies that the globally present bee mite Varroa destructor has. With the global trade of honey bees, T. mercedesae is likely become established world-wide.

To preempt the impact of T. mercedesae infestation, an international team of researchers from Jiaotong-Liverpool University sequenced its genome and compared it to the genome of free-living mites.

 

As opposed to the free-living mites, T. mercedesae has a very specialized life history and habitat that depends strictly on the honey bee inside a stable colony. The researchers found that the T. mercedesae genome has been shaped by interaction with the honey bee and colony environment.

Interestingly, the authors found that the mite does not rely on sensing stimulatory chemicals to affect their behavior. The researchers noted that this discovery meant that, “control methods targeted to gustatory, olfactory, and ionotropic receptors are not effective.” Instead, control measures will have to use other targets when trying to disrupt chemical communication.

“There will be a need to identify targets for biological control,” they added.

Furthermore, the researchers found that T. mercedesae is enriched with detoxifying enzymes and pumps for the toxic xenobiotics, which help them quickly acquire resistance to miticides.

However, the study also revealed a potential alternative to miticides. The researchers found that Rickettsiella grylli commonly infect T. mercedesae, suggesting that targeting these bacteria might be one way to control the mite population.

They also found that R. grylli was involved in horizontal gene transfer of Wolbachia genes into the mite genome. Wolbachia is a bacteria that commonly infects arthropods, but is not present in T. mercedesae.

Although up to a horizontal gene transfer has been detected in as many as a third of all sequenced arthropod genomes, this is the first example of horizontal gene transfer in mites and ticks, the authors noted. Since Wolbachia bacteria do not currently infecting the mites, these findings indicate that Wolbachia was once a symbiont for T. mercedesae or its ancestor but has been replaced with R. grylli-like bacteria during evolution, they added.

The extent of honey bee colony destruction remains a complex problem, but one that has an extensive impact crop productivity since honey bees are needed for pollination of a variety of plants. Indeed, in several places in China, farm workers have begun to carry out manual pollination to maintain high crop yield in orchards. Thus, research and resources to help combat this global threat are needed now. These genome, transcriptome, and proteome resources from the T. mercedesae study add another weapon in the fight to save bee colonies.

The article can be found at: Dong et al. (2016) Draft Genome of the Honey Bee Ectoparasitic Mite, Tropilaelaps Mercedesae, is Shaped by the Parasitic Life History.” ——— Source: GigaScience. Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

Read more from Asian Scientist Magazine at: https://www.asianscientist.com/2017/03/in-the-lab/tropilaelaps-mercedesae-genome-bee-mite/

When Varroa Mites Hitch a Ride

Bug Squad    By Kathy Keatley Garvey   March 1, 2016

Varroa mite on a honey bee (drone) pupa. (Photo by Kathy Keatley Garvey)Those blood-sucking varroa mites (Varroa destructor) are considered the No. 1 enemy of beekeepers. In powerful numbers and weakened colonies, they can overwhelm and collapse a hive.
 

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:

  1.  Are the nutrients of the substitute host close enough to those of honey bees to support immature mite development? 
  2. 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? 
  3. 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 destructorreproduction.

Sounds like a good research project!

A varroa mite attached to a honey bee forager. It's the reddish brown spot near the wing. The bee is foraging on lavender. Photo: Kathy Keatley Garvey http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=20360

Tracking a Parasite that Turns Bees Into Zombies

The New York Times    By Nicholas St. Fleur    February 25, 2016

A female parasitic Apocephalus borealis fly about to infect a honey bee with its eggs. Credit Christopher Quock

Call it “The Buzzing Dead.” Infestations of what scientists have dubbed “zombie bees” have spread across both the West and East coasts in recent years.

The honeybee hordes, while not actually undead, are the unwilling hosts to a parasite infection that researchers think drives the drones to act erratically, or “zombielike,” in the moments before they die.

To better understand the parasitized swarms, John Hafernik, an entomologist at San Francisco State University has recruited people countrywide to join his hunt.

“The big question for us was, ‘Is this a San Francisco thing?’ Or something that is taking place all over the country that has not been noticed by biologists before,” he said.

Since he began the project four years ago, he has concluded the answer is the latter. Volunteers have helped identify infected honeybees in California, Washington and Oregon as well as Vermont, Pennsylvania and New York. More than 800 bee observations have been uploaded to the ZomBee Watch online database.

Dr. Hafernik first discovered something eerie was happening to the bees on his campus in 2008 when he stumbled upon several of them staggering in circles along the sidewalk. For weeks he picked a few up and placed them in a glass vial with plans to feed them to his pet praying mantis.

One day he came across a vial he had forgotten on his desk for a couple of weeks. The bees inside were dead, but the vial was overwhelmed with small brown fly pupae. He came to the realization that the bees were parasitized.

 Fly maggots bursting from a parasitized honey bee. Credit John Hafernik

After further exploration across San Francisco Bay, he and his colleagues found several bees that were also behaving strangely. They would fly from their hives at night, which was something bees would normally never do, and then circle around a light fixture. After their nocturnal dance the bees would drop to the ground and start walking strangely. They were succumbing to their overlord, larvae of the fly Apocephalus borealis.

The life cycle of the parasitic fly is straight from a horror story. The female fly uses something called an ovipositor, which is like a hypodermic needle, to inject her eggs into the abdomen of the honeybee.

