How many of you know what a supplemental mutant is?  Likely only one or two.  Or maybe none.  Supplementals are never covered in undergrad genetics to my knowledge.  They are very poorly understood.  They are also dirt common in multi gene traits.  They are so common it would surprise me if mite resistance did not involve some of them.  For the record a supplemental mutant is a mutant to which wild type is epistatic, but which will express in the presence of a specific second mutant only when that second mutant is homozygous.  They are so hard to sort out that most of the ones recognized and well understood are either pretty strong codominants or dominants in the presence of the homozygous second mutant.  However I have seen cases where they were recessives.  I have also seen cases of supplementals to supplementals.  Now, think about that situation for a while.  If you think combining such mutants is easy you are dreaming.  Supplementals are far harder to deal with than recessives.  There are only two breeding programs that have any chance at all.  You can use DNA directed mapping to pick breeders.  DNA directed mapping allows you to detect the presence of mutants without having the slightest clue what those mutants actually do other than move you in some desired direction.  If I were doing a breeding program on cattle, hogs, dogs or birds I would use such a program.  The problem is it is expensive.  You need to expect to spend hundreds of thousands of dollars in the lab every year doing DNA mapping.  But, when it comes to honey bees this is not very likely to work with today's technology due to issues with bee DNA.  Your only other choice is a classic breeding program where you pick some target you can measure such as identifying colonies that never show more than 5 mites per 300 bees over a 12 month period and breed from those.  In such a program you do not care how the bees get to their objective as such knowledge is useless in selecting breeders.  Actually, it is worse than useless.  The reason is the bees more than likely have several ways to get at least part way to that low mite count.  Some routes might get you 10% of the way and then you run into a wall.  Some might get you 30% of the way before you hit the wall.  You also have the issue that queens mate with lots of drones.  So some ways might give some encouraging results when the queen mates with one or two drones with the "right" genes but so overdo the behavior when she mates with 12 drones with those genes as to render the colony weak or worse.  If you think you are smarter than doing a classic breeding program and can measure for any of the above examples and select for it you will waste several years going down blind alleys for each one you try to follow.  And in the process of following it you will more than likely throw away other desired mutants setting the program back even more years as you try to recover after you hit the wall.  Every one of those paths you follow is likely to result in no real progress in someplace between five and ten years of breeding.  There simply is no reason to waste the time.  So, you are better off not even knowing of ways to measure any of the above examples.
Dick

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