Ecological Artificial Life - contents

Chapter 2. Literature review and background for the project

Honey bees are an example of a social insect. They are perennial, meaning that they don't hibernate, and some bees (other than the queen) will survive from one year to the next. This means that the hive can become operational in the spring more quickly than if the queen had to wait for all the new eggs to hatch.

They have two genders, and three castes: drones are male, whereas queens and workers are female. However, only queens are fertile (barring exceptional cases when a hive has no queen). Unlike humans, bees have no Y chromosome; females are XX, while males are simply X (haplites). A female larva could develop into either a queen or a worker, depending on whether it is fed royal jelly. So, a worker lava can be turned into a queen larva, as long as it is less than three days old; this may become necessary if the queen dies unexpectedly.

There are four stages to a bee's life-cycle: egg, larva, pupa, and adult. The first three stages are collectively known as "brood".

The queen sends signals to the other bees via pheromones, which tell them not to create any more queen larvae. However, when the hive grows these pheromone signals get diluted, so new queens are raised. At this point there will be a swarm, where the old queen leaves the hive, taking approximately half of the bees with her. This may be followed by one or more casts (mini-swarms), as new queens hatch, until the population drops to a sufficiently low level. The last queen (princess) left at this point will inherit the hive; any unhatched princesses will then be killed.

Normally, there will only be one queen in a hive at any one time. However, it is possible for an old queen and a young princess to co-exist in the same hive, when the old queen is being superseded.

Aside from the swarm, a queen will only leave the hive at one other time; early in her life, she will make a mating flight. This enables her to mate with 10-15 drones from other hives, where she will store their sperm for future use. (This is fatal for the drones concerned.)

Drones only have one purpose in life, which is to mate with a queen. They are incapable of fighting, or even of feeding themselves, and they rely on workers to do it for them. The hive will raise drones in spring and summer, but after this they are surplus to requirements, so they are forcibly evicted from the hive by their sisters, and left to starve to death outside.

Workers take on various roles. Typically one bee would perform several tasks during her lifetime, but there is no fixed schedule for this. These roles include:

Seeking out new locations.
Following the scout to gather pollen and nectar (two distinct tasks within the forager group).
Honeycomb construction
Building a comb from wax, and shaping it into hexagonal cells.
Capping cells
Putting a wax cover on a cell to seal in a larva before it begins metamorphosis.
Sitting on the outside of the hive, and evaporating water droplets with wing movements to lower the air temperature inside the hive.
Feeding larvae.
Protecting the hive from robber bees (from other hives) and birds.
Removing dead bees from the hive, or embalming corpses that are too large to remove (e.g. mice). This prevents the spread of infection.
Water collector
They will gather water from puddles, but risk drowning.

If a bee stings a bird or animal, she dies, since the sting (and venom sac) is ripped out of her body. (Drones don't have stings.) This makes the sting an effective weapon for defending the hive, although it can only be used once. By contrast, a bee can sting another insect and survive.

Workers are also capable of laying eggs, although since a worker will never mate, her eggs will always be unfertilised, i.e. they will become drones. It was previously thought that this was quite unusual. For instance, Powell [3, p51] refers to "the very rare occasions when a worker is able to lay an egg". However, more recently it has been discovered that worker policing goes on. Basically, workers will frequently lay their own eggs, but they will also destroy each others as long as they are receiving queen pheremone. It's not that the queen is actually telling them to police each other, rather that workers are more closely related to the queen's offspring than to each other's. This is related to the concept of the coefficient of relatedness, as discussed by Hamilton.

More generally, this highlights one challenge in the literature review - there can be conflicts in the information published by different sources, and more recent articles can overrule older ones. So, it is possible that some of the assumptions I've made in this simulation are now out of date.

Next: 3. Design and Specification

This page was last updated on 2004-09-05 by John C. Kirk

Valid XHTML 1.0! Valid CSS! Level Double-A conformance icon, W3C-WAI Web Content Accessibility Guidelines 1.0 Labelled with ICRA