About a week later the larvae lurking within the abdomen wriggle into the bee’s thorax and start liquefying and devouring its wing muscles. Then, like in the movie “Alien,” they burst through the bee’s body, erupting from the soft space between its head and shoulder area.

“As far as we know this is a death sentence,” Dr. Hafernik said. “We don’t know any bees that have survived being parasitized by these maggots.”

As many as 80 percent of the hives that Dr. Hafernik examined in San Francisco Bay had been infected. Understanding more about how the infection spreads is important, he said, because although the infestations are not the main driver behind honeybee declines across the country, they could help collapse an already vulnerable colony.

http://www.nytimes.com/2016/02/26/science/tracking-a-parasite-that-turns-bees-into-zombies.html?smid=tw-nytimesscience&smtyp=cur&_r=1

Interaction between Varroa destructor and imidacloprid reduces flight capacity of honeybees

Phys.org    December 18, 2105

Parasitic mites Varroa destructor together with the pesticide imidacloprid hamper bees in their search for pollen. The pesticide and the bee parasite reduce the honeybees' flight capacity, causing bee colonies to weaken and possibly even collapse. This was concluded by researchers from Wageningen University & Research Centre in their article in Proceedings of the Royal Society B.

Honeybees fly shorter distances when they originate from colonies with many Varroa mites, the researchers note. The distances they travel are even smaller when those colonies were also exposed to the chemical pesticide imidacloprid in a dose that bees may encounter in the field. The effect of the Varroa  was found to be larger than that of imidacloprid, but the pesticide increases the negative effect of the parasite.

Colony losses

The study shows that the ability of the colony to collect food may be hampered due to imidacloprid in combination with the parasitic mite Varroa destructor. When this effect lasts long enough, it may lead to weakening and ultimately collapse of the colony.

The role of the Varroa mite in winter mortality of  is well known among beekeepers. A heated debate has been going on for several years already about the role of neonicotinoid pesticides, like imidacloprid. In previous studies on the effects of these pesticides on , often individual bees were exposed to relatively high doses of the pesticide. In this study, however, entire bee colonies were exposed to both the Varroa mite and imidacloprid for several months.

Flight mill

Bee in flight mill. Credit: C. van Dooremalen, Wageningen URThe researchers used  foraging bees for the experiment. These were caught when returning to their colony with pollen on their hind legs. From this, the researchers deduced that these bees had fetched pollen at least once successfully. Because 'very sick' bees probably not even become a foraging bee, this means that the researchers rather underestimated than overestimated the impact of the Varroa mite and imidacloprid on individual bees in these colonies.

The flight capacity of the bees was tested in a flight mill. Travelled distance and the speed of the bees were measured. To standardize the flight measurements, the  were given a fixed amount of fuel in the form of sugar water beforehand.

Varroa mites (chesnut) on bees' back. Credit: Cornelissen, Wageningen URExplore further: Use of imidacloprid - common pesticide - linked to bee colony collapse

More information: Lisa J. Blanken et al. Interaction between and imidacloprid reduces flight capacity of honeybees , Proceedings of the Royal Society B: Biological Sciences (2015). DOI: 10.1098/rspb.2015.1738 

Journal reference: Proceedings of the Royal Society B

Read more at: http://phys.org/news/2015-12-interaction-varroa-destructor-imidacloprid-flight.html#jCp

Nosema Ceranae

IBRA (International Bee Research Association) FB Post   December 12, 2015

Nosema ceranae is a single cell infection in honey bees. It was said to cause 20,000 colony losses in Salamanca, Spain.

Molecular biology techniques have been used to explore how the honey bee cell reacts to N. ceranae infection. A team of researchers from China and the US (including IBRA trustee Jay Evans) compared bees with and without an infection - and looked at what was going on inside the cell. They found 17 micro-RNA changes when a honey bee cell is infected with N. ceranae. Although we don't yet fully understand the picture, it is a start.

The science bit
DNA forms the blueprint or architect's plans for a cell; DNA holds all the information needed to make a fully functional cell.As need arises, those plans are carried in chunks of text (called messenger-RNA) over to the cellular processing centre so the "stuff that needs to be made" or the "something that needs to be done" will happen.

Micro-RNA binds (or sticks) to unused messenger-RNA so it will be broken down and the message it carries cannot be used. Simply put, microRNA is a "control switch." Micro-RNA controls many things including how cells grow and develop (developmental processes) and normal day to day functions (physiological processes).

So what?
Somehow N. ceranae infection changes the profile of micro-RNa control switches. This leads to a change in the gene-messages being used and ultimately changes what is going on in the cell. The researchers found several chemical pathways were affected - with faster trans-membrane transport and cell metabolism.

Why does it matter?
It may be the faster processes makes more resources available for the N.ceranae to reproduce in bee midgut epithelial cells. It may also explain why honey bees with Nosema need more sugar water to fuel a faster rate of metabolism. However there is much still to be learned about how these changes happen and whether this response takes place only for N.ceranae infections... or always happens when there is an infection.

How will this help beekeepers?
Well, it won't help us yet.. but it gives an insight to how an infection works in honey bees and by understanding that we might be able to work out how to control Nosema in the future.

Find out more about Nosemosis here
http://www.nationalbeeunit.com/index.cfm?pageid=191

Find the free to view scientific paper here
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4664923/

Image: The photo comes from the article "Does Nosema ceranae cause Colony Collapse Disorder?" by Robert Paxton, published in the Journal of Apicultural Research in 2010:http://www.tandfonline.com/doi/abs/10.3896/IBRA.1.49.1.11…

Oxalic Acid Treatment - Trickle Method

Bee Craft B-kids

Photo: BBKAOxalic Acid Treatment - Trickle method

It is easy to forget about varroa mites at this time of year but you do so at your peril!

