Mortality

This post is also available in: Français (French)

Statistics on the evolution of bee populations are very difficult to obtain. And yet it is widely acknowledged that bees in France are subjected to various external factors, the best known of which we list here.

In recent years, the beekeeping world has been faced with a strange phenomenon: a growing number of hives that empty out in less than a week. The scale of the phenomenon leads observers talk in terms of a disaster, but nonetheless a mysterious disaster, because the bees disappear “cleanly” without leaving any bodies, abandoning hives full of honey and pollen and not raided by other bees or insects.

In the USA, this syndrome has been labeled Colony Collapse Disorder (CCD).

We should however apply a measure of perspective, since massive bee mortality has been reported from time to time for many centuries: the first recorded case was observed in 950 in Ireland.

What are the causes of CCD? There is currently no clear explanation for the disorder. Many agree with research findings that point to multifactor causes, the possible components of which are:

1 – Pesticides and fungicides

One important cause could be the widespread use of seed coated in systemic pesticides, which applies to both conventional crops and genetically modified ones. In particular, the widely used application of a relatively new class of systemic insecticides, the neonicotinoids, which are highly toxic to insects including bees in very low concentrations. It is accepted that one the bee’s main vulnerable points is the mere fact of being an insect and therefore being highly susceptible to insecticides designed to protect crops. Its second weakness is its low capacity to resist and to mutate. Other “wild” insects have retained the capacity to mutate very quickly.

American researchers are not convinced about the role these molecules play in CDD but they concede that affected pollinating insects might have more difficulty in finding their way back to the hive and thus contribute to colony depletion.

2 – “Electrosmog”

Numerous studies concerned with either CCD or bee poisoning by pesticides have identified a common denominator: Bees loose their direction-finding ability and cannot make their way back to the hive.

Some researchers put forward the hypothesis that modern so-called third generation mobile phone technologies, whose aerial masts are increasingly widespread in Western countries, are having an impact, given the extreme sensibility of bees to electromagnetic fields.

3 – Intensive apiculture

Modern Western apiculture, like modern agriculture, is based on high productivity, the intensity of which may be an incriminating factor:

  • over-populated hives, with an antiseptic environment due to antibiotics and acaricides
  • large-scale transhumance, in which bees are moved to targeted monocultures
  • fields drenched in fungicides, insecticides, herbicides
  • artificial insemination of queens
  • excessive extraction from honey reserves
  • culling millions of queens on the 8th day of their development to harvest the royal jelly.

The USA, which has a more intensive approach to beekeeping, is more affected by CDD than France, but certain recent studies have tended to eliminate these contested beekeeping practices from the list of causes of mortality in France.

4 – Parasites

  • The mite Varroa destructor. This Asian mite has gradually spread through Europe and the Americas since the start of the 1960s, with Australia now the only varroa-free region.
  • Acarapis woodi, a microscopic mite that is an internal parasite of honeybees. The female lays eggs in the bee’s trachea. It has been widespread in the United States since 1984 and has been spreading in Europe since 2007.
  • A new nosemosis caused by the protozoan Nosema ceranae. It is already present in Spain and cases have been recorded in France. This protozoan is one suspected cause of CCD but it should be noted that it has been present in the USA for more than a decade.
  • The small hive beetle Aethina tumida. A newcomer from Africa which has swept through the USA (since 1998 in Florida), Canada and Australia. It is thought to have reached Portugal.
  • Another acarine disease is caused by Tropilaelaps clarae and Tropilaelaps koenigerum. They are not yet present in Europe but are thought to have reached Australia, which represents a risk of contamination for the USA since many farmers there depend on bees from Australia for pollination.
  • A new predator for bees is a hornet called Vespa velutina nigrithorax, endemic in China, in Bhutan and northern India, it was accidentally introduced into France in 2004. The Asian hornet builds nests high up in pine trees and reproduces rapidly in the absence of natural predators. It attacks bees on the wing.
  • A recent American discovery based on systematic screening for 19 known diseases in the case of CCD shows that IAPV (Israeli Acute Paralysis Virus) is the only parasite which was found to have a significant connection with the syndrome. Although these findings make IAPV a strong suspect, it is no doubt not the only cause of CCD.

The range of studies leads researchers now to think that there is not one single cause that explains CCD. Research is now tending towards interactions between pesticides and diseases, possibly including some hitherto unknown pathology.