Bees/o/-Development Journal 84

BEE DEATH IN THE USA: is the honey bee in danger?Wolfgang Flitter, President of the Apimondia Standing Commission for Bee HealthInternational (DIE) and German National Reference Laboratory for Bee Diseases, CVUA, Germany

Many people are concerned about the future of the honey bee because ofthe great number of bee colony losses, particularly in the USA, asrecently highlighted throughout the media. It is of such importance thatthe US House of Representatives held a special hearing to deal with thematter, and even the New York Times and the Journal Science publishedmajor features. As often happens, this creates media exaggerationranging from 'Bee AIDS' to the extinction of mankind as a consequenceof the loss of honey bees. To address the problem correctly, all the factsare needed.

How did it start?During October-December 2006 beekeepers throughout the USAannounced a dramatic spate of sudden bee colony losses. Manybeekeepers observed for the first time that no dead bees remained either

t of, or inside the hives. They found empty hives and combs withof all ages and plenty of food and in certain cases, the queen

along with some young bees, was still strolling over the combs. TheMinistry of Agriculture immediately established a working group withinthe Agricultural Research Service (ARS) to examine initial test resultsand defined their observations as 'Colony Collapse Disorder' (CCD).

Initial surveys indicated losses in some apiaries of 30-90% but, as withall cases of this kind, it was difficult at first to get reliable data on thetotal losses. However, the extent of the problem became clearly visiblewhen facts revealed that up to 700,000 colonies had died.

Is the problem new?Similar symptoms with colony losses have already occurred in the USA:in Alabama and Minnesota in 2002 and 2004, as well as in California in2005. But losses were also recorded outside the USA: for example inAustralia and Mexico in 1975 and in those cases, this phenomenon wascalled 'disappearing syndrome'.

In Europe, too, there have always been losses of bee colonies from timeto time, showing the same symptoms. Extremely high losses wererecorded during the winter of 2002-2003, estimated at 20% in Franceand up to 38% in Sweden. In Germany, an average of 32% of the onemillion bee colonies died and many beekeepers lost everything. Thesymptoms were more or less identical with those recently observed inthe USA. In Germany this phenomenon is called Kahlfliegen. It firstoccurred in France about 15 years ago and can still be observed today:most of the colonies collapsing in harvest. Across the rest of Europesymptoms were numerous and varied, and ranged from brood of allstages left in the hive, few bees left in the hive until food stocks ran out,or cleared by robbing bees from stronger colonies.

How do bees avert diseases?At first glance it seems strange that bees depart from their colony,leaving brood and food behind. To understand this you have to study thebee colony's procedures for averting diseases. All actions of the single

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a - *T!HHHm&2aBtet£!Sga&a&Only 14 days ago, strong bee colonies were crowded on these brood combs at an apiary in the USA afflicted by CCD. Now mainly young bees are left.

Bees/orDevelopment Journal 84 BEE DEATH IN THE USA

bee concentrate on one single aim: to guarantee survival andmultiplication of the colony. The loss of one single bee does not matter.The colony's health is above its own, even if this means the single bee'sdeath. The colony's defence strategy against diseases therefore givesmore priority to social behaviour than to the single bee's own immunesystem. Recognising and removing ill brood is part of the defencemechanism of a honey bee's make-up, and the removal of ill or infestedbees is also important. This is achieved by preventing ill or otherwise'strange' bees from entering the hive, or they do not return from foraging.Foraging and not returning to the colony, especially of old bees, istherefore part of the natural hygienic behaviour of the bees. It happens ahundred or a thousand times each day. A dramatic situation occurs only ifthe colony is not able to regenerate sufficiently, or if all of the bees departwithin a few days. If a colony of African bees is severely infested by theSmall hive beetle Aethina tumida, the process of departure happens in aco-ordinated way with all the bees leaving as if in a swarm. However, acolony of European Apis mel/ifera bees, for example with a seriousVarroa destructor infestation, may react in a more disorganised way. In aKarma-infested colony, infested bees leave the hive and invade othercolonies in the nearby environment. This leads to an explosivelyincreasing number of mites, and rapid colony destruction: this isimmediately observed by a vigilant beekeeper. Collapsing coloniesdistribute thousands of mites to neighbouring colonies. You sometimesfind within one week over 2,000 new mites in already treated colonies.They must have arrived via robbing bees or not returning bees.

