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From:
Peter L Borst <[log in to unmask]>
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Informed Discussion of Beekeeping Issues and Bee Biology <[log in to unmask]>
Date:
Sun, 30 Nov 2008 08:48:14 -0500
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Juanse writes
> It is pity that in Chile we do not have scutellata, and that our authorities do not want it here, other wise I will import Dee's Bees.

Might work, Juanse. They sure do seem to have the right stuff!

> The only genetic line of A. mellifera which has consistently been found to be resistant to V. destructor is the Africanized honeybee (AHB). Mite resistance was first observed in Brazil and the low level of mite fertility was considered to be the reason. Three independent studies carried out in different tropical regions of Mexico showed that AHB colonies were able to survive without the application of any mite control measures, while the mite population cycled between 1000–8000 mites. In sharp contrast, European honeybee (EHB) colonies kept in the same region, died within a year because of the rapidly increasing mite population.

"Mortality of mite offspring: a major component of Varroa destructor
resistance in a population of Africanized bees" by Luis MONDRAGÓN,
Stephen MARTIN, Rémy VANDAME Apidologie 37 (2006) 67–74

> Although the mite has caused severe losses of honeybee colonies and has eliminated wild bee populations in temperate climates, it does not appear to be a serious pest in regions of the world where the Africanized honey bees (AHB) exist. Low infestation levels of V. destructor in AHB have been reported and different mechanisms of resistance of the bees to the mite have been described. On its original host, the Asian bee A. cerana Fabr., the mite is not a serious pest, because it does not reproduce successfully on worker brood. Consequently the total number of V. destructor within an A. cerana colony is always low (< 800). In AHB colonies, the mite can reproduce in worker brood cells, which are more abundant than drone brood cells, and V. destructor populations stabilize between 1000–3000 mites without killing the colonies. In European honeybees (EHB), the mite populations are able to increase 4-fold annually in tropical regions, causing colony death within one year because as few as 2000– 3600 mites are enough to kill an EHB colony according to a model approached by Martin (2001) for honeybees from Europe.

"A multifactorial study of the resistance of honeybees Apis mellifera
to the mite Varroa destructor over one year in Mexico" by Luis
Mondragón, Marla Spivak and Rémy Vandame, Apidologie 36 (2005) 345-358

* Here Remy Vandame makes the case that European bees have been
mollycoddled while Africans have always had to fight for survival:

> The main challenge for survival of European subspecies has been the climate. For the African subspecies it has been the confrontation with predators and parasites; to date, 160 mite species are known to be associated with tropical honey bees. The defense against predators has been an increase in aggressiveness, and the main defense against brood parasitism could well be the removal behavior. Thus we can hypothesize that the removal behavior reported in the present paper for AHB mainly constitutes a trait acquired by African bees during their evolution, prior to their encounter with V. destructor.

> Another speculation could be that European and US commercial honey bee populations (those that have been protected by man from dying from V. destructor) arose from human selection over centuries. Factors selected include low defensiveness, low level of nestmate discrimination and, maybe as a side effect, lower resistance against parasitism. Thus, we hypothesize here that the bees usually classified as European are mainly derived from anthropogenical selection. They are actually gentle, but also form compatible associations with parasites like V. destructor. On the contrary, feral bees, when they still exist, though less gentle, would still have intact resistance abilities.

"Parasitism in the social bee Apis mellifera: quantifying costs and
benefits of behavioral resistance to Varroa destructor mites" -- Remy
VANDAME, et al, Apidologie 33 (2002) 433–445

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