Stealth Bees!

Why are African bees so successful at invading and taking over in the new
areas they have encountered as they have moved from Brazil, through Central
America, and finally to the US? There is no doubt that there are many
mechanisms responsible for this, but one of the most interesting is their
propensity to "take over" colonies of less aggressive European bees. 

Research shows how they may do this using small "stealth bees" that have
characteristics of both queens and workers. This was already seen in Africa
among Cape Bees, and we now know that other African types, such as
scutellata, have this trait. 

Apparently, these bees sneak into colonies and attempt to kill the resident
queen. Being smaller than regular queens no doubt gives them many
advantages. They are faster, and are more easily overlooked by the guards.
Yet they have queen-like qualities also, which many enable them to suppress
queen production by the victim colony. 

References:

While most female honey bees are exclusively workers or queens, we found
bees with characteristics of both workers and queens in African honey bee,
Apis mellifera scutellata colonies, African usurpation swarms and in
colonies of European honey bees, Apis mellifera, in the southwestern United
States.

We call these females intermorphs. Intermorphs resemble workers in body size
and the shape of their head and mandibles. However, intermorphs are
queen-like in the shape of their thorax and abdomen, and in the distribution
of hairs on their body. The most interesting feature about intermorphs is
that the volatile compounds (i.e., odors) they emit are similar to those of
a queen. We speculate on how intermorphs might influence worker-queen
interactions and possibly influence the invasion of European honey bee
colonies by African bees. 

Because IMs emit many of the same volatiles as a queen, it is possible that
the presence of IMs in a colony might confuse chemical signals emanating
from the queen that advertise her presence. A possible case in point is that
we regularly saw IMs in usurpation swarms of African bees. The volatiles
from IMs might be used for aggregation by workers. IMs also might play a
role in affecting the chances of a swarm queen entering and establishing
herself in an invaded colony. Thus, IMs might contribute to the success
African bees have had in invading European habitats.  -- GLORIA
DEGRANDI-HOFFMAN, et al

* * *

Worker bees of the Cape honeybee, Apis mellifera capensis, show the
anarchistic trait but to an extreme degree. They can develop into so called
"pseudoqueens", which release a pheromonal bouquet very similar to that of
queens. Lethal fights between these parasitic workers and the queen (similar
to queen–queen fights) occur, resulting in the death of either queen or
worker. Although it is usually the queen that attacks the parasitic workers
and kills many of them, in a few cases the workers succeeded in killing the
queen. If this also occurs in a parasitized colony where the queen
encounters many parasitic workers, she may eventually be killed in one of
the repeated fights she engages in. -- Robin F. A. Moritz, et al

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