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In the ectatommine ant Ectatomma tuberculatum, the visual appearance of queens changes after mating and ovarian development in that their cuticle turns from shiny to matte. In this study, we have shown that this change seems to be caused by 15-fold accumulation of hydrocarbons, in particular heptacosane that covers the multiple grooves present on the cuticular surface creating a wax coat in mated fully fertile queens. Analyses of the scrapped wax revealed that it is composed largely of heptacosane. Peak-by-peak comparison of the cuticular hydrocarbon (CHC) composition of mated, virgin with developed ovaries and virgin with nondeveloped ovaries revealed significant differences between the queen groups. Although the total amount of the CHC of virgin queens with developed ovaries was not higher than virgin queens that did not have developed ovaries, the composition showed a shift toward the mated queen. While it is possible that the large accumulation of hydrocarbons may give extra physical and chemical protection to queens, we propose that the switch in the relative abundance of heptacosane and nonacosane and perhaps of other components is indicative of being a mating and fertility cue. This is the first report in social insects where external chemical changes are accompanied by changes in visual appearance.
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SHORT COMMUNICATION
Postmating changes in cuticular chemistry and visual
appearance in Ectatomma tuberculatum queens
(Formicidae: Ectatomminae)
Riviane R. Hora &Armin Ionescu-Hirsh &Tovit Simon &
Jacques Delabie &Jacques Robert &
Dominique Fresneau &Abraham Hefetz
Received: 15 October 2004 /Revised: 30 June 2007 / Accepted: 30 June 2007 / Published online: 28 August 2007
#Springer-Verlag 2007
Abstract In the ectatommine ant Ectatomma tuberculatum,
the visual appearance of queens changes after mating and
ovarian development in that their cuticle turns from shiny to
matte. In this study, we have shown that this change seems
to be caused by 15-fold accumulation of hydrocarbons, in
particular heptacosane that covers the multiple grooves
present on the cuticular surface creating a wax coat in
mated fully fertile queens. Analyses of the scrapped wax
revealed that it is composed largely of heptacosane. Peak-
by-peak comparison of the cuticular hydrocarbon (CHC)
composition of mated, virgin with developed ovaries and
virgin with nondeveloped ovaries revealed significant
differences between the queen groups. Although the total
amount of the CHC of virgin queens with developed
ovaries was not higher than virgin queens that did not have
developed ovaries, the composition showed a shift toward
the mated queen. While it is possible that the large
accumulation of hydrocarbons may give extra physical
and chemical protection to queens, we propose that the
switch in the relative abundance of heptacosane and
nonacosane and perhaps of other components is indicative
of being a mating and fertility cue. This is the first report in
social insects where external chemical changes are accom-
panied by changes in visual appearance.
Keywords Cuticular hydrocarbons .Fertility cue .
Wax coat .Ant
Introduction
The relationship between reproduction and social status is
well expressed in social insects with a reproductive division
of labor (Bourke and Franks 1995; Crozier and Pamilo
1996), where reproduction is strongly biased toward
queens. Reproductive skew in these societies may be
attributed to differences in caste development but also
through regulatory measures imposed by the queen that
influences worker reproductive potential (Fletcher and Ross
1985). Reproductive dominance is generally conveyed by
chemical cues, which are considered as reliable signals
because they act consistently with queen presence and her
reproductive status, allowing workers to correctly assess
queen fertility (Keller and Nonacs 1993).