You can use the oxalic acid treatment only when the colony is broodless, ie. in early winter (or on a newly collected swarm). The aim of treating in winter is to reduce the varroa infestation level to an absolute minimum so that no further treatment will be necessary before late summer. Oxalic acid is an anti varroa treatment method which leaves no residues in hive products, it is a natural organic substance and effectiveness is over 90%.

It is important to make sure your colony is broodless as the acid will only kill mites on the bees, not those on larvae in the honeycomb cells. How to tell when brood rearing has finished? Brood rearing in autumn is influenced by apiary location, but more so by the weather. The British weather has been unseasonably mild lately but the first night frosts will cause the queen to stop egg laying. Three weeks later the colony will be brood free. At this time the oxalic acid trickle method is most effective.

The treatment is carried out using a warm sugar syrup solution at an oxalic acid concentration of 3.5% applied using a syringe or some other suitable device. This can be purchased ready mixed from your beekeeping equipment supplier. 5ml (no more!) of the acid mixture should be trickled onto each seam of bees in each occupied chamber (seam = the space occupied by bees between two frames). This procedure is most easily accomplished when the bees are clustering, so choose a fine, still day in December or early January when temperatures are at or around 0C. The removal of the hive roof and crown board to facilitate the treatment has no detrimental effect on the bees as long as you carry out the procedure quickly!

Before treating, remember that not every colony needs to be treated. A check on the natural mite fall about now is advised. Insert the removable floor and note the natural mite fall a week later. If the fallen mites are light coloured there is still emerging brood in the colony! If the mite fall is more than 1 mite per day treatment is recommended, more than 5 mites per day needs immediate treatment. If untreated colonies indicate an average of 1 mite per day in November, this indicates that there are still some hundreds of mites in the colony.

The treatment must be administered only once. Repeated applications are not tolerated well by the bees and are pointless anyway in a brood free colony.

NB. Oxalic acid treatment can also be applied using a vaporiser.

From Bee Carft B-kids 12/5/15 FB Post: https://www.facebook.com/BKids.BeeCraft/?fref=nf

EPA Registers New Biochemical Miticide to Combat Varroa Mites in Beehives

   September 30, 2015

EPA has registered a new biochemical miticide, Potassium Salts of Hops Beta Acids (K-HBAs), which is intended to provide another option for beekeepers to combat the devastating effects of the Varroa mite on honey bee colonies and to avoid the development of resistance toward other products. Rotating products to combat Varroa mites is an important tactic to prevent resistance development and to maintain the usefulness of individual pesticides.

The registrant, a company called Beta Tech Hop Products, derived K-HBAs from the cones of female hop plants, Humulus lupulus. To control mites on honey bees, the product is applied inside commercial beehives via plastic strips.

Varroa mites are parasites that feed on developing bees, leading to brood mortality and reduced lifespan of worker bees. They also transmit numerous honeybee viruses. The health of a colony can be critically damaged by an infestation of Varroa mites. Once infested, if left untreated, the colony will likely die.

This biochemical, like all biopesticides, is a naturally-occurring substance with minimal toxicity and a non-toxic mode of action against the target pest(s). There are numerous advantages to using biopesticides, including reduced toxicity to other organisms (not intended to be affected), effectiveness in small quantities, and reduced environmental impact. 

More information on this registration can be found at www.regulations.gov in Docket ID EPA-HQ-OPP-2014-0375.

Find out about other EPA efforts to address pollinator loss: http://www2.epa.gov/pollinator-protection.

Learn more about biopesticides: http://www.epa.gov/pesticides/biopesticides/.

Read at:  http://goo.gl/ocQXDJ

Oxalic Acid FAQs

Brushy Mountain Bee Farm Blog  September 18, 2015


WHAT IS OXALIC ACID?
Oxalic Acid is a naturally occurring acid found in plants. It became popular in Europe & Canada for treating Varroa Mites in a honey bee hive.

IS IT A LEGAL VARROA TREATMENT IN THE UNITES STATES?Oxalic Acid has been approved by the EPA to treat honey bee colonies in the United States. It must pass state approval before it may legally be sold in each state. This is a continuing process and a list of states that have been approved can be found on our website.

Versions of Oxalic Acid can be found in hardware stores but those have various additives mixed with them that can cause issue with the bees. Also it is illegal to use them for hives.

WHEN IS THE BEST TIME TO USE OXALIC ACID TO TREAT?The most effective time to treat a hive with Oxalic Acid is when a hive has little to no sealed brood. It cannot penetrate capped brood so it will have no effect on the next generation of mites that were left in capped brood. You can treat in the spring and summer but research shows that Oxalic works best in the fall/winter.

WHEN WILL MY HIVE BEE BROODLESS?The best time for a broodless hive is during late fall through the winter. You can also manipulate the hive by caging the queen for 14 days. That keeps her from laying and capping any more brood. 14 days provides enough time to treat your hive and allow the treatment residue to subside before returning the queen to lay brood.

CAN YOU TREAT IN THE SUMMER?While some studies say you can treat honey bees in the summer, there are too many variables that can cause issues during summer treatments. Summertime is usually when the hive is full of capped brood so it could take multiple treatments to reduce all the mites concealed with the brood. Continuous multiple treatments can affect the bees severely.

