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Informed Discussion of Beekeeping Issues and Bee Biology

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Subject:
From:
Peter Loring Borst <[log in to unmask]>
Reply To:
Informed Discussion of Beekeeping Issues and Bee Biology <[log in to unmask]>
Date:
Mon, 29 Jun 2015 07:26:26 -0400
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> Other than when robbing or drifting are involved, mite buildup follows an easily predictable trajectory, based upon varroa's intrinsic rate of reproduction when brood is present.

Based upon my observations in this area, robbing and drifting are always involved. This is why early season control measures usually fail to prevent high mite levels later. As early as 1998 this phenomenon was being studied:

> Our present results suggest that apiary isolation has the benefit of delaying the onset of economic thresholds; August colony mite levels were considerably lower in colonies in 1998 under conditions of isolation than they were in 1997 under conditions of mite immigration. -- Delaplane, K. S., & Hood, W. M. (1999). Economic threshold for Varroa jacobsoni Oud. in the southeastern USA. Apidologie, 30(5), 383-395.

This phenomenon has never really been analyzed in detail. No one knows exactly how this happens. All we have to go on are the effects. We have discussed this here at Bee-L in the past, and have noted that many parasites can induce their hosts to disperse. It is quite possible varroa does this as well, causing bees to leave their colonies and join other healthy colonies. 

PLB

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