Abstract

The left and right antennae of stingless bees have different roles in learning
and recall of olfactory memory. Antennal asymmetry in social behavior is reported
here. Approaches and physical contacts were scored in dyads of stingless bees
(Tetragonula carbonaria): dyads in which both bees had only their right antennae (left
antennae removed) made significantly more physical contacts with each other than
dyads in which both bees had only their left antennae. In dyads of one left and one
right, it was found, unexpectedly, that the bee with a left antenna approached the bee
with the right antenna more often that the other way around, and the bee with the left
antenna often attacked (by biting) its hive mate. Hence, the low number of contacts in
dyads of bees using their left antennae appears to be due to mutual avoidance. Whereas
use of the right antenna stimulates positive contact, the left stimulates avoidance or
attack. Via such left-right asymmetries, intact bees may compute behavior directed
towards friend and foe. Such antennal asymmetry may have evolved concomitantly
with eusocial behavior. We found no evidence that it was associated with
significant differences in the number of olfactory or non-olfactory sensilla on the
left versus right antenna.