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Drone surrounded by worker bees. © INRA, MORISON Nicolas

Scientists flying to the rescue of bees

Alien predators

There is no doubt that bees have good defences in the form of stinging and poison, but they nevertheless remain prey to numerous animals. These of course include the usual insect eaters such as spiders and mantis, flies and predatory wasps. Birds such as the bee-eater or swallow do not hesitate to catch foraging bees in flight. And mammals should not be forgotten: bears or badgers are attracted by honey and may pillage colonies, and rodents may feel warm and safe in the shelter of a hive. These predators do not constitute a major threat to bee populations: together, they operate in an ecological equilibrium. The real danger comes from invasions of animals from distant ecosystems, who in Europe find an environment that contains plentiful food and few natural enemies. Of these predatory species, that which is currently top of the list and constitutes a threat to the bee industry is of course the yellow-legged hornet.

Updated on 03/24/2017
Published on 05/01/2014

A killer drone that keeps watch on hives

The most recently arrived honey bee pest in France, the yellow-legged hornet (Vespa velutina) made its first appearance in the Aquitaine region in 2004, brought in on a boat from South-East Asia. This social hymenoptera has become a focus for major concern among beekeepers, testified by the fact that in 2012, a Government Order included it on the list of health threats to honey bees.

Voracious and rapid, the hornet positions itself in early July near the hive entrance so that it can catch the bees in flight. It decapitates them and then carries the bodies back to its nest to feed its larvae. A study performed on ten hives at INRA in Bordeaux showed that they were visited by 300 hornets each day, or in other words, 30 hornets per hive each removed up to four honey bees, which was sufficient to damage the colony! But that is not all: in order to protect the hive entrance from invasion by the hornet, the bees neglect their foraging duties. As a result, they soon find themselves short of food.

Few effective methods are available at present to defend honey bees against yellow-legged hornets. Destroying their nests, notably in the autumn, and trapping colony founders, are some techniques that are employed. However, the efficiency of the latter method is now being called into question. Diversion traps situated around hives can also reduce the pressure on bees. It should be noted that the hornet is also becoming a nuisance to humans in urban and peri-urban areas, to which it is attracted by town-based beekeeping and the presence of waste.

Agiir: mobiles against hornets

logo Agiir. © Inra
© Inra
Would you like to participate in the fight against yellow-legged hornets? There is nothing simpler, thanks to a mobile phone app developed by INRA in Bordeaux (in French). If you encounter a hornet in a town or in the country, you can use this app to report your observations to the research team. You will be asked to supply your position and the time of the observation, and to describe the environment around you. This citizen science project will help to determine the preferred habitats of hornets, where they nest and their habits. It will provide a wealth of information that will help to better target and fight against this hive assassin.