Recent years have seen sharp declines in bee populations, with UK numbers decreasing by 45% in the last 5 years. This is not only concerning for the environment but for the world as a whole, as pollination by bees is responsible for approximately 30% of foods consumed in the human diet. For tens of millions of years bees have survived and thrived, keeping themselves healthy and avoiding extinction, so why are we seeing such drastic declines in their numbers?
The main reason for this decrease is Colony Collapse Disorder (CCD), a phenomenon first described in 2007 in the USA after population decreases of 25% were observed across 27 states. Though the bees in the colony were extremely sick, no dead bees were found inside the hive. This is likely due to sick bees committing altruistic suicide, moving far from the hive to die alone in order to prevent the spread of infection. Though no single factor has been determined to be the cause of CCD, many different theories have been put forward.
The first suspect was a honeybee parasite known as the Varroa mite, which attaches itself to honeybees and feeds on their blood equivalent, haemolymph. The loss in haemolymph weakens the bee and makes it more susceptible to viruses and other pathogens which can cause sickness. However, several beekeepers and biologists noted that the onset of bee deaths and colony collapse were too quick to be the result of a Varroa infestation, and the mites were not always present in CCD cases. Some have suggested that new viruses or other pathogens may have developed and are responsible for CCD, although none have been isolated as of yet.
Changes in farming practices were then suggested to be the cause. Since the mid-1900s, farming methods have become more reliant on synthetic fertilisers rather than natural ones, and the use of pesticides and herbicides has become far more prevalent. Samples of pollen collected by the bees from crop plants have been found to contain traces of pesticides and herbicides, and consuming them could have negative impacts on bee health. Neonicotinoid pesticides have been making headlines recently, and though a direct link to CCD has not yet been identified it has been known to cause intoxication, disorientation, uncontrollable twitching, and even death in bees that consume it through tainted pollen. Nutritional stress on the colony may also play a part in CCD.
Additionally, the loss of flowering plants due to land being built on, as well as crop monocultures created for farming, leads to a loss in nutritional supply for the bees, weakening them and making them more prone to other threats.
So what is the cause of Colony Collapse Disorder? The consensus is shifting towards a combined effect of all of the above, with colonies first being weakened by one factor and then killed by the others.
Though work is being done to reverse the population decrease and restore bee numbers as much as possible, others are developing alternatives to bee pollination. Researchers at Harvard University have developed a “robobee” which could be used to pollinate plants, and vibrating equipment is often used by people to release the pollen from plants in a way that simulates bee vibration and allows the pollen to be collected and used for manual pollination. However, these methods are not solutions, and for the moment are only efficient enough to be used complimentarily to natural bee pollination.
Though this all sounds rather ominous, there is some good news to come from this. As the news of bee decline and Colony Collapse Disorder spreads, more people are making an effort to help the bees. Many beekeepers are offering beekeeping classes and encouraging people to start their own colonies, and efforts have been made to grow flowering plants favoured by bees in parks, cities, and private gardens. Though the underlying problems of CCD still need to be resolved, these efforts are offering hope for the world bee population.
If you’d like to help save the bees, get in touch with Sheffield Beekeeping Society!