I was at an interesting talk last night on the Black Bee, but the guy giving it went off into various discussions about queen selection on a small scale.
The following points were raised, and I think I agree with most of them:
- You can't really breed strains of bees unless you have >50 colonies to be selecting from.
- Pure strains will (as Finman has pointed out) be 'watered down' by local stock within 3 years.
- Pure strains often become very aggressive when hybridised.
- Hybridised bees are often very prolific, but not continually prolific and may fail after a few years (hybrid vigour).
- Bear in mind that any colony which produces a large excess of honey is not doing something 'natural' - bees in the wild don't need to gather hundreds of pounds of honey in a season, so those that do are probably overworking themselves.
- Successful breeding isn't about increasing the yield and survival of any one colony, it increases the yield and survival of the apiary as a whole over a number of years.
If you buy a pure strain queen, and want to keep her that way, then you have to expect to buy in a new queen every few years. Otherwise the best an amateur can do is to try to bring on a selection of queens each year (including taking virgins to other apiaries), study wing morphology and other characteristics, and swap out the 'worst' 60% queens from your apiary each year, keeping th best 40%.
As well as the beekeeping-friendly traits you're looking out for (good yield, low aggression etc), also be on the look out for:
Prolific pollen storage, including under the brood.
Small, tightly packed winter bundling.
Low temperature foraging.
As these are signs that the colony will survive well through the winter.
Hope this info is useful, if a little off topic!