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Bee death in the USA: Is the Honeybee in danger?
For pollination, honeybees are in great demand throughout the world. Many people are worried and concerned about the future of the honeybee and this is due to the great number of bee colony losses, particularly in the USA. The issue is highlighted on a regular basis in Newspapers, TV and Radio. It is of such importance that the US House of Representatives held a special hearing to deal with the matter and such well-known newspapers like the “New York Times” and the “Science” journal write major features about it. As often happens, this creates media exaggerations ranging from “Bee AIDS” to the extinction of mankind as a consequence of the loss of honeybees. One must be aware of the coherences of all the facts to be in a position to address the problem correctly.
How did it start?
In October/December 2006 the beekeepers in the USA announced a dramatic spate of sudden bee colony losses throughout the country. Many beekeepers observed for the first time, that no dead bees remained either in front of or inside the hives. They found empty hives and combs with brood of all ages and plenty of food and in certain cases, the queen along with some young bees, was still strolling over the combs. The Ministry of Agriculture immediately established a working group within the Agricultural Research Service (ARS) to examine initial results of tests carried out and defined their observations as CCD “colony collapse disorder”.
First surveys indicated losses in some apiaries of between 30 and 90% but as with cases of this kind, it was difficult at first to get reliable data on the total losses. It really only became clear when facts stating that up to 700,000 colonies had died out and this made the extent of the problem visible.
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 in 2005. But losses were also recorded outside the USA: for example in Australia and Mexico in 1975 and in those cases this phenomenon was called “disappearing syndrome”.
In Europe, too, there have always been losses of bee colonies from time to time showing the same symptoms. Extremely high losses were recorded during the winter 2002/2003. They were estimated at 20% in France and up to 38% in Sweden. In Germany, an average of 32% of the one million bee colonies died and many beekeepers lost everything. The symptoms were more or less identical with those actually observed in the USA. In Germany this phenomenon is called “Kahlfliegen”.
It first occurred in France about 15 years ago and can be observed until today, most of the colonies collapsing in harvest. Across the rest of Europe these were numerous and varied and they ranged from brood at all stages, few bees left in the hive until food stocks ran out or cleared by robbing bees from stronger colonies.
Already more than 10 years ago, Colony Collapse Disorder („Kahlfliegen“)
could be stated in Southern Germany.
(Photo Ritter)
How do bees avert diseases?
The fact that bees would depart their colony, leaving brood and food seems strange at a first glance. To understand this you have to study the procedures of averting diseases in a bee colony. All actions of the single bee concentrate on one single aim: to guarantee survival and multiplication of the colony. The loss of one single bee doesn’t matter. The colony’s health is above its own even, if this means it’s death. The colony’s defence strategy against diseases therefore gives more priority to social behaviour than to the body’s own immune system of a single bee. Recognising and removing ill brood is part of the defence mechanism of a honeybee’s make-up and the removal of ill or infested bees plays an important role also. Either those “strange” bees are prevented from entering at the entrance or they don’t come back from foraging. Foraging and not coming back, especially of old bees, is therefore part of the natural hygienic behaviour of the bees. It happens a hundred if not a thousand times per day. A dramatic situation only occurs if the colony is not able to regenerate sufficiently or the bees depart within a few days. Whereas in case of African bees, e.g. if severely infested by the Small Hive Beetle, Aethina tumida, the process of departure happens in a quite coordinated way in form of a swarm. European bees, e.g. with a serious Varroa destructor infestation, may react in a more disorganised way. Bees infested by mites invade colonies in the environment leading to an explosively increasing number of mites in that colony, leading to a quicker destruction of the colony and this is immediately observed by a vigilant beekeeper.
What is the reason?
Empty hives, without reason, can complicate the issue as to why they left. Only if some bees or brood remain, as it is often recognised, can one try to find out the reasons. In spring, if you have heavy losses, Nosema spores can be found in most of the cases. Our examinations have shown for several years that Nosema ceranae, which has migrated from Asia, has been found. However, it also appears in surviving colonies and very frequently, the remaining bees are infected by viruses often transmitted by Varroa mites. The brood can also show additional infections with fungi and bacteria. It is still to be answered if the diseases diagnosed are the result of the reduced bee population and increasing stress in the remaining colony or if they are really responsible for the loss respectively. Even if Varroa mites cannot be found in all brood cells, it has been assumed in Europe that this parasite is the very reason. It weakens the colonies to an extent that they get more and more susceptive to other diseases and unfavourable living conditions. The latter is difficult to investigate and to measure in figures. This leaves room for all kinds of speculations. They range from the utilisation of specific pesticides to genetically modified plants (GMO) until the radiation from mobile telephone masts. This list could be extended as long as you like.