Naturwissenschaften (2008) 95:5560
DOI 10.1007/s00114-007-0287-2
R. R. Hora :D. Fresneau
Laboratoire dEthologie Expérimentale et Comparée
(CNRS UMR 7153), Université Paris 13,
99 Avenue J.-B. Clément,
93430 Villetaneuse, France
A. Ionescu-Hirsh :T. Simon :A. Hefetz
Department of Zoology, George S. Wise Faculty of Life Sciences,
Tel Aviv University,
Ramat Aviv 69978, Israel
J. Delabie
U.P.A. Laboratório de Mirmecologia, Convênio UESC/CEPLAC,
Centro de Pesquisas do Cacau,
C.P.7, 45600-000 Itabuna, Bahia, Brazil
J. Robert
Laboratoire de Physique des Lasers, (CNRS UMR no. 7538),
Université Paris 13,
99 Avenue J.-B. Clément,
93430 Villetaneuse, France
Present address:
R. R. Hora (*)
U.P.A. Laboratório de Mirmecologia, Convênio UESC/CEPLAC,
Centro de Pesquisas do Cacau,
C.P.7, 45600-000 Itabuna, Bahia, Brazil
e-mail: rivianer@hotmail.com
Several studies have suggested that cuticular hydro-
carbons (CHCs) may act as reliable signals in denoting
ovarian status of the queen (Liebig et al. 2000; Tentschert et
al. 2002; Dietemann et al. 2003) or gamergates in queenless
ants (Peeters et al. 1999; Cuvillier-Hot et al. 2001). In
Formica fusca, differences in egg production by the
multiple queens are reflected as differences in CHC profiles
(Hannonen et al. 2002), providing workers with cues for
assessing queen fertility. Direct evidences of the function of
the CHCs as a reliable signal of fertility has been recently
demonstrated in the myrmeciine ant Myrmecia gulosa
(Dietemann et al. 2003) and in the ponerine Pachycondyla
inversa (DEttorre et al. 2004). Using electroantennogra-
phy, DEttorre et al. 2004 established that the putative
fertility signal 3,11-dimethylheptacosane in P.inversa is
perceived and recognized by workers.
In this study, we explored the effects of mating and
ovarian development on the CHC profiles of Ectatomma
tuberculatum queens, a facultative polygynous ant distrib-
uted throughout the Neotropics (Hora et al. 2005). Queens
of this species exhibit conspicuous visual differences where
virgin queens possess a shiny cuticle, whereas the cuticle of
mated queens is matte. In this study, we examined if such
phenomenon is correlated to differences in CHC profiles.
Materials and methods
Large established colonies (n=8) of E.tuberculatum were
collected in 1999 and 2001 at Itabuna, Bahia State, Brazil.
A total of 37 females, 22 with matte cuticle and 15 with
shiny cuticle, were analyzed for their reproductive status
and CHC profiles. Six out of 15 shiny females emerged in
the laboratory in 2001 (from colonies collected in 1999);
the other shiny queens were collected in the field in 2001,
including one female that lived in the laboratory for 2 years
before being killed for the analysis.
The females were dissected in a Ringers solution under
a stereomicroscope for assessing their mating status (full or
1a 2a
1b 2b
1c 2c
Fig. 1 The cuticle of shiny
(series 1,top to bottom) and of
matte (series 2,top to bottom)
queens of E. tuberculatum. The
top pictures depict the total
appearance of the queens, while
the following are enlargements
of the surface revealed by SEM.
The white arrow in series 2 b,c
shows a part of cuticle from
which the wax was delicately
scrapped off with forceps
56 Naturwissenschaften (2008) 95:5560
empty spermatheca), total number of ovarioles and of yolky
oocytes, and the presence of yellow bodies that indicate
previous egg laying. The differences in cuticular surface
structures between queens were investigated by scanning
electron microscopy (SEM; Leica Stereoscan 440 at
10 kV). One-millimeter fragments of the head, thorax, and
abdomen cuticular surfaces of both matte and shiny queens
were scanned without metallization to preserve the natural
coating of cuticular fragments.
For chemical analyses, queens were killed by freezing, and
thoraces were immersed in 1 ml pentane for extraction.
Cuticular wax from matte queens was scraped off and was
extracted immediately in pentane. Identification of CHC was
performed by gas chromatography (GC)/mass spectroscopy
(VGM250Q) using a DB-5 fused silica capillary column
(Temperature program: 120270°C at 5°C/min, hold at 270°C
for 30 min, and then heated to 295°C at 20°C/min). The
eluting CHCs were identified by their fragmentation pattern.
Quantifications were achieved by peak integration using the
same GC conditions, adding heptadecane as an internal
standard.
Peak-by-peak comparison was performed for three
groups: mated queens (n=22), virgin queens with devel-
oped ovaries (>2 yolky oocytes, n= 5), and virgin queens
with nondeveloped ovaries (n=18). Comparisons were
made using the arcsin-transformed peak relative intensity
and a one-way analysis of variance, followed by post-hoc
Tukey tests. All data are presented as mean±SE.
