Concerted effort needed to save the honey bee
Perhaps the most accurate thing about Albert Einstein’s pronouncement on the importance of bees – “if the bee disappeared off the surface of the globe, then man would have only four years of life left.” – is that he never said it.
It’s an aphorism often quoted in the many media reports on honey bee losses, along with apocalyptic headlines warning of economic and ecological disaster if the honey bee disappears for good.
The honey bee is both a native British insect and a vital part of our agriculture and food chain. It is certainly true that honey bee colonies are dying across the world – and their complete demise would have devastating consequences for all flowering plants and the production of food (honey bees pollinate many food crops). There is a worrying downward trend in hive numbers in Britain, down from one million a century ago to 250,000 today, with similar declines in the USA. In addition, there have been many reports of large numbers of hives dying in various parts of the world. But as yet there is no agreement on a definitive cause of this phenomenon.
What does scientific research really make of these recent losses of honey bee colonies?
Professor of Apiculture Francis Ratnieks and his team at the University of Sussex Laboratory of Apiculture and Social Insects (LASI) are currently working on the Sussex Plan – a five-year programme of bee biology research, applied research into honey bee breeding and disease management and outreach to beekeepers, schools and local communities. The aim is to help the honey bee: research has already begun into breeding more hygienic bees and determining where bees forage.
Here, Professor Ratnieks and research colleague Norman Carreck, a leading authority on apiculture and bee science, provide an overview of the latest thinking, and stress the need for a “joined-up” strategy to save the honey bee from further decline.
Honey bees are being killed off by something called Colony Collapse Disorder, aren’t they?
It’s not helpful to describe all honey bee decline as “Colony Collapse Disorder”. The term CCD was coined to describe a specific set of symptoms in USA bee hives. Commercially reared honey bees are responsible for pollinating huge numbers of crops in the USA, where the California almond crop, pollinated by one million bee colonies specially shipped in for the job, is worth £2 billion alone. To this day, no one knows what the cause of CCD is, although a combination of pathogens is the most likely cause.
So CCD is just a part of the problem?
Yes. The challenge is that there seems to be no unifying cause to colony collapse globally, but interaction between multiple factors, such as weather patterns, availability of forage (the flowers bees need for nectar and pollen), quality of forage, pesticides, pests and diseases. More research needs to be done into all of these contributing factors – far more than is being undertaken currently.
Pesticides are a likely cause of bee death, surely – in trying to poison the “bad” pests that eat our crops, we also kill helpful insects such as bees?
A group of pesticides called neonicatinoids have been blamed for extensive colony collapse. These chemicals were banned in France, but colony losses have continued there. So it is unlikely that these chemicals themselves are causing colony collapse. Rather than killing bees outright, however, pesticides might be working against honey bees in subtler ways, by making them more susceptible to disease. Herbicides don’t directly kill honey bees, but they are part of modern intensive agriculture which has resulted in reduced numbers of flowers in the countryside. Bees get their food – pollen and nectar – from flowers.
A lot of attention has been given to various possible causes, ranging from mobile phone microwaves and the development of GM crops, but none of these suggestions offers a credible explanation for honey bee colony losses.
Could we be looking at a new disease, then?
It’s unlikely that we are looking for a micro-organism not already known to scientists. In December comprehensive surveys of honey bee losses were carried out in 16 countries in North America and Europe. A definitive explanation for these losses is still elusive, but the belief is that the interaction between existing pests and pathogens are still the most important cause of colony collapse.
A mite called Varroa destructor, a parasite originally confined to the Asian honey bee Apis cerana, has now colonised “our” honey bee, Apis mellifera, and is now found on Apis mellifera in all continents except Australia. Varroa destructor can transmit a variety of honey bee viruses. The incidence and abundance of viral infections in the honey bee has increased substantially since this mite colonised the honey bee, but it cannot alone account for all colony collapse. A recent study showed that viruses can spread from bee to bee, without the need for the mite to be present, and indeed cirus epidemics occurred before Varroa mites were present on Apis mellifera.
A 2007 study carried out in the USA showed that Israeli acute paralysis virus was the pathogen most commonly associated with CCD, but a 2009 study from the USA that investigated 60 factors that might be associated with colony losses gave a much less clear picture. Just how important this this and other viruses are in causing CCD will need further research.
Are there any other suspects?
Another pathogen is a gut parasite, Nosema ceranae, which has recently been found in bee hives around the world. Like Varroa destructor, Nosema ceranae originated in the Asian bee, Apis cerana, and seems to be replacing the type of Nosema, N. apis, normally found in our species of honey bee, Apis mellifera. However, there is good evidence that Nosema ceranae colonised the USA honey bee before CCD took hold. Once again, more research is needed to determine how virulent Nosema ceranae really is. Researchers in Spain are convinced it is causing colony deaths in their country, but it seems not to be causing a problem in several other countries where it has been monitored.
So we’re none the wiser then?
Actually we are. We now know that we are dealing with a complex puzzle, and that there is no single or novel cause, and that the situation is not the same in every country. The first annual report of the U.S. Colony Collapse Disorder Steering Committee in July 2009 supports this idea. Conventional causes of bee death, in complex and varied combinations, could be to blame – for example, the interaction between known pests and pathogens (complex and widespread), poor weather conditions that impact on foraging, lack of forage and management factors such as use of pesticides and long-distance transport of hives to nectar sources or pollination locations.
Many scientists across the world are now investigating the possible causes of honey bee death. Comprehensive collaboration would help to fit the pieces of this complicated jigsaw together. There also needs to be closer collaboration between science and beekeeping. The formation of COLOSS, an EU-funded network which coordinates all national bee research activity across Europe, and now globally, aims to explain and prevent massive honey bee colony losses. So far it has 160 members drawn from 40 countries worldwide. COLOSS will seek to promote consistent research approaches and a transnational research programme that will be of benefit to science and beekeeping practice.
Good hive management remains a key weapon in the fight against colony collapse. Beekeeping is becoming increasingly technical (pollen substitutes are now given to bees, for example, in place of the real thing foraged from flowers), which may have unintended consequences for bee health. Further research is needed in this area, too, to ensure that colonies are kept healthy.
For example, at the University of Sussex we have started a project to breed hygienic bees that are more effective at removing diseased brood from the hive, thereby helping beekeepers to maintain hives free of debilitating pests and disease. Another project is examining where honey bees collect nectar and pollen so that we can better understand how bee-friendly the modern landscape is. These two projects will provide information and resources that can help beekeepers keep their colonies healthy, and help improve the food supply for bees and other pollinating insects. Food supply is vital: even if we could somehow control all honey bee diseases, the bees still have to find food (flowers).
So we could be on the verge of solving the riddle of this modern threat to our long relationship with the honey bee?
The problem facing honey bees can be thought of as a wake-up call to action and to take the need for pollination more seriously. There are reports from hundreds of years ago of large numbers of honey bee colonies dying, and it is unlikely that there will ever be an end to the need for research and action to safeguard thriving populations of honey bees and beekeeping in the UK and other countries.
Notes for Editors
Notes for Editors
For a more detailed appraisal of honey bee research into colony collapse, see:
The Journal of Apicultural Research Special Issue: International Studies on Honey Bee Colony Losses, edited by Dr Peter Neumann (Chair of the COLOSS network and Norman Carreck, who is also Scientific Director of the International Bee Research Association (IBRA).
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