Dear All

I have followed these two discussion points with interest over the past
two weeks, but have refrained from commenting because I have
previously posted to the List on both issues. But in terms of the current
discussion, perhaps some thoughts and comments bear repeating; and
also there is new information and possibilities.

The "Capensis in Arizona" Situation:

(1) Queenless worker Cape bees, historically present in only the
Western Cape of South Africa, produce by thelytokous
parthenogenesis and hence produce female offspring (workers or
queens). This is probably evident is all pure Cape workers, but it is
possible that some may produce drone offspring or no offspring at all.

(2) Cape honeybees have some other unique characteristics: (a)
workers have large numbers of ovarioles (average 12); (b) very large
spermatheca; (c) ability to develop queen-like chemical signals very
rapidly in the absence of a queen; (d) Cape workers are treated in a
queen-like fashion by workers of other races, both as larvae (more
feeding) and as adults; (e) Cape workers are not controlled (inhibited)
by queens of other races.

(3) Hence, when capensis workers get into colonies of other races,
problems occur. The capensis workers develop chemically and
physiologically; produce more capensis workers; and result in the loss
of the queen. These colonies become capensis laying worker colonies,
and normally dwindle to a few hundred bees, which may then invade
other colonies, repeating the cycle. Capensis laying worker problems
have been seen previously in Germany, Brazil, Zimbabwe and South
Africa (at least 3 times). All of these, except the last event in South
Africa, have dissipated or been controlled.

(4) The last event in South Africa, the Capensis Problem, started in
about 1990, effects almost all of non-capensis South Africa, and
continues to this day. Hundreds of thousands of scutellata colonies
have been lost, and as yet no solution is in sight. There are no
indications of scutellata colonies resistant to the capensis takeover, but
the problem is one only of commercial beekeeping, and the wild
population is essential pure scutellata (and is not threatened by the
Capensis Problem).

(5) There are various speculative reasons as to why this capensis
event has become such a huge problem, while others have not - but
this remains largely speculation at this stage, and should not be part of
this discussion.

(6) In 1943 Mackensen published an account on research done on 3
"lines" of bees in the USA, which indicated that 1% of workers in these
lines produced female offspring (assumed by thelytoky). This led to the
general conclusion that thelytoky was present in all bee races of the
world at a low level (1%) but was found in all Cape bees.

(7) To the best of my knowledge, there is only one piece of supporting
evidence for Mackensen's contention, and what is now conventional
wisdom. And that is the report from Ericksen (about 1992) on the
Lusby bees, that reported thelytoky in this population. This "line" of
bees was then reported to have "disappeared" but is now again the
centre of the reports of thelytokous bees from Arizona.

(8) As far as I am aware, the only "capensis" trait being reported from
the Arizona bees is that some of the workers produce female offspring,
presumably by thelytoky. There is no report of them causing queen
loss, dwindling in colonies, invasion of colonies or colony loss.

(9) This situation is of both academic and economic importance, and is
being investigated, as follows: (a) confirmation of the thelytokous
reproduction of these workers; (b) investigation of these thelytokous
bees to see if they are indeed capensis, or have other other capensis
traits {this will involve looking at things like ovariole numbers and
spermatheca, as well as DNA analysis (which is a great deal more
difficult than it sounds, as capensis and scutellata are very similar
genetically); (c) investigation as to whether any of the deleterious traits
(invasiveness, queen loss, dwindling) occur with these thelytokous
bees.

(10) The results of which will indicate whether: (a) this is a non-
capensis thelytokous population (of academic importance); (b) is a
thelytokous but non-destructive capensis-type (which may be of value
in the South African situation); or (c) is a thelytokous and destructive
capensis-type, which should be of great concern to the USA.

Small Cell Size and Varroa:

(1) The natural cell size for African bees (capensis and scutellata) is
4.8 - 4.9 mm.

(2) Varroa populations in colonies of both capensis and scutellata
increased to enormous numbers (>5000) soon after the arrival of the
mite.

(3) Martin and Kryger (2001) report similar successful reproduction in
scutellata worker cells to that found in European bees (with larger
cells). I have found the same in worker cells of Cape bees.

(4) These results clearly demonstrate that the smaller cell size, per se,
of African bees does not limit the reproduction of varroa.

(5) However, we are starting to see that, in an unmanaged population
of Cape bees, varroa numbers have dramatically declined. Please note
that .70% of this population has died since the beginning of monitoring,
and the decline is in the survivors. Please note also that these results
are preliminary, and far from conclusive.

(6) The decline in varroa numbers in these colonies MAY be related to
the high percentages of infertile (probably unmated) female mites
found in the colonies; and these infertile females MAY be related to the
SMR situation in the USA or MAY be related to something else, such
as the small cell size. Martin & Kryger (2001) report increased mite
mortality if African workers in cells are larger than normal.

(7) In summary, I suggest that what we may be seeing is that the
survivors of unmanaged African bee populations may be dealing with
the mite. The reasons for this mite tolerance are yet to be determined,
but small cell size may be a factor. I think that it is likely, however, that
a number of factors will be involved.

(8) I respectively suggest that something similar has occurred in the
Lusby bees, and that simply enforcing the small cell size on OTHER
BEES in the USA is unlikely to result in the same situation.

I hope the above has contributed to the debate.

regards

Mike Allsopp
Stellenbosch, South Africa