Problems with the Honeybee Dance Language Hypothesis

Julian O'Dea, Visiting Fellow, Division of Botany and Zoology, Australian
National University.


The "dance" of the honeybee (Apis mellifera L.) is one of the most famous of
all animal behaviours, but its meaning remains controversial.  On returning
to the hive after a successful foraging trip, a honeybee may do a "dance," a
set of movements that reflects in miniature the details of her trip. The
duration and orientation of the movements in the dance depend on the
distance from, and the direction of, the bee's latest foraging site relative
to the hive.  A longstanding debate centres on whether this "dance" is a
language, in the sense that it communicates this spatial information to
other bees, as famously proposed by Professor von Frisch.  An alternative
hypothesis is that locality odour alone, not dance movements, is the basis
of the communication of the whereabouts of resources (1).

An assumption of the classical von Frisch hypothesis has been that honeybees
are good at accurately estimating the distance they have travelled, so that
they can represent this in their dances for the information of other bees.
It has generally been thought that honeybees rely on the amount of energy
used on a trip to estimate the distance travelled (2, 3).

However "dance language" proponents recently obtained some unexpected
experimental results (4).  They found that the relationship between the
distance to resources and dance duration (which is supposed to reflect the
distance the bee has travelled) differed depending on the direction to the
food.  This suggested that the honeybees were not able to make absolute
measurements of distance travelled. Esch et al. (4) concluded that bees
actually measure distance from the amount of "optic flow" on their trip,
that is "the total amount of image motion en route to the food source".
Since the amount of optic flow differs depending on the visual features in
the honeybee's journey, this would explain why the bee's estimation of
distance might vary depending on the direction of her flight.  But, at the
same time, it implies that honeybees must be poor at measuring distance in
an absolute sense.

If Esch et al. (4) are correct, their findings raise problems for the "dance
language" hypothesis.  As they note themselves, the apparent lack of
absolute accuracy in the information about distance - supposedly conveyed in
the dance - is a problem for the proposed communicative mechanism. In the
absence of accurate distance information, as the authors write, " ... there
must be a high selection pressure to ensure that a dance signals the
direction of the food source as precisely as possible."  However there is
evidence that direction information is also not accurate (5).

The inaccuracy in the supposed means of communication makes it less likely
that the dance movements of honeybees have anything to do with communication
of the whereabouts of resources. The alternative, locality odour hypothesis
(1, 6) therefore gains in credibility.

Further evidence that bee species may show behaviours on returning from a
foraging trip that contain information about the trip that is not
communicated to the other bees in the hive comes from observations on
stingless bees (Meliponini) (6).  A study on Melipona quadrifasciata (7)
found that there was a correlation between the distance to resources and the
duration of the sounds emitted by foraging bees on their return.  However,
the study also showed that the distance information is probably not used by
the other bees in their foraging.  For example, although the bees were found
to respond to a sound signal that corresponded to a nearby feeding station
(0 to 30 m), "the bees did not respond to a signal for a feeding station 300
m away or for a station at any other distance".  The authors concluded that
" ... smell [locality odour] alone appeared to be a sufficient stimulus for
the trained bees to fly to the 300 m feeding station."

More recent studies (8-10) on another Melipona species, Melipona panamica,
also indicate that the bees make sounds on returning to the hive with
features that correlate with details of their foraging trips. The authors
propose that these sounds communicate the position of food localities to
other bees. However, little consideration was given to the possible
communication of the odour of food localities in providing information on
their whereabouts. No experiments were done that would have determined
whether the locality odour bees bring back from a desirable foraging site,
or the sounds emitted by bees on returning from the site, is the factor that
conveys information on the location of resources. It is quite conceivable
that - as in the case of Melipona quadrifasciata (7) - the sounds produced
by the bees that correlate with details of their foraging flights are not
the mode of communication.

In summary, it is conceivable that food locality odour is used by bees in
communicating the whereabouts of resources, not the supposed "dance
language" and other postulated forms of symbolic communication.  Dancing
movements and sounds emitted by bees returning from foraging trips may only
serve to attract the attention of hivemates so that they can be made aware
of the odours associated with desirable food sites (6).


References:


(1)     Wenner, A.M. 1971.  The bee language controversy: an experience in
science.  Educational Programs Improvement Corporation, Boulder, Colorado,
USA, 109 p.

(2)     Goncalves, L.S.  1969.  A study of orientation information given by
one trained bee by dancing.  J. apic. res.  8 (3): 113-132.

(3)     Michener, C.D.  1974.  The social behavior of the bees: a
comparative study. Harvard University Press, Cambridge, USA, 404 p.

(4)     Esch, H.E., S. Zhang, M.V. Srinivasan and J. Tautz.  2001.  Honeybee
dances communicate distances measured by optic flow.  Nature 411: 581-583.

(5)     Vadas, R.L. 1994.  The anatomy of an ecological controversy:
honey-bee searching behaviour.  Oikos 69: 158-166 and at:
http://www.beesource.com/pov/wenner/oikos94.htm

(6)     O'Dea, J.D. 2000.  Why do honeybees dance?  naturalSCIENCE
http://naturalscience.com/ns/nshome.html

(7)     Esch, H, I.Esch and W.E. Kerr.  1965.   Sound: An element common to
communication of stingless bees and to dances of the honey bee.   Science
149: 320-321.

(8)     Nieh, J.C.  1998   The role of a scent beacon in the communication
of food location by the stingless bee, Melipona panamica.  Behav. Ecol.
Sociobiol.  43:  47-58.

(9)     Nieh, J.C.  1998.  The food recruitment dance of the stingless bee,
Melipona panamica.   Behav. Ecol. Sociobiol.  43: 133-145.

(10)    Nieh, J.C. and D.W. Roubik.  1998.  Possible mechanisms for the
communication of height and distance by a stingless bee, Melipona panamica.
Behav. Ecol.  Sociobiol.  43:  387-399.