Drone surrounded by worker bees. © INRA, MORISON Nicolas

Scientists flying to the rescue of bees

Bees: a worrying decline

One image, which comes from China, is enough to shock us: dozens of children, standing on the branches of apple trees, are pollinating their flowers one by one with a brush because of the lack of compatible pollen and an absence of pollinating insects. This is what the world would be like without pollinators, without bees. Although China is an extreme case, the decline of bees is indeed a global phenomenon, seen in a wide variety of countries. In the USA, for example, the situation is really dramatic: losses are as high as around 35%, with some catastrophic periods such as the winter of 2006-2007, during which nearly half of all colonies disappeared. For at least the past ten years in France, around 25% of colonies have not survived the winters, while the normal rate should be lower than 10%. It is however difficult to be absolutely precise: on the one hand, beekeepers do not always notify their losses, and on the other, the reality in the field is too complex to be understood using simple indicators. A few data have nonetheless been collected by the French Bee Institute (ITSAP): Alsace seems to be the worst affected region of France, with 35% of winter losses every year during the period 2008-2011, followed by Midi-Pyrénées, which reported 28% of losses. The Provence-Côte d'Azur region (PACA) and Corsica lower the national average (25%), with losses of around 17%.

Updated on 03/27/2017
Published on 05/01/2014

Several reasons for a global phenomenon

What is the explanation for this phenomenon that affects China as much as France, the USA as much as Belgium, the UK or Spain? That is a major challenge for science. Indeed, no researchers now claim to be able to advance a single cause for the losses faced year after year by beekeepers.

At present, the decline of bees is attributed to three principal and constantly interacting causes. The first is pesticides, whose subtle effects on bee physiology are now starting to be understood. Secondly, pathogens and predators are exerting increasingly strong pressure on weakened colonies. The final reason is environmental change and intensive agriculture, which in many areas have deprived bees of consistent, good quality food sources. However, it is currently impossible to rank these causes and determine that with the greatest impact on bee colonies.

Bees labelled with coloured discs to create different cohorts. © © INRA, MORISON Nicolas
Bees labelled with coloured discs to create different cohorts © © INRA, MORISON Nicolas
Other reasons have also been put forward: poor beekeeping practices, for example, or climate change. Researchers do not really believe the former: beekeepers are increasingly knowledgeable, and apart from occasional accidents it is impossible to render them responsible for a decline in their livestock. Nor is much credence given to the latter theory, as European bees are capable of acclimatising equally well to Mediterranean and continental conditions. That is unless global warming has an indirect effect; by favouring the proliferation of insects, it may encourage farmers to increase the doses of pesticides they apply to their crops.

A bee counter: Big Brother in the hive

Modern and efficient, the bee counter developed by the INRA Joint Research Unit for Bees and the Environment, will be warmly welcomed by both researchers and beekeepers. Comprising a box equipped with a camera, this device can count bees one by one as they enter or leave the hive. By marking some individuals with small numbered labels, it is also possible to determine the times they enter and leave, or even their life expectancy. This represents a tool of considerable value to determine the effects of pesticides, pathogens and pests. This bee counter, which will soon be marketed by the company Apinov, obtained the World Beekeeping Award 2013 during the international congress Apimondia.