CAN YOU TREAT DURING A HONEY FLOW?It has not been approved for use during a honey flow. If you have honey supers on the hive you must remove them before treating and leave them off for at least 14 days to give the Oxalic Acid treatment time to be fully cleansed from the hive to avoid contamination of the honey.

HOW CAN IT BE USED TO TREAT?There are three approved methods to treat with Oxalic Acid:
Solution Method:Note: To completely dissolve Oxalic Acid Dihydrate, use warm syrup.Dissolve 35g of Oxalic Acid Dihydrate in 1 liter of 1:1 sugar water (weight : volume). Smoke bees down from the top bars. With a syringe or an applicator, trickle 5 ml of this solution directly onto the bees in each occupied bee space in each brood box. The maximum does is 50ml per colony whether bees are in NUCs, single, or multiple brood chambers.
Under certain unfavorable conditions (e.g. weak colonies, unfavorable overwintering conditions), this application method may cause some bee mortality or overwintering bee loss.
complete kit is available with all the parts you will need for Solution Method (35 grams Oxalic Acid, nitrile gloves, protective goggles, 60mm syringe, and instructions)
Vaporizer Method:Apply only to outdoor colonies with a restricted lower hive entrance. Seal all upper hive entrances and cracks with tape to avoid escape of Oxalic Acid vapor. Smoke bees up from the bottom board. Place 1g Oxalic Acid Dihydrate powder into vaporizer. Follow the vaporizer manufacturer’s directions for use. Insert the vaporizer apparatus through the bottom entrance. Apply heat until all Oxalic Acid has sublimated.
Spraying Package Method:Ensure bees are clustered before applying.Spray broodless package with 1:1 sugar water solution (without Oxalic Acid mixed) at least 2 hours before spraying with Oxalic. This fills their stomachs to reduce ingestion of Oxalic Solution.Mix 1:1 ratio sugar water with 35 grams of Oxalic Acid (same ratio as Solution Method). For a 2 lb package, use 21mL of solution. For a 3 lb package use 31mL solution.Store bees in a cool darkened room for 72 hours before hiving.

HOW MANY HIVES CAN OXALIC ACID TREAT?*All totals calculated from dosage amounts listed in treatment methods above.Solution Method: 20 hivesVaporizer Method: 35 hivesSpraying Package Method: 47 2lb packages & 30 3lb packages

WHAT SAFETY MEASURES SHOULD I TAKE WHEN USING OXALIC ACID?DO NOT let Oxalic Acid make contact with skin, eyes, or be ingested. Wear proper personal protective equipment (rubber gloves, safety goggles, long sleeve shirt) when mixing or distributing Oxalic Acid. If exposure to skin or eyes does occur consult directions and safety sheet for instructions. If severe reaction occurs, call 911. Wash hands, exposed skin, and PPE directly after treatment to avoid contamination.

HOW EFFECTIVE IS OXALIC ACID?The effectiveness of Oxalic Acid treatment can be in excess of 95%, but solution method have a higher efficacy.

HOW MANY TIMES SHOULD I TREAT MY HIVE?You will only want to treat your hive ONCE during the fall/winter. Honey bees have a low tolerance to Oxalic Acid.  Overexposure can cause issues and death in the hive.

As with any other treatment, some bee mortality may occur, especially if hive is already weak. Check your mite count and strength of hive before applying any treatment. If you are uncertain of hive’s strength, you can get a second opinion by asking a local beekeeper or your local bee inspector.

CAN I USE OXALIC ACID WITH OTHER MEDICATIONS?Since it is a naturally occurring chemical, it can be used in conjunction with other non-varroa treatments. DO NOT mix directly with other chemicals while treating.

HOW DO YOU STORE OXALIC ACID?Dried, unmixed Oxalic Acid should be kept in a cool dry place will not expire.Mixed solution can last up to a week at room temperature and a few months if kept in the fridge.
IF THE SOLUTION STARTS TO TURN TAN/BROWN OR SMELL FUNNY DISCARD IMMEDIATELY. DISCOLORATION MEANS AN ALTERNATE CHEMICAL [HYDROXYMETHYLFURFURAL] IS FORMING AND IS TOXIC TO BEES. DISCOLORATION CAN BE CAUSED BY LONG EXPOSURE TO THE SUN.

Read at: http://blog.brushymountainbeefarm.com/2015/09/oxalic-acid-faqs.html

What Would Happen If Honey Bees Disappeared (Video)

 Care2    By Ashlyn Kittrell  July 15, 2015

(Video "The Death of Bees Explained: Parasites, Poisons, and Humans from Kurzgesagt and The Nova Project)

Although we don’t entirely know why, bees are disappearing. While scientists have several theories as to why this might be happening, the overarching conclusion is that widespread impact will occur as the bee population dwindles. Some theories about the disappearance of bees include parasites called varroa mites that weaken the bee by sucking fluid from their bodies. It’s hard to kill these mites without also harming the bees, making this a particularly hard problem to navigate. Bees also need plenty of food and water to survive; but with human population growth their access to clean water and plants may be limited.

There are several things we can do to help bees stick around. Supporting local beekeepers by buying their honey products is one way to make sure that they have the resources to help their hives survive. Another helpful strategy is planting blooming plants. Not only does this provide bees with the pollen they need, but it’s also great motivation to have a beautiful garden. However, when planting anything it is important to avoid insecticide dusts as well as any neonicotonoid pesticides. Both of these can get carried back to the hive.

