Question #2 of Lars Hansen, who inquired (18 January):

"Correct me, if I am wrong:  It seems to me, that in experiments on
recruiting using odor (Wenner, Lindauer, Seeley ...), the concentration of
the smelling ingredient is very different?  It would be interesting to hear
comments on the concentrations.  Do some experiments disfavor the role of
odor by keeping the concentration low or others favor it by keeping them
high.  Is there such a thing as a realistic level of odor compared to
natural conditions?"

*******    Response (gladly provided):

   In 1937 von Frisch observed:  "[In my experiments] I succeeded with all
kinds of flowers with the exception of flowers without any scent."

   My co-workers and I reached the same conclusion by means of a rather
exhaustive series of experiments, published (in part) as a fully refereed
article:

1971  Wells, P.H. and A.M. Wenner.  The influence of food scent on behavior
of foraging honey bees.  PHYSIOLOGICAL ZOOLOGY.  44:191-209.

   Our 1990 book, ANATOMY OF A CONTROVERSY... also covers this topic quite
fully in Chapter 5 and in Excursus OS.

   However, one will not likely find a summary of the results of those
experiments in books and review chapters written by language advocates (the
results do not fit that favored hypothesis).  A few highlights follow:

1)  As experienced beekeepers know, bees are extremely sensitive to odor,
even if very faint.  For instance, an empty cavity that housed a colony
years earlier might well again become occupied.  That is why pest control
operators must clean out and thoroughly seal such cavities after removing
the colonies.

2)  By a fortunate circumstance, pure sugar solution (i.e., sucrose or
table sugar) has no odor, with its vapor pressure of zero.  However, one
must take extreme care in preparation of experimental sugar solution,
because any contaminant (in the solution or nearby) can provide an odor cue
for searching bees.  One must also take extreme care to not inadvertently
furnish any marking odor at experimental feeding stations in the field.

   James Nieh, formerly at Cornell, recently wrote (January issue of the
AMERICAN SCIENTIST):  "...foragers can successfully recruit (although with
greater difficulty) to a pure sucrose solution, which lacks an odor..."
However, I side with von Frisch on that issue and feel that Nieh perhaps
could not control against locality odors in his area, as we can do here
where we have no rain for months on end.

4)  Lars Hansen is quite correct; we do not know which odors can be
perceived by bees except through experiment.  In our 1971 paper we reported
that recruitment increased as one added more odor --- but only to a limit
(20 droplets of clove oil per liter).  A greater concentration led to a
severe drop in recruitment.

5)  The results shown in our 1971 paper are quite clear-cut:  a) Reduce
odor at the feeding station to zero, and Nasanov gland exposure by foragers
at the dish increases drastically.  b)  Reduce odor at the station to zero,
and dances by foragers in the hive increase dramatically.  c)  Reduce odor
at the station to zero, and searching bees do not find the site visited by
the foragers.

   Please note an important point here.  With no odor and with frequent
exposure of the Nasanov gland at the dish, searching bees STILL fail to
find the site.  That finding contrasts with another statement made by Nieh
in the AMERICAN SCIENTIST:  "In addition, a forager can mark good food
sources with a pheromone produced in her Nasanov gland."

***********

   Now to Lars Hansen's specific question:  "Do some experiments disfavor
the role of odor by keeping the concentration low or others favor it by
keeping them high?"

   My answer:  Certainly!  However, an experimenter can UNWITTINGLY or
SUBCONSCIOUSLY provide a discrepancy in odor marking at various feeding
stations.  Such an event, of course, would be more likely for one who
"wants" results that meet with favor by the scientific establishment. That
is why the multiple inference approach (where one does not care what
experimental results emerge) is so much more powerful than experiments
which attempt to "prove" that a bias is correct.  We covered such
experiments in Chapter 10 of our book, ANATOMY OF A CONTROVERSY.  Language
proponents, though, continue to ignore the results of those experiments.


**********

   A lesson here:  One must consider ALL available evidence, not just
evidence that agrees with prevailing opinion.

                                                                        Adrian

Adrian M. Wenner                    (805) 963-8508 (home phone)
967 Garcia Road                     (805) 893-8062  (UCSB FAX)
Santa Barbara, CA  93106

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*
*  "History teaches that having the whole world against you
*       doesn't necessarily mean you will lose."
*
*         Ashleigh Brilliant's Pot-Shot # 7521, used by permission
*
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