In: Chemistry and Biology of Social Insects, Proc. X Internatl. Congr. IUSSI
Munich.
(ed. J. Eder & H. Rembold), Munich: Verlag J. Peperny. (1987).
EvolutionofInsectSocieties
377
""
Social Structure and the Determinants of Queen Status
in the Primitively Eusocial Wasp Ropalidia cyathiformis
RaghavendraGadagkar
Centrefor Ecological Sciences,
IndianInstitute of Science,
Bangalore-560 012,India
.Primitively
eusocial wasps are of great'interest to students of sociobiology because of the flexibility in social roles that an individual can
adopt. This flexibility
can be rather spectacularly illustrated using the
common Indian spe.cies Ropalidia cyathiformis (Gadagkar and Joshi 1985).
Here females eclosing on a nest have several options open to them. Some
females leave the parent nest to start new, baplometric nests. Others
also leave to found new nests, but pleometrotically i.e., they leave along
with some workers.
Yet other females stay on at the parent nest and
eventually challenge the queen and take over the nest. Finally of course
some females stay on at the parent nest and remain as sterile workers
t~roughout t.heir life.
Prompted by the presence of such diverse reproductive strategies we have made a quantitative study of the behaviour of
individually identified wasps. Even among the females staying back at
the parent nest, multivariate statistical analysis of time activity budgets
of individually identified wasps has -revealed the presence of a behavioural
caste differentiation
into Sitters, Fighters and Foragers (Gadagkar and
Joshi 1984). Here I report experiments designed to understand the biological and evolutionary significance of tryese behavioural castes.
MATERIALS AND METHODS
Naturally initiated post emergence colonies of R.cyathiformis were
studied on the grounds of the Indian Institute of Science, Bangalore. Wasps
were individually marked wi th spots of coloured paint, behavioural data
were collected us:ng unbiased sampling methods and multivariate and other
kirlds of data analysis were performed on a DEC 1090 Computer, all as
described previously (Gadagkar and Joshi 1984).
After sufficient data
on a colony were collected, its queen was removed and the observations
repeated.
RESUL TS AND DISCUSSION
All the colonies studied showed a behavioural caste differentiation
into Sitters, Fighters and Foragers both before and after the queens were
removed.
A typical pattern is illustrated in Fig.l.
In conformity with
previous results and in contrast to a related species R.mar.ltinat~ (Gadagkar
and Joshi 1983), the queens of all the colonies were Fighters. In 7 out
of 8 cases of removal or disappearance of a queen one of thE' subordinates
iis5umed the role of a queen and began to lay eggs within about a week
of queen removal.
In every case the potential queen (the wasp that succeeds a removed queen) was a Fighter. As seen from Fig.l the potential
queen was remarkably different from all the other wasps in the colony
and remarkably similar to the queen in her behavioural profile.
In many
cases the behavioural profile of that wasp who would eventually succeed
the potential queen when the latter was in turn removed could be studied.
Such a wasp is termed potential queen 2. The potential
queen 2 was
always a Sitter but not different from any other wasps in any discernable
manner.
Eder/Rembold,Chemistryand Biology ofSocial Insects,VerlagJ. Pepemy,Mlllichen 1987
c
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378
Evolution ofInsect Societies
(I.ng."'"
Ropalidia cyathiformis Colony P 2 (OI("'2. J.n"8'1
SITTERS
.0
-.
-.
UJ
I-z
(
@
::=~~~~:~.
."
.. co'
~
.
.
.'.
a. .04
.
'.
:
~
0
U
~
FORAGERS
~
.02
a
a.
6
PRINCIPAL
Fig.l.-Behavioural
formis
profiles
colony
by
time-activity
was
removed)
gers
The
is
4
of
these
four
of
rank
in
6
out
in
6
out
more
of
often
than
to
ranking
but
the
Meyer
reasonable
fixed
even
a
colony
of
an
to
in
active
striking
high
potential
queens
appear
to
nest
food
where
colonies
the
the
brought
are
be
predicted
role
with
to
at
domi-
behaviour
food
results
known
be
present
exclamans
most
can
inspite
highest
had
these
all
The
dominance
Polistes
in
respec~ive
the
females
of
as
summary
The
healthy
Fora-
and
females
of
are
who
and
their
brought
other
Some
certainity.
in
case
such
In
queen
queen
principal
queens
in
had
never
Foragers
1983).
two
available.
the
frequency
queen.
repre-
the
known
females
queens
oldest
potential
with
be
the
were
queens
highest
wasps
first
animal
Among
7th
after
removed
older
potential
the
potential
of
defined
queen
in
zone
some
and
well
and
temperate
(Strassmann
to
cases
6
potential
.~.cyathi-
Fighters
oldest
removal.
the
The
the
animals
Jbe
succeeded
the
shown
cases.
7
queen
of
or
Sitters,
the
not
and
a
pornt
centroid.
of
1
in
Each
before
clusters,
discussion
10,
removal
had
7
3
nearest
was
7,
of
(either
space
ages
under
time
wasp
the
of
the
:wasps
analysIs.
co-ordinate
queen
queen
and
of
contrast
cases
present
the
time
nance
7
a
of
potential
being
at
the
the
method
queens
there
colonies
the
the
the
potential
of
by
identified
components
of
distinctness
confirmed
In
of
in
I
individually
principal
budget
plotted
components.
a
of
analysed
~the
COMPONENT
to
become
potential
have
the
queen
next
appears
queen.
REFERENCES
Gadagkar,
R.,
Joshi,
N.
Time
activity
(Lep.)
(Hymenoptera:Vespidae).
Gadagkar,
R.,
Joshi,
Ropalidi~
64,
Gadagkar,
Strassman-n:;Polistes
(1983).
and
Quantative
Caste
Ethology
differentiation
(1984).
(Fab.)
ll,
Social
of
in
Anim.Behav.,
N.V.
cyathiformis
Social
Rop~lidia
Wasps:
marRinata
26-31.
Organisation
in
the
(Hymenoptera:Vespidae).
Indian
Z.
Wasp
Tierpsychol.,
15-32.
R.,
Sci.,
budgets
V.
54,
Joshi,
N.V.
(1985).
Colony
Fission
in
a
Social
Wasp.
Curro
57-62.
J.E.,
exclaman~.
Meyer,
D.C.
Anim.Behav.,
(1983).
Gerontocracy
ll,
431-438.
in
the
Social
Wasp