In 1988, there were five million hives. Today, there are 2.5 million. While we aren’t entirely sure why so many colonies are collapsing, we can be sure that the loss of bees would change the world.

To see what other effects the loss of bees would have as well as what may be causing the decline, watch the video from Kurzgesagt and The Nova Project.

Read more: http://www.care2.com/greenliving/what-would-happen-if-honey-bees-disappeared-video.html#ixzz3g5FeSNlp

Tiny Parasite May Contribute to Declines in Honey Bee Colonies by Infecting Larvae

UC San Diego News Center   By Kim McDonald May 27, 2015

Biologists at UC San Diego have discovered that a tiny single-celled parasite may have a greater-than expected impact on honey bee colonies, which have been undergoing mysterious declines worldwide for the past decade.

In this week’s issue of the journal PLOS ONE, the scientists report that a microsporidian called Nosema ceranae, which has been known to infect adult Asiatic and European honey bees, can also infect honeybee larvae. They also discovered that honey bee larvae...

Read more... http://ucsdnews.ucsd.edu/pressrelease/tiny_parasite_may_contribute_to_declines_in_honey_bee_colonies_by_infecting

Oxalic Acid Registration Comments Wanted by EPA

BEE CULTURE: CATCH THE BUZZ         February 5, 2015

 By Alan Harman

   There’s great news for beekeepers with the U.S. Department of Agriculture seeking approval for the in-hive use of oxalic acid dihydrate to control Varroa mites.
   It’s a treatment long used in Europe that kills up to 97% of mites in a hive,
   The government’s Federal Register lists an application for Environmental Protection Agency approval for the product, long successfully used in Europe in the colony against Varroa.
   The notice is signed by Robert NcNally, director of the Biopesticides and Pollution Prevention Division of the Office of Pesticide Programs.
    A spokeswoman at the EPA’s Office of Pesticide Programs confirmed receipt of the USDA application.
   Approval of the application would give U.S. beekeepers a new weapon in their fight against Varroa.
  European beekeepers say they successfully use vaporized oxalic acid, or a 3.2% solution of oxalic acid in sugar syrup, as a miticide against Varroa.
   It can be used in both the liquid form and as crystals that can be evaporated by electric heater pans.
   Oxalic acid had been successfully used by beekeepers in the United Kingdom for several decades to kill Varroa when Sussex University conducted a study to determine the effectiveness of different doses and application methods of oxalic acid on mite and bee mortality.
   The experiment involved 110 hives comparing three application methods and three different doses that was completed in 2014. Hives were treated in early January 2013 when they had no brood.
   Oxalic acid does not kill Varroa in sealed cells, but rather kills mites carried on the bodies of workers and also those crawling in cells not yet capped.
   The researchers determined the proportion of mites killed by washing the mites off a sample of about 300 workers bees immediately before and after 10 days of treatment with oxalic acid.
   They also determined the number of bees killed at the time of treatment, together with hive mortality and strength four months later in spring.
   The university says the results came to a clear and encouraging conclusion. Application of oxalic acid via sublimation, where it is applied in its pure form by vaporizing the crystals with a special heated tool, was superior to application as a solution via either spraying or dribbling.
   Sublimation gave a greater kill of Varroa at a lower oxalic acid level and showed no increase in bee mortality. In fact, four months after treatment, the hives treated via the sublimation had more brood than the 10 untreated colonies.
   The sublimation method is quick and easy, as the hives do not need to be opened.
   To confirm the results, the sublimation technique was retested a year later in broodless honey bee colonies.
   “An amazing 97% of the Varroa were killed by using 2.25 grams of oxalic acid per hive, and colony survival three months later in spring was close to 100%,” the university says.
   It says beekeepers only need to carry out this treatment once a year because it reduced the number of mites so dramatically it takes them a long time to build back up again.
   The Federal Register notice says the application potentially affects those involved in crop and animal production, food manufacturing and pesticide production.
   Comments must be received by the EPA on or before March 6.
   Oxalic acid dihydrate is a colorless, odorless, crystalline solid. It is potentially fatal if swallowed or inhaled. It can also cause discoloration, irritation and burns of the skin as well as permanent damage to the eyes.
   One operating manual says all employees who handle this material should be trained to handle it safely.
   “Areas in which this compound is used should be wiped down periodically so that this substance is not allowed to accumulate,” it says.
    In Canada, the British Columbia Ministry of Agriculture says oxalic acid dihydrate should only be applied in late fall when the colony has no brood. Any open brood in the colony is likely to be killed by oxalic acid.
   “Even though the product is not as volatile as formic acid, always wear rubber gloves and safety glasses when handling the product,” it says “Avoid inhalation of vapors.”
   The ministry says it should be applied only once.
   “Oxalic acid can be applied at cool temperatures, either through vaporization (crystals heated and converted directly into a gas vapor) or trickling an acid-sugar syrup solution onto the bees.
   One European expert goes even further.
   “It cannot be stressed too strongly that oxalic acid is an aggressive substance and needs to be treated with respect,” he says. “Acid resistant gloves and goggles should be worn and an apron of the type used by mortuary attendants, along with wellington boots that have the tops covered by gaiters so that any falling liquid cannot fall into the boot.
   “A respirator that has specialized organic acid filtering will be required in cases where the acid is sprayed or vaporized.”
   The EPA is also seeking comment on an application from Certis USA L.L.C. to market a product called BmJ WG with a fungicide that claims to reduce plant viral infections and Bacillus mycoides isolate. It is intended for use on almonds, citrus, cole crops, cucurbits, fruiting vegetables, grapes, legumes, lettuce, pecans, pome fruits, potatoes, spinach, and sugar.

