>Wouldn't you say this could be true with EHB's? Or in other words why don't
>the bees of Europe move down into africa?


Wide variety of possible reasons for that, but the most credible I have
come across is that EHB races are supposedly of an older type than the
central African types, and that scutellata is in all probability one of
the most recently evolved.

Its ways of converting energy give it a competitive advantage over
EHB's, but only within its normal latitudinally defined (reason unknown)
range. Outwith that its survival rate is lessened. Europe is well
outwith its range.

However, in low latitude areas where there is no AHB to outcompete it,
the EHB will do reasonably well, but in such areas where  AHB  is
already present they will fail to establish, hence no sustainable
natural incursions in Africa. The profile of pests they need to deal
with also differ in Africa and EHB is not adequately attuned to the
threats it meets. Not many army ants or honey badgers in Europe.

EHB races, assuming they are of considerable antiquity, have also become
very diverse with local selection pressures giving rise to local races
and sub races, and the comparatively restricted range of many types such
as iberica, cecropia, anatolica and a whole host of others underscores
this supposition. Such selection to meet regional needs inevitably means
that these qualities are unlikely to be the same for a relatively alien
environment, such as tropical Africa, hence, irrespective of age of
race, one type is not likely to be able long term to prevail in anothers
native range. The only exception to this is the new mutation possessing
a key advantage invading territory where it can get the better of the
extant stable local types.

In the Americas, despite assertions to the contrary, Apis mellifera is
not thought to have existed prior to its introduction by Europeans,
hence you have virgin territory in many ways and not all the races and
sub races patterns from the old world are present due to lack of both
sufficiently diverse imports and competition. Thus a reasonably adapted
bee to southern US conditions, usually ligustica, is relatively easily
supplanted by a better adapted beast, scutellata, and in the north it is
likely to be the reverse.

Potentially confusing subject, in which a whole heap more data is needed
before many reliable conclusions can be drawn. My belief though is that
the extent of invasion in South America has highly significant
implications for North America.

Murray
--
Murray McGregor