Results
Inspection of the spermatheca of 37 queens revealed that all
22 matte queens were inseminated, whereas all 15 shiny
queens were virgin. The total number of ovarioles ranged
from 20 to 28 (mean±SD= 24.46 ± 1.74), but mated-matte
queens had higher numbers of yolky oocytes (37.35 ± 16.61;
range=775) in comparison to virgin-shiny ones (3.57 ±
2.51; range=18; n=7). Eight virgin queens, including four
shiny ones that emerged in the laboratory, did not have
yolky oocytes at all. All mated queens had a large number
of conspicuous dark yellow bodies, indicating high levels
of egg laying. In contrast, six shiny queens had only slight
yellow bodies indicating reduced egg laying of male-
destined and/or trophic eggs.
The SEM examination (Fig. 1) confirmed that the
cuticle of virgin queens has multiple grooves and rims that
highly reflect light and give it its shiny appearance (Fig. 1;
series 1, AC), whereas in the mated-fertile queen, the
grooves are completely filled with a waxy material, giving
the surface its matte appearance (Fig. 1;series2,AC).
When the wax was gently scrapped off, it uncovered the
grooves and rendered this portion of the cuticle shiny as in
virgin queens (Fig. 1;series2,BC).
Figure 2presents the chromatogram of shiny queen (a),
matte queen (b), and scraped wax from matte queens
23
4
567
8
9
10 11
12
13
14
15
17
16 18
19
20
21
22
23
24
25
26 27
12
4
67
8
10 11
17
18 20 22 23 24 27
12
14
15
12
4
67
8
10 11
17
18 20 22 23 24
12
14
18 20 22 24 26 28 30
Retention time (min.)
a Virgin female
b Mated female
c Scraped wax from
mated queen cuticle
Fig. 2 Chemical profiles of thoracic extracts of shiny and matte
Ectatomma tuberculatum queens (a,b) and extract of wax scrapped
off the thoracic cuticle of matte queens (c). Compounds names are
presented in Table 1
Naturwissenschaften (2008) 95:5560 57
cuticle (c). All extracts contained mostly hydrocarbons with
small amounts of oleic acid (not shown in the chromato-
grams), squalene, and cholesterol. There was a dramatic
increase in the total amount of extractable hydrocarbons
from shiny to matte queens (239± 62 and 5,709 ± 1,217 ng/
thorax [n=15; 22], respectively, unpaired ttest: t=3.65, p<
0.001). Although qualitatively, all extracts were similar, the
profile of shiny females was clearly distinguishable from
that of matte queens or the scraped wax. The latter two
showed high congruency. The major differences were in the
relative amounts of heptacosane and nonacosane. In shiny
queens, nonacosane was the major compounds (57.6 ±
13.6 ng/thorax), and the amounts of heptacosane were only
moderate (10.0±3.0 ng/thorax). In matte queens, in
contrast, although the amount of nonacosane increased to
1,922±526 ng/thorax, that of heptacosane increased even
more (2,583±518 μg/thorax), and it became the major
peak. Accordingly, the C
27
-to-C
29
ratio rose from 0.12±
0.05 to 1.55±0.08. These two compounds were also the
major compounds of the scraped wax.
We further made a peak-by-peak comparison between
mated females, virgin females with developed ovaries, and
virgin females with nondeveloped ovaries (Table 1). There
were no differences between virgin females that were field
collected or that emerged in the laboratory. All three groups
clearly differed from each other. Although the total amounts
of CHC in virgin females with developed ovaries was not
different from that of virgin females without developed
ovaries (109±38 [n= 5] and 298 ± 85 [n= 11], respectively;
unpaired ttest: t=1.45, p=0.1), several of the compounds
showed a shift (either decrease or increase in relative
intensity) that made them more similar to the mated queens.
