>When more than one mite invade a single brood cell, the per capita fecundity decreases, as the number of mother mites per cell increases. Mites invading brood cells in older combs also have fewer offspring. This led scientists to speculate that mites themselves might have a chemical to inhibit each other’s reproduction (a pheromone).

I was surprised that this did not get more reaction from the list.

That old comb may be significantly inhibiting varroa population growth is something that I have not read before.  It could explain why feral colonies and beekeepers who do not change combs regularly (I have to declare an interest here!) have less problems with mites.

It also suggests to me that it raises control issues for experiments.  How many researchers ensure that all their colonies have comb of the same age and have had the same number of mites breed in them?

Best wishes

Peter 
52°14'44.44"N, 1°50'35"W

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