Check Out Whats New At www.BeeCulture.com

..

November Bee Lab Varroa and Nosema Results

Bee Informed Partnership   By Rachel Bozarth          December 4, 2014

Although the official start of winter does not begin for a few weeks, bitter cold air has spread across much of the northern region. The Minnesota and Oregon Tech Teams finished up their sampling at the end of October, so the honey bee samples received this month were all from the California team (where they are experiencing 60-70°F weather).

We examined 220 California samples for Varroa and 236 for Nosema. The average value for Varroawas 0.71 mites per 100 bees, and the average value for Nosema was 0.30 millions of spores per bee. Remarkably, these averages are almost exactly the same as the averages for California last month. However, our current disease levels are much lower than they were last year in November 2013.

Graph 1: A comparison of Varroa averages in November 2013 and 2014.Graph 2: A comparison of Nosema averages in November 2013 and 2014.


Graph 1: A comparison of Varroa averages in November 2013 and 2014.

Graph 2: A comparison of Nosema averages in November 2013 and 2014.

Bee Informed Partnership

A Warming World May Spell Bad News for Honey Bees

The following is brought to us by ABJ Extra    November 26, 2014

Researchers have found that the spread of an exotic honey bee parasite, Nosema ceranae, -now found worldwide - is linked not only to its superior competitive ability, but also to climate, according to a new study published in the journal Proceedings of the Royal Society B.

The team of researchers, including Myrsini Natsopoulou from the Martin-Luther-Universität Halle-Wittenberg, who co-led the research alongside Dr. Dino McMahon from Queen's University Belfast, believes that the parasite could become more prevalent in the UK in the future and their findings demonstrate the importance of both parasite competition and climate change in the spread of this emerging disease.

Myrsini Natsopoulou said: "Our results reveal not only that the exotic parasite is a better competitor than its original close relative, but that its widespread distribution and patterns of prevalence in nature depend on climatic conditions too".

The research compared pathogen growth in honey bees that were infected with both the exotic parasite, Nosema ceranae and its original native relative, Nosema apis.

Experiments showed that, while both parasites inhibit each other's growth, the exotic Nosema ceranae has a much greater negative impact on the native Nosema apis than vice versa. By integrating the effects of competition and climate into a simple mathematical model, the researchers were better able to predict the relative occurrence of both parasite species in nature:Nosema ceranae is common in Southern Europe but rare in Northern Europe.

Coauthor of the study, Prof. Robert Paxton of Queen's University Belfast, added: "This emerging parasite is more susceptible to cold than its original close relative, possibly reflecting its presumed origin in east Asia. In the face of rising global temperatures, our findings suggest that it will increase in prevalence and potentially lead to increased honey bee colony losses in Britain."

Read at... http://us1.campaign-archive2.com/?u=5fd2b1aa990e63193af2a573d&id=bed629ab1c&e=df8d36cef5

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Can Stress Management Help Save Honey Bees?

         November 24, 2014

 

Honey bees foraging on sunflower. Honey bee populations are clearly under stress--from the parasitic Varroa mite, insecticides, and a host of other factors--but it's been difficult to pinpoint any one of them as the root cause of devastating and unprecedented losses in honey bee hives. Researchers writing in the Cell Press journal Trends in Parasitology on November 24th say that the problem likely stems from a complex and poorly understood interplay of stresses and their impact on bee immunity and health. It's a situation they suspect might be improved through stress management and better honey bee nutrition.

As the bees have grown weaker with stress, they are left susceptible to diseases that the beneficial insects can normally carry without issue. That's especially problematic given that honey bees live together in such close quarters.

Honey bees live in complex societies, characterized by densely packed populations, and have evolved unique mechanisms for interacting with pathogens, explained Francesco Nazzi and Francesco Pennacchio of the Italian universities of Udine and Napoli, respectively. Some pathogens, such as the deformed wing virus, can cause asymptomatic infections that are normally kept under control by the immune system.

"These covert infections are very common all over the world and represent a kind of Damocle's sword for honey bee colonies," Nazzi said. "When bees are exposed to stress agents, which may adversely affect the immune competence, a sudden health decay can occur due to uncontrolled pathogen proliferation."

The first records of mysterious deaths of honey bee colonies were reported in the United States in 2006, followed shortly by similar reports in other countries. Systematic monitoring in Europe and the United States has shown that losses in the range of 20 to 30 percent of hives are common, and, in some places, the situation has been much worse.

The Varroa mite certainly doesn't help matters, as it sucks hemolymph (the equivalent of blood) from the insects' bodies, debilitating the bees and facilitating viral transmission. Neurotoxic insecticides like neonicotinoids, at sublethal doses, may also impair the bees' immune response and contribute to colony decline and eventual losses.

"But," Nazzi and Pennacchio say, "their importance depends on the health conditions of exposed bee populations and cannot be considered the sole factor responsible for colony losses. Looking at bee colony losses from this perspective may allow us to partly explain the multifactorial origin of this multifaceted event."

They call for more basic science to produce sound knowledge of the underlying immune responses and the molecular mechanisms that drive them. Those should be followed by tests under natural, field conditions, along with efforts to select for natural bee populations that are more resistant to those stresses. New schemes of "Integrated Stress Management" are also needed.

