Fellow Beekeepers,
This has been a fascinating discussion.  Just a few comments.

Hybridizing of Brazilian/African/European bees over the years means their
genes are thoroughly mixed.  The discreet Cape bee has not been imported
into Arizona.  A hybrid, maybe.  Thelytoky does not mean the Cape bee with
all its characteristics is overtaking Tucson.

Thelytoky (the ability of a worker to lay fertile uninseminated eggs) is
only advantageous to a colony with the death of a queen, with no emergency
cells available.  If thelytoky were a raging success, there would be few
real queens in the social bee world, and lots of laying workers.  Or just
solitary bee species.

An interesting reference to the Cape bee problem is found at the web site
for Rupert's Honey, www.rupertshoney.co.za/rh/ .  Read under "Rupert's
Honey in the Press".  They contend that Cape bees that have drifted into a
hive to not "take over" as long as queen pheromone is strong, particularly
as bees cluster at night in the cold.  If a cluster forms away from the
queen, her pheromones do not influence the isolated cluster.  In this
condition, a "drifter" Cape bee will develop active ovaries and thelytoky
will ensue.  The take-home message for me if I were in S.Africa, is "don't
over-ventilate".  "Don't separate brood in the hive".  Don't allow
conditions that tend to make clusters isolated from the queen.

For those of you working with black bees in southern Arizona, you can do an
experiment to comfort us worrywarts.  Take some sealed brood, and move the
frame above the queen separator.  An isolated cluster will form.  The
thelytoky-prone workers may start egg production.  Check and see if there
are eggs and new brood above the queen separator.  This will prove
thelytoky in the presence of a queen.  That could be bad news to breeders.
If thelytoky is a real threat, the social order of the hive will break down
resulting in the failure of the colony.  This is a simple experiment, and
it will reveal the Truth that is Out There.

Cheers,
Kyle