What does inbreeding look like in honey bees?

What if your apiary is isolated enough that most drones come from YOUR hives?

A honey bee queen mates with drones, so she can lay fertilized eggs. Those are supposed to become females - worker bees.

But! If an egg is laid with identical copies of one particular gene from the queen and from the drone, this results in a male worker, AKA a diploid drone, and it dies (or more likely, is consumed by the REAL female workers). This means the frames will show a spotty brood pattern.

This is a model showing how "inbred" the apiary will be depending on:
• How many alleles in the population initially?
• How many drones does the queen mate with?
• What percent of those drones are "foreign", meaning drawn randomly from the starting allele pool?
• How many breeder queens each generation?
• And how many generations out?

TL;DR:
When queen lays a fertilized egg with identical copies of an allele at the so-called "sex-locus", a male honey bee will develop. These "diploid drones" will be eaten by the workers, so they show up as gaps in the capped brood. Too many diploid drones - a spotty pattern where 75% or less of the brood survives - will make for a weak colony.

Many beekeepers in my area let their handful of colonies requeen themselves, which in a short amount of time should lead to spotty brood due to inbreeding with brothers and cousins from one's own hive. Or from nearby swarms that were started from the original colony!

However, we rarely see spotty brood in apiaries where no new queens are introduced. Therefore, most places in Northeast Ohio must have a significant contribution of "foreign" drones.

But if that's not the case... for example, on Lake Erie island apiaries, or even peninsular apiaries, or in apiaries surrounded by flat treeless farmland or dense pine forests... then those hives will suffer in a very short time from inbreeding.

What if you only have 2 queens in your yard for rearing queens? That's only 4 different alleles.
What if your apiary has very few "foreign" drones adding extra alleles? What if there are a lot of foreign drones?

This calculator uses a random number generator to select the "alleles" from the closed population each geneartion - and if an allele disappears from the local population, then it's gone.
Or that allele could be re-introduced thanks to the contribution of some "foreign drones"...go ahead and play!