> We can use simple biology and arithmetic to estimate the effect of an induced brood break on the varroa population of a hive.  Let's say that you are inducing the brood break early in the season--say on the 1st of April.


Maybe I'm reading too much into the choice of words but I think I'm missing something in the math.

For an induced brood break on April 1 and assuming the 20 day break, the new queen will start laying on April 21.  Since they will be eggs for 3 days and larvae for another 6, the new brood will be capped on about May 1 with the first new workers starting to emerge on May 13th and drones on the 16th.

Where I struggle to match the math is when I consider the tail of brood that still remain in the colony at the point that we killed the old queen.  Assuming steady-state, her brood will continue to be capped off until April 10.  They will continue to emerge until April 22 for workers and April 25 for drones.  A 20 day gap in egg-laying does not directly lead to a 20 day gap in mite reproduction.

Where I really get lost is in how much smaller that gap should be.  Does that measured r value of 0.015 count the mites' growth as if it were all at the point of emergence or does that measure assume that the reproduction continues within the capped pupae period?  Depending on the answer, it seems to me that a 20 day egg-laying break leads to a mite-reproduction break of somewhere between 5 and 17 days.

And while that's still a gap that will affect mite populations measurably, the exponential nature of the equations suggests that the difference should be significant.

I further confuse myself when I ask whether the model should try to accommodate the non-linearity in parasitizable brood during the transition period between queens.  For example, during the drone-only period, there are fewer brood but do the mites "adjust" by parasitizing them more heavily?  Would that affect the assumed r values?  If so, by how much?

Like most good models, the brood-break model seems to raise as many questions as it answers.  Or am I missing something obvious? Mike Rossander


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