Dangers of Double brood box.

[prakel]

If you had a small or average size colony which attempts to swarm itself out with prime swarm followed by several casts etc that would be an issue
When a large colony gets ready for swarming that's something else

Reading back through the op it doesn't actually look like the colony in question was particularly large. OK, a single queen must have been laying at an eye watering rate if those 13 combs were solid brood... However it seems as if the real trigger here may have been the extensive feeding combined with injudicious use of the queen excluder; failing that, then they probably went way too soon. Either way, we don't know for sure so as a default Duncan's reasoning is sound.

[GRIZZLY]

Would you use superceedure cells Duncan ??

[Duncan]

I suppose it also depends on the type of hive in use. We use langstroths, a single brood chamber with ten frames and a queen excluder most of the time. This large enough for our bees. The maximum egg laying rate is about 1500 eggs per day, which equals five full frames of brood. This might be spread over the eight to ten frames of the broodchamber. The bees rarely swarm and when they do we know which line they came from, it is scrubbed from the breeding program and all sister queens are changed as soon as possible.
There is an acute swarming problem in Greece with unselected bees, John Phipps - editor of the BKQ, has written several times in the BKQ about the problem. Give them as many frames as you like: 20, 30, 40 - as soon as the population reaches the seven to eight frame size they go into swarm mode. Imagine what happens when 1,5 million colonies swarm. It happens most years just at the time when the bees should be collecting the spring crop. The colonies don't have any emerging brood for up to about 6 weeks and this in turn does a lot to reduce the summer crop. See how expensive swarming can be! Few beekeepers realise the cost.

[prakel]

There seems to be a lot of confusion with regards to how many bees make up a colony, Duncan's description of their bees is in line with the figures suggested by Jamie Ellis who's starting to research colony size (mentioned in the question/answer section of one of his NHS talks). Oddly a lot of people have colonies far larger than one queen could ever realistically support.

[Duncan]

Longevity also plays a role. The light yellow Italian type bees are very prolific but also quite short-lived. Anatoliaca have a long life span and the same probably applies to the AMM group.

Some colonies have 2 queens.

[prakel]

Longevity also plays a role. The light yellow Italian type bees are very prolific but also quite short-lived. Anatoliaca have a long life span and the same probably applies to the AMM group.

Out of interest, am I right to think you're saying that colony size can be positively incresed in the case of longer lived bees? My instinct would have been to assume that the two extremes would probably result in an overall levelling so that the average colony sizes would be similar between prolific short lived bees and less prolific longer lived ones. I do realise that this is a very simplistic way of looking at a complex issue but it's potentially also a very interesting subject which is worth a deeper look.

[Duncan]

There is obviously a point at which die-off reaches an equilibrium with hatch and may even exceed it. Sometimes we see that the adult bee population in a hive is not justified by the amount of brood. I suppose it depends on the time of season and what happened in the previous 3 months. We see that some of the anatoliaca Buckfast lines just build-up from nothing in mid-spring, having given the impression that they aren't going to do much 4 weeks earlier. There are 3 frames with brood and then suddenly there are 8 within 2 weeks. When traveling around in Greece I sometimes see large populations of bees in mid-spring with a relatively small amount of brood. My thoughts are that it is all down to longevity, but I'm not there later to see what happens - they probably swarm anyway.

[mbc]

The bees rarely swarm.

Nor do mine, in their first full season, and rarely in their second. When they do get passed the first flush of youth they do tend to swarm, but the drones they've produced are in line with local drone population which in turn will hopefully provide beneficial mating to the virgins they leave behind. A sustainable vision without the need for continual outside inputs that doesn't pollute the airspace for others.

[Duncan]

Jolly good for you MBC.

Information from a RBI contact is that the AMM colonies are dropping like flies and Buckfast has a much better resistance to CBPV.

You may still get your wish to stop all imports when the vote goes for a BREXIT. So maybe the 2016 queens will be the last ones imported from the EU.

Sometimes, however, you have to think carefully about what you wish for.

[fatshark]

Information from a RBI contact is that the AMM colonies are dropping like flies and Buckfast has a much better resistance to CBPV.

Presumably this is descriptive observation rather than actual testing? i.e. CBPV has been observed adversely affecting AMM colonies, but not Buckfasts? Is it known whether the latter were exposed? Maintained using the same beekeeping practices? Have the same history of Varroa control? Forage? Climate?

I'm not saying that there aren't differences in susceptibility to pathogens, just that describing what is seen is often only half the story.