Table 1 Chemical composition of CHC of queens Ectatomma tuberculatum, denoting the difference between queens; mated, virgin with
developed ovaries, and virgin with undeveloped ovaries
Relative abundance (mean±SE)
Peak number Compound Mated queens
(n=22)
Nonmated queens
ovaries developed
(n=5)
Nonmated queens ovaries
undeveloped (n=10)
1C
25
0.36± 0.03
a
0.95± 0.27
b
0.18± 0.04
c
2C
26
0.52± 0.03
a
0.75± 0.16
a
0.13± 0.03
b
3C
27:1
ND ND ND
4C
27
49.61± 1.29
a
12.83± 5.10
b
3.92± 2.20
c
5 11-+ 13-me C
27
0.01± 0.00
a
0.52± 0.16
b
0.67± 0.14
b
6 5-me C
27
0.38± 0.05
a
4.54± 2.31
b
0.75± 0.34
a
7 3-me C
27
0.26± 0.04
a
0.33± 0.09
a
0.18± 0.06
a
8C
28
5.84± 0.21
a
3.51± 0.70
b
1.32± 0.28
c
9 12-me C
28
0.02± 0.01
a
1.52± 0.61
b
1.33± 0.30
b
10 2-me C
28
0.30± 0.04
a
1.33± 0.37
b
0.66± 0.11
c
11 C
29:1
ND ND ND
12 C
29
33.51± 1.29
a
26.30± 3.34
a
16.92± 2.79
b
13 11-+ 13-me C
29
0.10± 0.02
a
10.87± 3.47
b
20.53± 3.72
b
14 7-me C
29
ND ND ND
15 5-me C
29
0.58± 0.06
a
0.39± 0.09
a,b
0.27± 0.20
b
16 11, 17-dme C
29
0.02± 0.00
a
0.97± 0.36
b
3.05± 0.63
c
17 3-me C
29
5.28± 0.46
a
4.75± 1.42
a
4.19± 0.39
a
18 C
30
0.34± 0.02
a
3.01± 1.11
b
1.03± 0.20
c
19 8-me C
30
0.13± 0.02
a
0.08± 0.02
a
0.62± 0.19
b
20 2-me C
30
ND ND ND
21 C
31
0.86± 0.10
a
4.91± 1.63
b
2.62± 0.54
c
22 11-+ 13-me C
31
0.07± 0.02
a
4.08± 1.06
b
10.86± 1.44
c
23 11,19-dme C
31
1.82± 0.26
a
18.36± 4.44
b
30.79± 3.25
c
24 3-me C
31
ND ND ND
25 11-+ 13-me C
33
ND ND ND
Peak numbers correspond to those in the chromatograms in Fig. 2. Peak-by-peak comparison of the three queen groups was done using the arcsin-
transformed percentages using a one-way ANOVA followed by a Tukey post-hoc test with αset at 0.05. For each compound, data followed by
different letters are significantly different. Compounds followed by ND were not quantified either because they were too small or not well
separated in the chromatograms, making their integration unreliable.
58 Naturwissenschaften (2008) 95:5560
Discussion
The composition analyses of CHC of virgin and mated
high-fertile queens of E. tuberculatum revealed that each
possesses a typical profile. The major difference is in the
relative proportions of two linear alkanes: Virgin queens are
typified by major amounts of nonacosane and minor
amounts of heptacosane, whereas this proportion is re-
versed in fertile queens. Moreover, mated queens have
greater amounts of CHC that cover the cuticular surface and
are responsible for the change in brightness. These
chemical changes may be related to ovarian development
because they started to occur already in virgin female that
had developed ovaries. However, as some of the virgin
queens were also the youngest, we cannot exclude age
effect on the chemistry (e.g., Cuvillier-Hot et al. 2001).
Furthermore, mated queens can be readily discerned by
their different phenotypic appearance. In the mated-fertile
queens, cuticle appearance turns from shiny to matte
because of the accumulation of waxy secretion on the
cuticular surface. These changes were not seen in the virgin
queens with developed ovaries, probably because the total
CHC amounts were still small. Changes in visual appear-
ance were also reported for the queenless ectatommine ant
Rhytidoponera sp. 12, where gamergates (mated-fertile
workers) differed from unmated workers by having a
reddish brown cuticle rather than the dark brown of
unmated workers (Tay and Crozier 2000). In the beetle
Cryptoglossa verrucosa, changes in cuticular lipids in
response to humidity resulted in color change from blue
to black (Hadley 1979).
The correlative nature of this study does not permit
unequivocal conclusions concerning the function of these
chemical and visual phenotype differences but raises
several hypotheses. An obvious hypothesis is that the
abundance of CHC gives extra protection to mated queens
against abiotic factors, e.g., temperature and soil particles,
which can raise water-loss rates (e.g., Gibbs 2002; Johnson
and Gibbs 2004). In the seed-harvester ant Pogonomyrmex
barbatus, for example, soil particles abrading the cuticle
during nest excavation can increase cuticular transpiration
in young queens (Johnson and Gibbs 2004). The semi-
claustral nest foundation in E. tuberculatum (Dejean and
Lachaud 1992) may have selected for more robust cuticular
surfaces of the queens to protect them during their
necessary foraging before the first workers emerge. Fur-
thermore, the occurrence of polydomy (a single colony
having multiple nests) and colony reproduction by budding
(departure of young queens and workers to found a new
colony near the mother colony (reviewed in Peeters and Ito
2001) were suggested to occur in Brazilian populations
(Hora et al. 2005; Zinck et al. 2007). Thus, queens may be
exposed more then usual to environmental stress, against
which the wax coat present in mated-fertile queens could
provide a protective barrier. However, the shift in the CHC
profiles of queens may favor an alternatively (but not
exclusive) hypothesis that the CHC may provide odor cues
to other nest members, workers and males, for discriminat-
ing between virgin and mated-fertile females through
physical contact (antennation, grooming, etc). Indeed,
workers interacted more frequently with fertile queens than
with virgin queens, and intranidal mating can take place both
in nature (Hora et al. 2005) and in artificial conditions
(Fénéron, personal communication). Such signals were
previously described, for example, in ponerine ants with or
without queens (e.g., Cuvillier-Hot et al. 2001;Heinzeetal.