What is the reason?Empty hives, without reason, can complicate the issue as to why the beesleft. Only if some bees or brood remain can one try to discover why. Inspring, if you have heavy colony losses, in most cases Nosema sporescan be found. For several years our examinations have shown thatNosema ceranae, which might have migrated from Asia, has been found.However, it also appears in surviving colonies, and very frequently,remaining bees are infected by the viruses transmitted by Varroa mites.The brood can also show additional infections with fungi and bacteria. Itis still to be answered if the diseases diagnosed are the result of thereduced bee population and increasing stress in the remaining colony, orif they are actually responsible for the colony loss. Even if Varroa mitescannot be found in all brood cells, it has been assumed in Europe thatthis parasite is the cause. It weakens colonies to the extent that theybecome increasingly susceptible to other diseases and unfavourableliving conditions. The latter is difficult to investigate and to quantify. Thisleaves room for all kinds of speculation, ranging from the utilisation ofspecific pesticides, to genetically modified plants (GMOs), to radiationfrom mobile telephone masts. This list may be extended as long as youlike.Similar discussions are now underway in the USA. American colleaguespoint out that the symptoms appear in regions without any access tomobile telephone networks, and where no GMO crops have beencultivated. In the USA, until now, Deformed Wing Virus could nearlyalways be found in the remaining bees examined. This corresponds toour examinations in more than 300 apiaries in Austria, Germany andSwitzerland, after winter losses in 2002-2003, when we nearly alwaysfound this virus. Recent examinations in co-operation with other Europeancolleagues show that this virus, contrary to other bee viruses, only rarelyshows genetic variations all over the world, and is therefore closelyconnected with the spread of the Varroa mite. For this reason it can beassumed that the Varroa mite represents one of the main reasons for thebee losses, and this includes the USA.Certainly, the reasons are multi-factorial and regionally different. Ofcourse, the human factor should not be neglected, influencing beecolonies not only by the way of colony management and disease control,but also by environmental conditions.

The difference between beekeeping in the USA and EuropeIn the USA (and contrary to Europe), nearly all kinds of pathogenic agentsplay a role in bee health and can be found in many colonies. Themanaged application of medicines enables beekeepers to obtain goodhoney harvests. However, even the slightest interference overturns thissystem. This became obvious when, in the 1980s, the tracheal miteAcarapis woodi and later the Varroa mite Varroa destructor, and in thiscentury the Small hive beetle Aethina tumida, were introduced.As a rule, beekeeping in the USA is focussed on maximum honey yield orpollination capacity. This means that in extreme cases, according to theprinciple of 'hire and fire', bees are kept only for a short time undermaximum exploitation, to be disposed of afterwards for financial reasons.Bee colonies that are kept throughout the year are also exposed toenormous stress because of extremely long migrations, artificial provisionwith cheap food, and colony management following strict time frames.Moreover, the bees are living in agricultural monocultures that greatlyreduce the natural diversity of the bees' diet. We know that pollenprovides honey bee colonies with natural antagonists of bacteria, fungi orwith antibiotic substances. But not every kind of pollen is equallysuitable. If there is a lack of diversity, defence facilities decrease and thecolonies become more susceptible to diseases.In industrial agriculture we use industrial beekeeping. Pollination is an ̂especially clear example. The agricultural monocultures require intense^application of pesticides. As a consequence the pieces of cropped landreaching to the horizon are often deprived of natural pollinators such asflies and beetles. And this in a continent not formerly populated bypollinating honey bees: it was the settlers from Europe who introducedthe Apis mellifera honey bee to the USA.This requires the pollination capacities of bee colonies to be directed byhumans according to strict time frames. The beekeeper profits from thefinancial value of this service: typically US$125 (€90) and more are paidper colony. So a beekeeper who is being paid for pollination services, canafford the disadvantage that the honey gathered, often polluted bypesticides, cannot be used as a food item. If the unique pollinator islacking, then agricultural output will suffer, and the total damage may behuge. In the USA, the losses due to the reduced harvest of almonds andfruits are estimated at several millions of US dollars. That is why theoutcry about losses comes not only from beekeepers, but even more fromfruit-growing farmers.

What is being done?The search for answers to this problem started years ago but up tono satisfactory results have been achieved. It is of major importance thaicolony examinations are made before CCD sets in. Only when it is knownhow the development, the progress of diseases, and the environment of acollapsing bee colony differ from a healthy one, is there is a chance tounderstand the reasons.Three years ago in Germany, the Federal Ministry of Agriculture andConsumer Protection initiated a monitoring project throughout the year inwhich bee institutes screened a total of 7,000 colonies belonging to 123beekeepers from all over the country, by taking samples and carrying outregular examinations. Similar actions are planned in other Europeancountries. To co-ordinate the approach and to exchange the results asrapidly as possible a European working group was formed. This networkis now enlarged to other countries including the USA. By means of thisco-operative effort it should be possible to solve this worldwide problemfor honey bees and beekeepers.

FURTHER INFORMATIONBID Website Information Centre: Bees and the Environment atwww.beesfordevelopment.org/info/info/index.shtmlSilent spring in northern Europe. Bees for Development Journal 71More si lent spring (Letters). Bees for Development Journal 72Dr Ritter's website (in German) www.beepathology.com