“You will probably more than once have seen her fluttering about the bushes, in a deserted corner of your garden, without realising that you were carelessly watching the venerable ancestor to whom we prob- ably owe most of our flowers and fruits (for it is actually estimated that more than a hundred thousand varieties of plants would disappear if the bees did not visit them), and possibly even our civilisation, for in these mysteries all things inter- twine.” ― Maurice Maeterlinck, The Life of the Bee (published 1901)
There was a time when dinosaurs roamed the earth, not worried about being stung by a bee. Then, about 100 million years ago, flowering plants and bees co-evolved together. There are about 20,000 bee species in the world including solitary, bumble, stingless, and honeybees; all of which visit flowers to collect nectar and pollen. Among these, honeybees demonstrate social traits, build large colonies, store honey, have one reproducing queen, and demonstrate distinct divisions of labour.
The honeybee has been a fascinating insect for humans because, especially for the majority of early humans, honey was the only sweetener for their diet. The earliest evidence of honey hunting is an 8,000 year old cave painting in Bicorp, Spain that shows a group of humans climbing up vines, collecting honey from a beehive.
The Western honeybee (Apis mellifera), the most widely spread honeybee and the most well known, originated in Africa but is now found in every continent except Antarctica. It was first domesticated by the Egyptians who constructed the first known beehives going back to 3,000 BCE, however, it was only in 1852, when Lorenzo Langstroth created his movable frame hive that we no longer had to kill bees to obtain honey. This also accelerated our ability to observe and study this captivating social animal. What we confirmed with these observations was nothing less than the realisation that honeybees are as sophisticated in their social behaviour as any in the animal kingdom. The famous naturalist, Charles Darwin, was also fascinated by honeybees and regarded them to be an evolutionary puzzle that could not be explained by his then-understanding of natural selection.
Lately, our interest with the honeybee is no longer just a simple fascination but a vital necessity. In fact, apart from honey and other products of benefit to us like venom, propolis and wax, we rely on honeybees to pollinate one third of all our crops including the majority of fruits and vegetables. Even the venom of the honeybee sting is employed for the treatment of arthritis and is under research for treatment of multiple sclerosis and other autoimmune diseases. Lately however, honeybee populations have shown decline in North America and Europe, challenging our bond with these social animals and also threatening our very food supply.
This is because the domestic bee plays a vitally important role in agriculture, due to its indispensable function in crop and natural plant pollination. The value of the role played by the honeybee in the pollination of flowers far exceeds the economic returns from the hive. In 2012, the value of crops pollinated by bees was estimated at $14 billion US dollars in the United States alone. The contribution of this remarkable insect is not limited to the US but is in fact worldwide. As the UN Environment Programme director, Achin Steiner pointed out in March 2011, “…the way humanity manages or mismanages its nature-based assets, including pollinators, will in part define our collective future in the 21st century. The fact is that of the 100 crop species that provide 90 per cent of the world’s food, over 70 are pollinated by bees”.
Unfortunately, the honeybee populations around the world have started to significantly decline during the last decade among those of the European breed in particular., This phenomenon of honeybee decline, known as ‘Colony Collapse Disorder’ (CCD) represents a major challenge for scientists and beekeepers, especially since its causes are still not well determined. Most recently, statistics in the US have shown that between April 2014 and 2015, 42% of honeybee colonies of beekeepers died. We should keep in mind that if the bees disappear altogether, 80% of the vegetables and fruits we enjoy eating would not be available anymore and the ability to produce food for the world’s increasing population would become nearly impossible.
It is increasingly being realised that the cause of CCD is multifaceted and multifactorial. A few main factors however, stand out as the principal drivers in the decimation of honeybee populations. It is to these, that we shall now turn our attention.
The Varroa Mite
The first factor is the old enemy of the honeybee and a very well studied parasite known as the Varroa mite. This mite spends its life on the bee’s body and continually sucks her ‘hemolymph’ – a substance that acts as blood does in humans. The Varroa mite, originally a native pest of the Eastern honeybee (Apis cerana), came into contact with the non-resistant Western honeybee (Apis mellifera) in the 1960s and spread with devastating results. Scientifically called Varroa destructor, this mite has spread to every continent except Australia, where strict controls on bee import and border checks keeps this mite out. This mite is widely distributed throughout world apiculture and can only reproduce through honeybees and thus is considered harmless to other insects.
