The Varroa parasite

Varroa destructor is a parasite that affects bees and causes disease. This mite resembles a louse in appearance and attaches either to a bee larva or to an adult bee in order to feed on its fat body. This condition can lead to the sudden death of bees within only a few weeks. It affects hives and causes very large losses in colonies, which then decline sharply. 

The mite reproduces an external covering similar to that of the bee in order to blend in and deceive them. The bees do not suspect that it is a foreign body and lower their defences more easily; they do not carry out their hygiene behaviours and are then infected by varroa, also called varroa destructor given that it destroys colonies in a very short time, and bees have great difficulty resisting it.

See also:

• Varroa destructor
• Varroa destructor, a killing machine
• Fighting varroa

The Asian hornet

One of the greatest threats is the Asian hornet. First observed in France in 2005, the Asian hornet (also known as the velutina hornet) is the major animal-origin threat to bees. This insect, measuring between 2 and 3 centimetres (slightly smaller than its European cousin, the European hornet), is particularly fond of honey bees; it has made them its preferred prey in southern France, where it has been established for 15 years.

Imported from China in the early 2000s, Asian hornets have acclimatised to their new habitat given the abundant food available (fruit, insects) and the limited presence of predators that could harm them (some birds such as the red-backed shrike, the European bee-eater, or the European honey-buzzard). As a result, for more than a decade they have been ravaging European beehives, and French beekeeping finds itself powerless in the face of this new threat, added to the many that already exist.

The velutina hornet is a very aggressive and virulent species that does not hesitate to attack humans as well as animals. To prey on bees, it hovers in front of a hive, waiting for a foraging bee to come out so it can attack it and either devour it or use it to feed its larvae. It can also enter the hive directly if it has a great need for food; the hornet then causes irreparable damage before leaving, satiated. It is estimated that around thirty Asian hornets can easily overcome a bee colony of 30,000 individuals!

Unfortunately, bees have only a few defence mechanisms against these formidable predators; their stings merely slow hornets down without significantly affecting them. They do, however, have a solution that requires a great deal of energy and many individuals to stop this enemy: bees suffocate the hornet by forming a “bee ball” around it, then begin to vibrate their wings and abdomen in order to increase the temperature inside the ball. The hornet cannot withstand such a temperature; it is literally cooked. However, this technique is effective only when the hive faces a few individuals. Against several dozen hornets, it can generally do nothing and is almost always defeated. Once the colony has been decimated, Asian hornets mainly take the larvae and royal jelly present in the hive to feed their own.

To date, there is no completely reliable solution to eradicate this pest without affecting other innocent species, because traps and pesticides could also risk harming bees, bumblebees, or other pollinating species. The most effective method is to destroy the nest, either by one’s own means (using appropriate equipment and solutions) or by calling in authorised professionals.

 

Counter-attack by a bee colony facing Asian hornets. 
Source: National Geographic (YouTube)

See also:

• Vespa velutina, Asian hornet
• Apiservice quick reference guide

Pesticides / insecticides

Another threat, this time linked to humans, is pesticides and insecticides. Indeed, it was in 1995 that insecticides emerged in Europe. Since then, more than 300,000 hives die each year, which halves honey production and can therefore explain its steadily rising cost. France is the leading honey-producing country in the European Union but ranks third in terms of pesticide use. This has an alarming effect on bee mortality. It is important to recall that bees are very important in our ecosystem and that 75% of food production depends entirely on pollinating animals, and thus largely on bees. Phytosanitary treatments are a major threat, among many others, and must be regulated at all costs! 

In addition, it should be noted that a “chemical cocktail” now exists, meaning a powerful mixture of different pesticides. For example, a bee can be exposed to 7 different pesticides within a single pollen sample. Today there are many associations, such as Greenpeace for example, that fight to regulate and/or completely stop the abusive use of these pesticides.

 

In addition, there are very many insecticides, and some can be much more powerful than others. This is the case for neonicotinoids, a family of pesticides 100 times more powerful and therefore more deadly than others. Yet these are the ones most commonly found. According to Greenpeace, 80,000 bees can be killed at once with a single grain of maize coated with these pesticides. Finally, if killing many animals (because it is not only bees that are affected by pesticides) does not seem to bother some farmers, what about humans? These pesticides ultimately end up on our plates, in small or large quantities… “Scientific data are clear and show that the potential harmfulness of these pesticides is far greater than all the advantages they could provide in terms of pest control and increased agricultural yields,” Greenpeace estimates.