Honey bees might be fortified not only by helping to manage their obvious stresses--by keeping parasites in check, for example--but also by paying more attention to their diet, the researchers say.

"Beekeepers should pay extreme attention to parasite control, not only by acting directly on them, but also by enhancing the bee competence to face the challenge of environmental stress that may negatively influence immunity and health conditions," researchers said, drawing special attention to breeding for resistance and supplementary nutrition in the form of sugars, pollen, and other food sources.

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October Bee Lab Varroa and Nosema Results

Bee Informed Partnership   November 10, 2014

The Maryland lab has been very busy this past month! We temporarily relocated our sample processing while our lab undergoes a remodel. This remodel will permit us to process a larger number of samples.

For the month of October (10/2-10/29/14), numerous samples were processed in the Maryland Bee lab.  The lab examined 1448 varroa and 1327 nosema samples overall. This resulted in an increase of 600 (71%) varroa and 540 (69%) nosema samples over the previous month. September 2013 was our busiest month last year, but October 2014 has surpassed that.

The average value for nosema spores for California...

Read more...

The Head-Scratching Case of the Vanishing Bees

 The New York Times  By Clyde Haberman  September 28, 2014

The mystery of Colony Collapse Disorder has brought honeybees into the public eye.
But the story of their plight — and its impact — is more complicated.  
Video by RetroReport on Publish DateSeptember 28, 2014.

In 1872, a merchant ship called the Mary Celeste set sail from New York, and four weeks later was found by sailors aboard another vessel to be moving erratically in the Atlantic Ocean 400 miles east of the Azores. Curious, those sailors boarded the Mary Celeste, only to find nary a soul. The cargo was intact, as were supplies of food and water. But there was no sign of the seven-man crew, the captain, or his wife and daughter, who had gone along for the journey. To this day, what turned that brigantine into a ghost ship remains a maritime mystery.

It was with a nod to this history that when bees suddenly and mysteriously began disappearing en masse in Britain several years ago, the phenomenon came to be known there as Mary Celeste Syndrome. Beekeepers in this country were similarly plagued. Honeybees, those versatile workhorses of pollination, were vanishing by the millions. They would leave their hives in search of nectar and pollen, and somehow never find their way home. On this side of the Atlantic, though, the flight of the bees was given a more prosaic name: colony collapse disorder.

What caused it remains as much of a head-scratcher as the fate of the Mary Celeste, but the serious consequences for American agriculture were clear. And thus it draws the attention of this week’s Retro Report, part of a series of video documentaries examining major news stories from the past and analyzing what has happened since.

The centrality of bees to our collective well-being is hard to overstate. They pollinate dozens of crops: apples, blueberries, avocados, soybeans, strawberries, you name it. Without honeybees, almond production in California would all but disappear. The United States Department of Agriculture estimates that nearly one-third of everything that Americans eat depends on bee pollination. Billions of dollars are at stake each year for farmers, ranchers and, of course, beekeepers.

But in the fall and winter of 2006-07, something strange happened. As Dave Hackenberg, a beekeeper in central Pennsylvania and in Florida, recalled for Retro Report, he went to his 400 hives one morning and found most of them empty. Queen bees remained, but worker bees had vanished.

Mr. Hackenberg’s distress resounded in apiaries across the country. Some of them lost up to 90 percent of their colonies. Not that mass bee disappearances were entirely new. They had occurred from time to time for well over a century. But as best as could be told, no previous collapse matched this one in magnitude. It became a national sensation, down to predictable references in television news reports to, yes, the latest “buzz.”

Less predictable was how to explain the catastrophe. Theories abounded. Some suggested that cellphone towers had disoriented the bees. Others said the fault lay with genetically modified crops. More likely, entomologists said, a pathogen might be to blame. Yet other experts pointed damning fingers at pesticides, notably a group known as neonicotinoids, which chemically resemble nicotine. Neonics, as they are known for short, are “systemic” chemicals, meaning that they circulate throughout a plant and reach its leaves or flowers, where bees do their work. One underlying premise is that the pesticides cloud the bees’ brains, leaving them in a haze and short-circuiting their sense of how to return home.

 

A highly probable villain, some scientists say, is a parasitic mite with the singularly unsavory name of Varroa destructor. It burrows into a bee and compromises its immune system. Jeffery S. Pettis, an Agriculture Department entomologist, said in testimony before a House subcommittee in April that “Varroa destructor is a modern honeybee plague.” There is, too, a possibility that honeybees are simply overworked. From season to season, colonies are routinely trucked around the country to pollinate crops. It just may be, some specialists in this field say, that the bees are like many modern workers: They are stressed, and get tuckered out.

With so many theories in play, several federal agencies weighed in last year, with a joint study that effectively checked the “all of the above” box. A mélange of the various factors was behind the colonies’ devastation, the agencies’ report said, putting no more weight on one cause than on any other.

While Mary Celeste Syndrome — it sounds more lyrical than colony collapse disorder, does it not? — caught everyone’s attention, it is not at the core of concerns over bees today. Colonies still die, for a variety of reasons, but there have been fewer instances of the mass collapse that caused so much anguish in 2006 and ’07. Beekeepers have replaced their dead hives. Experts interviewed by Retro Report seemed unperturbed by thoughts that honeybees were about to disappear.

