At 09:08 AM 8/14/2006, you wrote:
>I've always wondered about the claimed need to replace queens 
>annually...  Is this based on the claims of queen producers? ;o))

I'm assuming it's to maximize production and to reduce problems such as swarming, etc.

According to studies done by Sue Cobey (Columbus, OH)  she was seeing queens lasting 18 months (average) both for open mated and instrumentally inseminated queens in full production hives.  It seems their longevity is tied pretty closely to how much sperm they store and how many eggs they lay.  In small nucs they can last much longer as breeders in Europe have observed.

Naturally mated queens stored 3 to 6 million sperm, and II queens 4-5 million (possibly less than NM but more consistent)   We also know that queens actually release 5-10 sperm for each egg fertilized.  Now assuming an average of 1500 eggs a day for 6 months out of the year.  This means the queen could last 2.22 years before failing completely, though we do know they get pretty poor and often are superceded well before they run out of sperm completely. (30days/month * 6 months/year * 7.5 sperm/egg * 1500 eggs/day = 2.025mil/4.5mill=2.22 years) (Some assumptions are from http://gears.tucson.ars.ag.gov/beepop/life.html )

Now for queens worked year long this is little more than a year's worth of sperm (and just short of a  year's worth at 4million).

So it does seem to make sense to me and does seem to match the longevity observed (even the queen that's productive for 3 years with 6 million sperm).  Of course there are other factors at play (disease, etc.)  And I do wonder if some queens consistently have more muscle control and release fewer sperm than others (thus having a longer life).  Could this be something that can be selected for?

-Tim

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