At the moment, there are similar discussions in the USA. But American colleagues point out that those symptoms also appear in regions without any access to the mobile telephone net and where no genetically modified plants have been cultivated. In the remaining bees examined until now in the USA, the Deformed Wing Virus (DW) could nearly always be found. This corresponds to our examinations of the winter losses in 2002/2003. Here we nearly always found this virus in more than 300 apiaries in Germany, Austria and Switzerland. Recent examinations made together with other European colleagues show that this virus, contrary to other bee viruses, only rarely shows genetic variations all over the world and is therefore obviously very closely connected to the spreading of the Varroa mite. For this reason it can be assumed that the Varroa mite represents one of the main reasons for the bee losses and this includes the USA.
Certainly, the reasons are manifold (multi-factorial) and regionally different. Of course, the human factor should not be neglected influencing bee colonies not only by the way of colony management and disease control but also by environmental conditions.
What’s the difference between beekeeping in the USA and in Europe?
Contrary to Europe, nearly all kinds of pathogen agents play a role in bee health and can be found in many colonies in the USA. The managed application of medicaments facilitates the ordinary beekeeper leading to a good honey harvest. Even the slightest interference overturns this system. This became obvious when, in the eighties, the Trachea mite Acarapis woodi and later the Varroa mite Varroa destructor, and in this century the Small Hive Beetle Aethina tumida was introduced.
As a rule, beekeeping in the USA is oriented to a maximum of honey yield or pollination capacity. This means in extreme cases that, according to the principle “hire and fire”, bees are only kept for a short time under maximal exploitation to be disposed of afterwards for financial reasons. But also the bee colonies kept throughout the year are exposed to enormous stress because of extremely long migrations, artificial provision with cheap food and a colony management following strict time frames. Moreover, the bees are living in agricultural monocultures reducing strongly the natural diversity of the bees’ diet. We know that pollen supplies the colonies with natural antagonists of bacteria, fungi or with antibiotic substances. But not every kind of pollen is equally suitable. If there is a lack of diversity, defence facilities decrease and the colonies get more susceptible to diseases.
In industrial agriculture there is an industrial beekeeping. Pollination is an especially clear example. The agricultural monocultures require a more and more intense application of pesticides. As a consequence the pieces of cropped land reaching to the horizon are often deprived of natural pollinators like e.g. flies and beetles. And this in a continent not formerly populated by pollinating honeybees. It is recorded that it was the settlers from Europe who introduced the honeybee to the US.
This requires the pollination capacities of bee colonies directed by humans according to strict time frames. The beekeeper profits of the financial value of this service: 125 US$ and more are paid per colony today. So the beekeeper that is getting paid for pollination, can easily get over the disadvantage that the honey gathered, often polluted by pesticides, cannot be used as food item. When the only pollinator is lacking the agricultural outputs are also lacking. The total damage is huge. In the USA, the losses due to the reduced harvest of almonds and fruits alone are estimated at several millions of US dollars. That is why the outcry about losses not only comes from beekeepers but even more from fruit-growing farmers.
What is done?
Neither in the USA nor in Europe are the bees and the beekeepers left alone with their fate. The search for answers to this problem started years ago but up to now no satisfactory results have been achieved. It is of major importance that examinations are made before Colony Collapse Disorder sets in. Only when it is known how the development, the progress of diseases and the environment of a collapsing bee colony differ from a healthy one, is there is a chance to find out the reasons.
Three years ago in Germany, the Federal Ministry of Agriculture and Consumer Protection initiated a monitoring project throughout the year in which bee institutes screened a total number of 7000 colonies belonging to 123 beekeepers from all over the country, by taking samples and carrying out regular examinations. Similar actions are planned in other European countries. To coordinate the approach and to exchange he results as rapidly as possible a European working group was formed. At present, this network is enlarged to non-European countries like the USA. By means of this common effort it should be possible to solve this worldwide existing problem of honeybees and beekeepers in the near future.
Dr. Wolfgang Ritter
Apimondia Standing Commission for Beehealth
International (OIE) and German National Reference Laboratory for Bee Diseases
at CVUA Freiburg
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