Age and social experience induced plasticity across brain regions of the paper wasp Polistes fuscatus

Developmental studies of brain volumes can reveal which portions of neural
circuits are sensitive to environmental inputs. In social insects,
differences in relative investment across brain regions emerge as
behavioral repertoires change during ontogeny or as a result of
experience. Here, we test the effects of maturation and social experience
on morphological brain development in Polistes fuscatus paper wasps,
focusing on brain regions involved in visual and olfactory processing. We
find that mature wasps regardless of social experience have relatively
larger brains than newly emerged wasps and this difference is driven by
changes to mushroom body calyx and visual regions but not olfactory
processing neuropils. Notably, social wasps invest more in the anterior
optic tubercle (AOT), a visual glomerulus involved in color and object
processing in other taxa, relative to other visual integration centers the
mushroom body calyces compared with aged socially naïve wasps. Differences
in developmental plasticity between visual and olfactory neuropil volumes
is discussed in light of behavioral maturation in paper wasps, especially
as it relates to social recognition. Previous research has shown that P.
fuscatus need social experience to develop specialized visual processing
of faces, which is used to individually recognize conspecifics. The
present study suggests that the AOT is a candidate brain region that could
mediate facial processing in this species.