There are now laws and labels, such as the Bee Friendly label for example, which enables large retailers to select products that comply with this label. This is therefore a beginning of protection for bees; however, Europe is still slow to take measures to protect them. Certain products were banned in 2018, but it appears that they could be replaced by other products that are just as harmful. Since 2013, there has in particular been a guide, but it still has no legal value, for lack of agreement by the EU to recognise it officially. This guide would allow a “test” of many pesticides and certify their damage to animals. It has been shown that, if this text were approved, more than half of pesticides would be recognised as extremely dangerous… In conclusion, we are still far, even very far, from adopting concrete measures to limit or completely eliminate the use of pesticides, even though everyone seems to be aware of the proven damage they can cause to bees and many others. 

 

See also:

• Neonicotinoids

Climate change

Finally, the last threat that bees suffer from is climate disruption. Bees, like many pollinators, orient themselves using visual and olfactory signals, for example to memorise a scent and associate it with a plant. A bee’s olfactory memory allows it to know, simply from a scent, whether a flower contains nectar that is rich or poor in sugar, or even whether the flower contains no nectar at all. Climate change on Earth causes changes in floral odours in certain plants, notably due to drought or a strong rise in temperature. This change in floral odours (in general, it involves an increase in molecules, which intensifies the odour) is due to stress experienced by plants because of climate change. This leads to a loss of orientation for bees, which can no longer correctly associate an odour with a plant. These climatic changes affect the production of floral resources first and, as a result, the bees’ harvest second. If plant flowering is less productive, bee foraging will inevitably suffer. In the long term, this can lead to pollen shortages, reduce or even stop egg-laying. Thus, bee renewal no longer occurs rapidly, creating premature ageing of the colony, which may be threatened with disappearance.

Regarding their hive, bees are at the mercy of the weather. Indeed, in the event of heavy rain, their hives can easily be flooded and destroyed due to flooding. In addition, if a fire breaks out near the hive, bees have no way to protect themselves against the flames; the hive will then be charred if it is affected. During periods of very severe heatwaves, it is possible that the wax melts, trapping the queen and her colony.

To cope with these high temperatures, bees have a system to ventilate or warm themselves depending on the ideal temperature they want to approach; nevertheless, it is possible that sometimes they can do nothing against the temperature because it is too high for them and they can no longer even ventilate.

Waves

Alongside these four threats already proven, a fifth threat for bees could exist, but studies on the subject are still lacking to be fully certain. It concerns electromagnetic waves. In today’s society, electromagnetic waves are omnipresent with all the technologies that humans have developed and invented. Daniel Favre (scientific collaborator within the Laboratory of Cellular Biotechnology at the Swiss Federal Institute in Lausanne) published a scientific article between June 2009 and April 2010 after conducting an experiment on a beehive. He placed two mobile phones, communicating with each other every five minutes, near a hive and recorded the sound coming from inside the hive when the waves were emitted. The audiograms showed that bees reacted strongly to these waves (they became nervous and agitated) through the piping of worker bees (a signal of a disturbed hive or the beginning of the swarming process) emanating from the hive. He repeated his experiment in the winter season when telephone traffic was strongest and reported the same result. His final hypothesis was that electromagnetic pollution (the term “pollution” is used here because waves are omnipresent in our current society) would be the probable cause of bee disappearance, particularly in winter when they have no chance of survival outside the hive.

However, the theory that electromagnetic waves would be fatal to bees remains controversial. Other studies were later carried out on electromagnetic pollution with respect to insects and show that waves harm them. This is notably the case for cockroaches, which, when exposed to mobile-wave emissions over a long period, lose energy, increase their amount of waste in the organism, and block the agent transmitting information at the neurological level.

Marianne Tschuy, working for the bee health service in Bern, explains that there are also studies showing that waves have effects on the waggle dance (the bees’ communication system used to transmit a set of messages within the colony). She qualifies her remarks by saying that these study results do not allow one to assert that waves are responsible for colony losses during the winter season.Regarding their hive, bees are at the mercy of the weather. Indeed, in the event of heavy rain, their hives can easily be flooded and destroyed due to flooding. In addition, if a fire breaks out near the hive, bees have no way to protect themselves against the flames; the hive will then be charred if it is affected. During periods of very severe heatwaves, it is possible that the wax melts, trapping the queen and her colony. To cope with these high temperatures, bees have a system to ventilate or warm themselves depending on the ideal temperature they want to approach; nevertheless, it is possible that sometimes they can do nothing against the temperature because it is too high for them and they can no longer even ventilate.

With the advent of 5G, it would be worth looking into the subject before a possible extinction of bees, so dear and vital to our ecosystem.

 

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Sources: 

https://www.futura-sciences.com/planete/dossiers/zoologie-abeille-sentinelle-ecologique-684/ 

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