ORIGINAL FRENCH ARTICLE: Il est difficile de trancher
by Jean-Luc Brunet, Assistant Manager of the Combined Bee Research and Environment Unit
Translated Monday 29 June 2009, by
The bee population has been in continuous decline in industrialised countries for about fifty years. However, it has only been for the last thirty years that there has been any systematic reporting on the declining colonies in cultivated areas and also in regions that are not under intense agricultural production. The decline affects not only the size of the bee population but also the number of existing species. Moreover, the decline in the numbers of honey-bearing insects, and in particular the domestic bee, has taken a turn for the worse with the result that since 1995 the problem of the weakening of the apiaries has become a problem of international dimensions. France and Europe were the first victims but now North American bees are also suffering a high mortality rate.
The domestic bee has an important role to play in both socio-economic and environmental activity. Not only does it provide a source of income for the bee-keeping industry, but it is also responsible for the qualitative and quantitative crop yield, because one third of the production is linked to their pollinating activities. Bees influence the environment at the level of vegetal, and therefore animal, bio-diversity. The decline of this pollinator thus constitutes a serious environmental problem for the eco-systems from which human society has high expectations.
This mortality rate could be attributed to a number of factors:
1. The conversion of open spaces to meet human needs, together with increased urbanisation and a reduction in vegetal biodiversity can cause the extinction of species and the break up of habitats, resulting in fewer sources of food.
2. Beekeeping techniques - despite the fact that beekeepers are now better informed and better qualified to care for their colonies.
3. Global warming - which could eventually lead to modification of behaviour within the colony.
4. The increase in diseases linked to parasites (varroa and nosemosis), bacteria and many viruses, although the beekeeping profession is very much better informed about the sanitary management of the hives.
5. Environmental pollutants linked to industrial and agricultural human activity, including pesticides (insecticides, herbicides and fungicides). Amongst pesticides, recent insecticides (known as systemic ) are strongly suspected of having caused the loss of some colonies because they spread through all parts of a plant causing chronic food poisoning to the bees in sub-lethal doses. Chronic exposure of the bees to such doses combined with similar substances found in the environment, leads to behavioural effects that might or might not determine the survival of an individual bee. The level of this toxicity might sometimes turn out to be very high. This method of chronic poisoning is not always taken into account in the evaluation of systemic insecticides when preparing authorisation for their release onto the market.
Most scientific research carried out up to now has focussed on one factor only and has drawn contradictory conclusions. It has been difficult to determine the causes of the decline in the number of bees from research based on a single factor. In the unit for bees and the environment at the National Institute for Agricultural Research (INRA) in Avignon  and other laboratories, we are currently experimenting with combinations of these irritants and the factors already mentioned to set up a hypothetical interaction between them. We hope that this multi-factor approach will soon give us the reason for the decline in the bee population so that we can put a stop to the problem and preserve the ecosystems.
 Laboratoire de toxicologie environnementale (INRA Avignon)