The point that I found interesting in the paper was that it has been
commonly reported that African colonies  abscond if expose to too much
smoke.  The authors state that this is apparently not the case.  Thus, this
would refute the hypothesis that lack of defensiveness was due to
preparation to abscond.

In Visscher's paper that Pete cited, he did not arrive at any firm
conclusion as to the adaptive benefit of the nondefensive response to
smoke, and did not separate if from possible olfactory blocking:

"The presence of smoke may act on several of
the above responses at once, and may act at several
different stages. In species with chemical alarm
recruitment, it probably would interfere with the
perception of these signals, as it does in honey bees
(Visscher et al. 1995). It may serve as a repellent
which drives the insects deeper into the nest,
where they may be less Iike]y to perceive nest
disturbance stimuli, or where they may be less
effective at producing alarm recruitment stimuli
such as vibration of the nest envelope. Smoke may
affect the response which individuals exhibit to the
stimuli they perceive. In honey bees it seems to
have this effect at least in part indirectly, by
causing bees to engorge, and in turn to respond
differently."

The study that I cited suggests such an adaptive benefit, independent of
olfactory blocking.  A.m. capensis, yellowjacket wasps, and bumblebees all
share the common trait of often living below ground, and needing to deal
with wildfires.  Attempting to defend a hive against the disturbance of a
crackling fire by flying out to sting would be nonadaptive, since it would
be both futile and fatal.

On the other hand, going into a nondefensive retreat mode away from the
smoke would clearly be adaptive, as it would increase the probability of a
colony surviving the fire.  Thus, selection for this behavior.

-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

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