The population of Africanized bees that produced the dramatic expansion 
of their range out of Brazil "escaped" interacting with varroa.  The 
range expansion into northern South America occurred in the mid to late 
70s and into the early 80s and did not "carry" varroa.  Varroa was 
first detected in Brazil in 1982.  So while Brazilian AHBs were 
confronted with varroa in the 80s, the AHBs of northern South America, 
Central America and Mexico did not face varroa until later, likely 
through point introductions and more into the 90s.  This may explain 
why there is more evidence for resistance in Brazil (although a bit 
murky through different regions and through time) than in the rest of 
Latin America, and even in the US. 

To my knowledge no one has demonstrated the existence of a unique, 
strong and fixed resistance/defense mechanism or tolerance in any 
population of AHB.  This would be the first step in any consideration 
of possible use in breeding programs.  And the second part of the 
decision to use AHB is whether it is worth the effort of separating out 
any unique trait from the undesirable traits in the package that 
usually comes with most AHBs.  

 

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