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We have seen that bees have many ways to communicate, even including through vibrations on the honeycomb they build. But the most important and powerful communication mechanism is through pheromones. Indeed, the use of pheromones within the colony is essential for communication of events, the status of their health and much more.
Bees have one of the most sophisticated pheromone-driven communication systems in all of nature, with all three castes having the ability to signal other bees through pheromones.
Let's look at the wide variety of ways in which pheromones are used and why they are so essential to bees.
Pheromones are in widespread use throughout nature. A pheromone is a chemical substance released into the environment by an animal, for the express purpose of changing the behavior or physiology of others of the same species.
One of the most well-known examples of the use of pheromones by ants, such as when they establish and can then follow a trail. But many other examples exist such as in rats, moths and flies - even underwater.
Sea lampreys have caused havoc in some parts of the fishing industry, so scientists are investigating how the sea lamprey's own sex pheromone can be used to quell the chaos they cause.
There are deceptive uses of pheromones in nature too. Many orchids fool bees into visiting them - and thus helping with pollination - by counterfeiting the pheromone of a particular bee species. The effort necessary for the plant to create this pheromone to attract bees is lower than that necessary to offer the real reward of nectar!
Nature is incredible.
With this background, it's clear to see that the use of pheromones in the close confines of a bee hive can be a powerful force. And indeed, it is!
Many key messages are sent through using pheromones. As we will see below, these range from relatively localized messages, with minor impact, to dramatic signals that rapidly change the behavior of the entire colony.
Bees use pheromones in almost all aspects of their life. This includes reproduction and development of brood, mating, swarming, foraging, defense and more. Given the widespread use of pheromones, they can be considered the single most important way in which bees communicate.
As is the case with many animals in nature, bees use two types of pheromones:
Let's look at the various pheromones that might be floating around in your beehive!
The Queen Mandibular Phereomone (QMP) is perhaps the most important pheromone, from the perspective of the colony. It is composed of five compounds, is secreted by the queen and essentially sends a message of "queen well-being" throughout the colony.
QMP is interpreted in various ways and plays a role in the suppression of egg-laying by worker bees, swarming and in attracting drones when mating.
The worker bee response to QMP is an example of a primer pheromone at work, where the presence of QMP will stop their ovaries developing.
As worker bees encounter the queen, they will collect tiny amounts of QMP on their bodies. As they move around the hive to administer their various duties, they spread QMP throughout the hive very efficiently. Through this mechanism, the colony expects certain levels of QMP to signal a healthy queen.
When the "per bee" QMP levels fall below a certain threshold, this may be interpreted as meaning the colony is too large. In these situations, swarming may result, to reduce the number of bees in the beehive.
The group of worker bees that follow the queen around tending to her needs is referred to as the queen retinue. The Queen Retinue Pheromone (QRP) is complex, with both primer and releaser characteristics and has a direct effect on the queen's retinue. It can be considered a superset of QMP since it is composed of the five compounds of QMP, plus four more.
The complexity of pheromones in bees is illustrated well by the two types of alarm pheromone, which can be distinguished by the gland releasing the pheromone.
This pheromone is released by developing larvae and pupae. It signals to worker bees that brood continues to develop in the hive, which like QMP, limits the development of worker ovaries.
Drone Congregation Areas (DCRs) are used as consistent places, year after year, for drones to gather and mate with queens. The drone pheromone is released by male bees to attract other drones to DCAs.
This pheromone is evident on eggs laid by a queen. This allows workers to distinguish them from those laid by a worker bee, the former being more attractive.
This has a similar purpose to the DuFour's Gland pheromone, in that it helps worker bees distinguish between queen and worker-laid eggs.
An important pheromone released by worker bees to help returning forager bees find their way back to the colony. Workers raise the abdomen and fan their wings as they release this pheromone.
This has a similar "find home" purpose and is deposited as bees walk around the hive. The queen also emits this as she moves around the hive. This signals that there is no need for the colony to consider creating a new queen, since she is still active.
Older foraging bees release this pheromone, which collectively signals the presence of forgers in the colony. This, in turn, inhibits the creation of nurse bees, to keep the ratio of foragers to nurse bees within appropriate limits.