Dear friends:
It seems to me that we are discussing only two points here, besides the usefulness of double queen colonies:
1) Is timing different in DQCs and in SQCs?
2) How long before the end of the flow should the laying be halted, so the presence of brood/young bees won't lessen honey producing?
About the point (1) Michael agreed with me by saying
> Other than multiplying the advantages AND
> disadvantages by two, no. The timing is the same.
I do believe that, although I'd replace the "multiplying by two" for a more cautious "increasing".
But the point (2) still seems disputable. First, I have to swear to you that I'm already pretty convinced that this procedure can be useful, at least for european bees (AHBs are much more rigorous about their queen, and I'm not sure that caging the queen for a long time will keep the bees working calmly). So, please, no needs to keep explaining me the benefits of this method
Michael said:
> No. Not the last few weeks of the flow.
> The last few weeks BEFORE the flow.
> Those bees reared DURING the flow are just
> dependants using up resources (honey and
> pollen), gathering no honey and tying up
> bees that could be foraging taking care
> of them.
If you are talking about few (two) weeks before the (very short/two-week) flow, I can agree, but, in this case, you are saying exactly the same as I did.
But if you refer to a longer flow, let's say 8 weeks like the Rick's, so I'm tempted to disagree. First, I think there's a little conceptual flaw in this reasoning (or I didn't get it correctly). Honey production doesn't depend on field bees only. Younger hive bees, the nectar processors (receivers and ripeners) are an equally important task force. Seeley (Wisdom of the Hive) found that as many as half of the bees in a normal colony (with a laying queen) can be involved in this task when the flow is heavy. That's in agreement with the considerations of Crane (Bees and Beekeeping) and Sammataro and Avitabile (Beekeeper's Handbook) for whom, in a large colony, about only half of the bees are foragers.
Nectar processors usually start their tasks by 10-11 days after the emergence, but, if there's no brood to tend, and there's a heavy flow to gather, wouldn't they start earlier? I think so, and I'm pretty sure that the studies of Lindauer and Seeley (among others) on labor allocating strongly support this view. If it's true, so the presence of young bees are truly beneficial in a no-brood colony.
Second, bees dye. And they not only dye, but they dye soon in the active season. Jim Fisher said recently that he works with the perspective of a lifespan between 45-60 days, but it sounds a little too optimistic. I checked some books, and found that Winston (Biology of the Honey Bee) talks about 38 days, Crane (Bees...) about 3.5-4 weeks, Caron (Honey Bee Biology and Beekeeping) about 4-5 weeks, and Morse (ABC & XYZ) about 4-6 weeks.
So, if you consider a developing period of 21 days, a fairly optimistic lifespan of 40 days, and a constant death rate (which is unreal), all the bees disappear in less than 9 weeks. It does not happen so quickly, in fact, because under such conditions not all bees become field bees, and those who keep doing house tasks get a longer lifespan. Anyway, it gives a good figure of how fast the population can decrease in the active season, when the colony is deprived of new eggs.
So, my point is that, for one side, young bees are important to honey production, for another, the colony probably shrinks very quickly when the queen is caged. So you will lose honey if you cage the queen (or remove one queen in a DQH) many weeks before the end of the flow. This idea only opposes the one presented by Michael, but doesn't answer the question I posed in item (2). Now, taking Moeller as another reference, (quoted by Crane in Bees..., and by Ambrose in The Hive and the Honey Bee), I read that he stated that four weeks BEFORE THE END of the flow is the right time to remove one queen in a DQC.
So far, I've presented only rhetoric and vague references, which sometimes are not very convincing (and often not even read), especially when written in a mistakefull English
. But maybe those bravehearts who had guts to read all of this will find it useful to take a look at a spreadsheet (MS Excel) I've just made, with a rough model of the colony development:
Colony model
There are two sheets, in fact. CDM1 has some periods highlighted with different colors, and commented. In CDM1, I used some parameters you may consider arguable, although I've tried to be realistic. Then I made CDM2, which is an unprotected sheet, where you can set the parameters as you like and get different results from the model. The sheets show the colony development by counting the daily increases in eggs laid, deaths, open brood, capped brood, nurse bees, and other [hive + field] bees. Nurse bees number is calculated according to Lindauer's estimation (quoted by Crane and Winston) of one nurse being capable of feeding 2-3 larvae (I took the average 2.5, so nurses = 40% open brood), but you may change that if you want. The model is very unreal in the start and in the end (colony with no bees), but I hope it gives a fairly good figure of what happens in between. Of course, it's a very simple model, based in averages and constant rates, and it was never intended to mirror the reality.
Well, since I have already written much more than the common sense would recommend, I think I won't do any worse in adding one more point:
(3) How much more honey can the beekeeper expect by caging the queen before the end of the flow?
I think, from what I've read from your posts and some books, that honey increase is mainly due to (a) extinction of the nurse tasks, freeing bees to participate in nectar gathering/processing, and (b) saving more honey because of no more need to feed the larvae.
Michael said:
> A large colony makes more honey.
> A large colony with no brood to
> care for will make twice that.
Would be "twice" a realistic figure?
Let's take a look at (a). How many bees are in fact freed by the extinction of the nurse job? At first thought, it may appear a lot. But, for a constant laying, the number of brood nurses tends to stabilize as the number of open brood stabilizes too, so nursing becomes a fixed cost for the the hive (and that's one reason why a large colony stores proportionally more honey than a small one). Qualitatively, you may reason that, when you cage the queen, the population is already at its peak, so the brood nurses are at the smallest possible percentage.
Quantitatively, it's sometimes difficult to visualize what really happens within such a dynamic group. But you can take a look at the model I pointed above. For the Lindauer's estimation, you'll find out that the percentage of bees in charge of brood in the peak of the season is only 5% of the total adults. So, probably no huge honey increases here.
Now, let's look at (b). From Winston (Biology...), we learn that a larva needs about 142 mg of honey and about the same weight of pollen to be reared. Assuming that the cost of gathering pollen is about the same of gathering nectar, I will consider that, roughly, each larva not reared saves about 300 mg of honey. I also assume that this is the total cost, including the pollen eaten by the nurses to produce food secretions, and the additional nectar spent in additional heating/fanning/water collecting due to the presence of the larvae.
If you take some 30 days as the useful period to produce honey with the queen caged, you'll get about 9 g of honey saved for each viable egg previously laid by the queen in each single day (in average). In other words,
Honey saved = 0.3 g x 30 days x ADL (average daily laying, in eggs/day)
If you consider ADL as 1,200 eggs, you'll get about 11 kg (24 lb) of honey saved. Or 13.5 kg (30 lb), for ADL = 1,500. Roughly, a shallow super in excess.
My conclusion is that one more supper of honey for each hive is indeed a very good result, although hardly a "double production", unless the flow/weather are very poor, or I'm grossly underestimating some aspect.
Just one more thing: since you don't know me, I'm afraid that this long post may appear to you as an arrogant flooding of data, intended to overwhelm and suffocate the discussion. Nothing is farther from the truth. I always appreciate your alert and critical posture. The long reasoning is only necessary for my own needs, because the topic is about a subject I'm not familiarized with - although general bee biology actually is a matter of interest to me. So, please (and I'm sure I wouldn't need to say this) feel completely free to point out the flaws and omissions in my ideas, references and calculations, so I can see it more clearly.
Best regards.
João