Hi Mark
I think it is pretty clear the problem is not queens running out of sperm but of sperm quality. For example
> Cheshire computed the number of eggs which may be laid during her lifetime by a vigorous, fecundated honey-bee queen as about 1,500,000
but
> A fully inseminated queen carries approximately 5–7 million sperm (Woyke, 1989) from an average of 12 males (Tarpy and Nielsen, 2002).
I wrote in a recent issue of the American Bee Journal:
For me, the big question has been for some time: why is the rate of queen supersedure so high? In the literature you can read about queens living for five or six years. Many of us have seen three or four year old queens. And yet, the average life expectancy of a purchased queen appears to be about six months! What is going on here? Jeff Pettis, of the USDA, focussed on this issue. He described the extent of the problem: 50% queen loss in six months; queen replacement failure; high rate of drone laying queens.
When examined, it was discovered that drone laying queens had 62% dead sperm, despite the fact that the queens were well-mated (sufficient numbers of sperm). It was found that poor laying queens also showed a very poor rate of sperm viability: 50%. Meanwhile, good colonies with queens rated as “good layers” showed a 90% sperm viability. So, what could be causing drones to have sperm with such poor quality? The answer may surprise you: the chief suspect is beekeeper applied miticides. Applying miticides to drone producing colonies could result in drones with damaged sperm, leading to supersedure in colonies all over the country.
This possibility was further emphasized in the subsequent presentation by Juliana Rangel, from the North Carolina University at Raleigh. Juliana presented statistics which indicate that beekeepers attribute their losses to CCD at 9%, varroa at 24%, but queen failure at 31%, making it their worst problem. She pointed directly at the connection between miticides and sperm viability. In fact, her studies indicated that queens mated by drones with low quality sperm may actually increase the number of drones with which they mate to compensate.
Further studies of in hive effects showed that colonies treated with miticides thrived, building more comb and storing more honey. However, all the colonies superseded their queens in six months. In other words, the colony health may have been improved by the mite control measures, but the genetic makeup of the colony contributed by the queen would be lost due to replacement by the bees. This would be a serious problem for anyone attempting to create or maintain distinct honey bee stocks.
P
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