This parasite is extremely damaging to honeybee colonies. While the mites alone may cause mortality by simply feeding off larvae and adult honeybees, they mainly kill by acting as disease carriers and by transmitting any number of viruses and bacteria to the bees. It cripples adults and kills potential workers at the larval stage and thus weakens the honeybee colony. In temperate climates, Varroa mite infestation typically kills an entire colony within three to four years, while in warmer areas, death can occur within just six months. In order to fight against this parasite, beekeepers treat their hives with different kinds of chemicals such as Acaricides or other acidic substances such as Oxalic or Formic acid.
The second contributing factor is the wide and excessive use of chemical pesticides around the world. In order to increase agriculture production, farmers tend to spray more and more pesticides on their crops to protect them from various kinds of insects and diseases. Unfortunately, these pesticides are also toxic to honeybees that forage the flowers of these treated plants. Some classes of pesticides, known to be highly specific, may not kill the bees when used in weak doses, but even at sub-lethal doses, can render the honeybee unable to navigate back to their hives.
An example of this can be found in the neonicotinoid group. These chemicals (such as clothianidin and thiamethoxam) are used in pesticides and have been shown in high doses, to cause the death of honeybees, and in low doses, at even sub-nanogram levels, to impair, directly or indirectly, the ability of bees to navigate back to their hives.,
This demonstrates that honeybees are exquisitely delicate creatures and are influenced by particulate toxicity in the range of parts per billion.
CCD: A Synergistic Phenomenon
Besides the Varroa mite and the use of pesticides, honeybees are facing many other diseases and disturbances that are without doubt contributing greatly to CCD.[19,20] Part of the problem is the increasing urbanisation of rural areas around the world. We have imposed our new modern lifestyle on honeybees and have invaded their territory by destroying their habitats. Nowhere can the detrimental effect of our modern lifestyle be seen more acutely than the discovery made by Decourtye et al. in 2011. This team showed that the radio signal of the mobile phones we so cherish and use daily, as well as microwave antennas, impair the honeybee’s navigation system and affect its capability to orientate itself. Just as with pesticide, such invisible signals prevent the honeybee from returning from the field to its hive.
The age of globalisation that the 21st century has brought the world into has also had subtle and unforeseen consequences on the honeybee. It has been noted that in recent years, there has been a remarkable increase in honeybee death during winter. As an example, in Canada, honeybee wintering losses were reported at 23.8% in 2009-2010. Many reasons could contribute to this, such as a lack of honey stored in the hive resulting in nutritional deficiencies; climate change resulting in unusually cold and long winters and the weak capacity of honeybee adaptations to local environments. It is this last cause that is emerging in many cases as a leading contributing factor. Globalisation in the world has highly facilitated honeybee importation between countries. This means that a beekeeper from the USA can easily bring and keep honeybees originating from Italy or France. However, these bees will not necessarily be adapted to the local environment of the USA. They will have to face new climate conditions, new floras and a different winter from which they were adapted in their original countries. If the imported honeybees cannot develop a rapid adaptation to the sudden changes towards the new conditions and challenges they face, or if the differences between the two environments are extremely different, these bees will have little chance of survival in the new environment.
The jury is still out on the decisive cause of CCD and, as stated previously, it is likely to be a multifactorial problem, with honeybee losses not only due to one factor, but as a result of many causative factors acting together, synergistically, the combined effects on the honeybee population by these negative influences being greater than any one of them individually.
However, one common thread emerges between many of the causes: the overexploitation and industrialisation of this miraculous insect. Man with his new technology is asking of honeybees more than what they can afford to give. Human nature and the desire for more; more production, more honey and more profit; with no consideration of the limited capacity of this insect, should be seriously addressed. Sustainable beekeeping practices should be adopted around the world that prohibit honeybees’ overexploitation, save their natural diversity and protect them from decline.
- Noah Wilson-Rich, The Bee: A Natural History, (Princeton, Princeton University Press, 2014).
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