In honeybee hives, a surprising phenomenon regularly occurs: worker bees can turn against their own queen to replace her when they deem her too weak. This practice, called supersedure, plays a key role in the survival of wild colonies but poses problems for modern beekeeping, where hive stability is essential for crop pollination and honey production.
Researchers from the University of British Columbia discovered that viral infections are often at the root of these revolts. By studying infected queens, they found that their ovaries shrank, which significantly reduced their ability to lay eggs. A healthy queen can lay up to 3,200 eggs per day, exceeding her own body weight, but a sick queen sees her production drop. This decline in fertility is accompanied by a decrease in the production of methyl oleate, a pheromone that normally maintains worker loyalty.
The queen is marked here.
Illustration image Pixabay When the level of methyl oleate drops, worker bees perceive this decrease as a warning signal. They then begin to raise a new queen in special peanut-shaped cells, called supersedure cells. This collective coordination allows the colony to quickly replace a failing leader, but in hives managed by beekeepers, this process can lead to interruptions in egg-laying, weaken the colony's population, and reduce pollination activities.
Beekeepers have reported for years that queen failure is a major cause of winter losses. Viral infections, often spread by varroa mites, disrupt the chemical balance of the hive. To counter this problem, researchers tested synthetic pheromone mixtures including methyl oleate. In field trials, colonies receiving this supplement were much less likely to raise new queens, thus offering a potential solution to stabilize hives during critical periods.
Although there is currently no direct treatment for viruses in hives, better parasite management can give queens a better chance of staying healthy. Bees pollinate approximately one-third of global crops, making their well-being important for food security and ecosystems.
The impact of varroa mites on bee health
Varroa mites are external parasites that cling to bees' bodies and feed on their hemolymph, the equivalent of blood in insects. These parasites weaken bees by transmitting various pathogenic viruses to them.
Among these viruses, some specifically target the reproductive organs of queens, causing ovarian atrophy. This damage reduces egg-laying capacity and disrupts the production of royal pheromones.
Beekeepers must therefore implement rigorous control strategies, such as using acaricide treatments or biological methods, to maintain varroa populations at an acceptable level and protect the overall health of the hive.