Rather, what worries them is a gradual, steady shrinkage of the honeybee population over the years. Two decades ago, the United States had more than three million colonies; now it is down to an estimated 2.4 million, the Agriculture Department says. And more bees seem to be dying — from all causes, not just colony collapse — in the normal course of what are referred to as the “winter loss” and the “fall dwindle.” Where annual bee losses were once in the range of 5 percent to 10 percent, they are now more on the order of 30 percent. The fear is that this dying-off is too great for the country’s ever-expanding agricultural needs. That, specialists like Dr. Pettis say, is what would really sting.

Read and view comments at: http://www.nytimes.com/2014/09/29/us/the-head-scratching-case-of-the-vanishing-bees.html?smid=tw-share#story-continues-5

________
The video with this article is part of a documentary series presented by The New York Times. The video project was started with a grant from Christopher Buck. Retro Report has a staff of 13 journalists and 10 contributors led by Kyra Darnton. It is a nonprofit video news organization that aims to provide a thoughtful counterweight to today’s 24/7 news cycle.

Honey Bee Viruses, the Deadly Varroa Mite Associates

xtension By Philip A. Moore, Michael E. Wilson, John Skinner     August 21, 2014

Introduction

Varroa mites (Varroa spp.) are a ubiquitous parasite of honey bee (Apis spp.) colonies. They are common nearly everywhere honey bees are found, and every beekeeper should assume they have a Varroa infestation, if they are in a geographic area that has Varroa (Varroa mites are not established in Australia as of spring 2014). Varroa mites were first introduced to the western honey bee (Apis mellifera) about 70 years ago after bringing A. mellifera to the native range of the eastern honey bee (Apis cerana). Varroa mites (Varroa jacobsoni) in eastern honey bee colonies cause little damage. But after switching hosts and being dispersed across the world through natural and commercial transportation of honey bee colonies, Varroa has became a major western honey bee pest since the 1980’s. Varroa mites (Varroa destructor) are now the most serious pest of western honey bee colonies and one of the primary causes of honey bee decline (Dietemann et al. 2012). A western honey bee colony with Varroa, that is not treated to kill the pest, will likely die within one to three years (Korpela et al. 1993; Fries et al. 2006).

Varroa Life History

Varroa mites attack honey bee colonies as an external parasite of adult and developing bees, by...

Read more...  http://www.extension.org/pages/71172/honey-bee-viruses-the-deadly-varroa-mite-associates#.VA5XBfldUmm

Honeybee Homing Hampered by Parasite

Phys.org    September 3, 2014

In an experiment at Rothamsted Research institute in Hertfordshire, 35 per cent of bees infected with Nosema ceranae never made it home. Among healthy foragers, the figure was less than ten per cent.

The findings are published in the journal PLOS ONE.

'This is obviously bad news for bees infected with the parasite,' says Dr Stephan Wolf, of Rothamsted Research, who led the study. 'But in some ways it's surprising that so many infected bees did so well.'

'We're talking about heavily infested animals, but we couldn't find any difference in their flight patterns - they didn't seem to get lost or confused. It seems some of them were just too exhausted to make it back to the nest.'

'This raises important questions about why some infected bees are able to function in exactly the same way as healthy bees, while others are unable to cope.'

Managed honeybees pollinate important commercial crops throughout the world, but in recent years they have been in decline.

In a study published in January this year, scientists said many European countries are now facing honeybee shortfalls. The problem is particularly acute in Britain, where there are only enough honeybees to pollinate a quarter of crops.

Alongside the unintended consequences of pesticides targeted at other species, diseases and parasites have shouldered most of the blame.

Nosema parasite spores invade cells in the gut, drawing energy for themselves while damaging the bees' ability to absorb food.

There are two species of the parasite - Nosema apis, native to Europe, and Nosema ceranae, an Asian species which in recent years has spread rapidly throughout the world, and is now widespread throughout Europe and the UK.

Nosema ceranae can be terminal for honeybee colonies, but its symptoms are typically subtle in individual bees, giving away very few signs of infection before death.

Previous research suggested that it affects bees' ability to find their way back to the colony. To investigate what happened to them, the team attached tiny radar transponders to the backs of a mixture of clean and infected bees.

Each transponder, just 16mm long and weighing less than the average pollen load, sent a distinct signal back to the radar, allowing scientists to track the position of each bee in real time.

The bees were released onto a field at Rothamsted some distance from the colony, challenging them both to find their bearings and to make it all the way back to the hive.

Although there was very little difference between the flight characteristics of clean and infected bees, some infected  seemed to become exhausted, taking longer stops before settling on the ground and disappearing from the radar.

The only available treatment for Nosema infections, a fungicide called fumagillin, is banned in the European Union over environmental safety concerns. And there is a debate among researchers about its effectiveness against the parasites.

Scientists continue to work on developing safe and efficient alternatives.

More information: Stephan Wolf, Dino P. McMahon, Ka S. Lim, Christopher D. Pull, Suzanne J. Clark, Robert J. Paxton, Juliet L. Osborne, 'So Near and Yet So Far: Harmonic Radar Reveals Reduced Homing Ability of Nosema Infected Honeybees', 2014, PLOS ONEDOI: 10.1371/journal.pone.0103989

Read more at: http://phys.org/news/2014-09-honeybee-homing-hampered-parasite.html#jCp

This story is republished courtesy of Planet Earth online, a free, companion website to the award-winning magazine Planet Earth published and funded by the Natural Environment Research Council (NERC).