A Beekeeper's Diary

> I theorize that we can apply a similar approach to the virus problem
> associated with varroa and in this case the varroa themselves will do
> the culling - if we let them. By attempting to kill virtually all
> the varroa we remain on the treadmill; but if we use less effective
> treatments and tolerate a moderate (to be defined!) varroa
> population, then the most susceptible colonies will not survive. Of
> course, we do not want varroa levels to be so high that virtually all
> colonies die (because the US has huge pollination needs!), but should
> be able to cope with slightly higher losses if this leads to
> resistant bees.

This makes sense, but there are other considerations, too.

If -- and this is a big IF -- the beekeeper has commitment to a breeding program, and if that beekeeper has the resources -- money, time, education, discipline -- to follow through, then this can be a worthwhile avenue. However, for most of us, I suspect that completion of such a project is doubtful.

I know from experience that we may have big plans, and great expectations, but we often wind up buying replacement stock from a convenient supplier, moving, retiring, getting sick, losing interest, changing direction due to an opportunity... etc., etc. It happens more often than not. In such cases, little is accomplished in return for the effort and sacrifice.

Unless we are certain that we can -- and will -- persevere, we may be wiser to leave this selection and breeding to those who can and do -- and support their efforts by buying their stock in preference over others, and limit varroa populations in our own hives, however we can, to assure that we do not take needless and pointless losses.

Another thought: We know that the problem of virus transmission becomes a lethal problem when mite loads increase to where multiple foundress mites are found in more than the occasional cell.

AFAIK, varroa do not by choice enter cells already occupied by another foundress, and thus, we can deduce that these chance multiple infestations are likely to increase with mite populations (many seekers) and reducing brood area (fewer choices of cells).

We need to be particularly careful to maintain the ratio of varroa to brood below the level where frequent occurrences of multiple foundresses per cell become a statistical certainty.

The probability function (multiple foundresses/cell) rises much more rapidly than the mite/brood cell ratio, and explains why colonies tend to collapse suddenly as the varroa load increases and at the end of the summer when the brood rearing slows.

Anything we can do to avoid a high mite/brood ratio saves colonies.

Unless we are committed and capable breeders, failure to control varroa levels will not do us -- or anyone -- any good.

IMO, anyhow.

allen