Social networking, bee style
Bees’ brains are about one million times smaller than ours, but they are still capable of very complex behaviour. For example, they communicate with each other using strange little movements known as the ‘waggle dance’.
When a worker honeybee returns to the hive from a foraging expedition, she performs a ritualised series of moves which is designed to communicate to other workers the location and value of the resource she has just visited. To do this, she swings her body from side to side about 14 times per second while vibrating her wings, usually without moving her legs. After waggling forward (the ‘waggle run’) for a given length of time, she circles back to restart the sequence.
Scientists think that the length of the waggle run indicates the distance to the resource, the intensity of the waggle signifies the value of the resource, and the alignment of the run shows the direction in which the bees should fly (relative to the sun) to find the resource. Followers of the dance appear to interpret it by touching the dancer with their antennae; once they have gathered sufficient information they buzz off to find the resource.
Another way in which honeybees communicate is through the release and sensing of pheromones—secreted chemicals that affect the behaviour of others. For example, worker bee larvae emit pheromones that hinder the formation of ovaries in juvenile workers and stimulate them to produce certain proteins in their saliva that is fed to the larvae. Alarm pheromones (composed of isopentyl acetate and other chemicals) are used to inform the guard bees of emerging threats to the hive and place the other bees on high alert.
The queen also emits pheromones that inhibit the production of juvenile hormones in young workers, which slows their development into worker bees and also prevents them from developing eggs. These queen pheromones are transferred throughout the hive through body contact and also serve as a way for the bees to identify each other and to know that their queen is still in residence.
If some worker bees don’t receive enough queen pheromones (because of too many bees in the hive, or the queen has died) they start building queen larvae cells in order to produce a new queen. These queen cells may be destroyed by other worker bees who have come into contact with enough queen pheromone. Whether or not a new queen cell is built ultimately depends on which group—the builders or destroyers—works the fastest. In this way the bees carry out a type of ‘election’ to determine whether or not a new queen is needed for their hive.