2002; Liebig et al. 2000; Peeters et al. 1999). Finally, a study
has shown that in polygynous colonies, nestmate queens of
E. tuberculatum do not contest for dominance (Hora et al.
2005), which raises the possibility that these contest are
resolved through chemical cues (e.g., Moritz et al. 2000).
Notwithstanding, this is the first case to our knowledge
where external chemical changes are accompanied by
changes in visual appearance in ants.
Acknowledgements We are grateful to A. Viana, G. Costa, and J.
Santos for their assistance during the fieldwork and M. C. Malherbe
and C.-C. Lin for technical assistance. We also thank Naomi Paz for
editing the English and C. Alaux and referees for valuable comments
on the manuscript. R. R. Hora received a financial support from
CAPES, Brazil, Project CAPES/COFECUB no. 244/98-II, and J.
Delabie acknowledges his research grant from CNPq, Brazil. This
study was conducted under Brazil legal requirements.
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... Moreover, there was also a general increase in total CHC quantities after a queen mates [57]. Cuvillier-Hot and colleagues [54] attributed these changes to a hardening of the cuticle upon maturation, whereas Hora and colleagues [58] hypothesised that abundant CHCs provide mated queens with additional protection against abiotic factors that can increase rates of water loss, such as high temperatures or exposure to soil particles. Another non-exclusive explanation advanced by these authors is that these chemical changes provide odour cues to workers that allow them to discriminate between virgin (younger) and mated/fertile (older) queens [58]. ...
... Cuvillier-Hot and colleagues [54] attributed these changes to a hardening of the cuticle upon maturation, whereas Hora and colleagues [58] hypothesised that abundant CHCs provide mated queens with additional protection against abiotic factors that can increase rates of water loss, such as high temperatures or exposure to soil particles. Another non-exclusive explanation advanced by these authors is that these chemical changes provide odour cues to workers that allow them to discriminate between virgin (younger) and mated/fertile (older) queens [58]. Indeed, in the monogynous ant Aphaenogaster senilis, chemical differences between virgin and mated queens of the same age appear to be associated with physiological changes related to mating and egg laying; such differences could signal both caste and reproductive status [59]. ...
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In insect societies, chemical communication plays an important role in colony reproduction and individual social status. Many studies have indicated that cuticular hydrocarbons (CHCs) are the main chemical compounds encoding reproductive status. However, these studies have largely focused on queenless or monogynous species whose workers are capable of egg laying and have mainly explored the mechanisms underlying queen-worker or worker-worker reproductive conflicts. Less is known about what occurs in highly polygynous ant species with permanently sterile workers. Here, we used the Argentine ant as a model to examine the role of CHCs in communicating reproductive information in such insect societies. The Argentine ant is unicolonial, highly polygynous, and polydomous. We identified several CHCs whose presence and levels were correlated with queen age, reproductive status, and fertility. Our results also provide new insights into queen executions in the Argentine ant, a distinctive feature displayed by this species in its introduced range. Each spring, just before new sexuals appear, workers eliminate up to 90% of the mated queens in their colonies. We discovered that queens that survived execution had different CHC profiles from queens present before and during execution. More specifically, levels of some CHCs were higher in the survivors, suggesting that workers could eliminate queens based on their chemical profiles. In addition, queen CHC profiles differed based on season and species range (native vs. introduced). Overall, the results of this study provide new evidence that CHCs serve as queen signals and do more than just regulate worker reproduction.
... been identified, in Formica lugubris (Walter et al. 1993) and in Polyergus breviceps (Greenberg et al. 2007). The chemical bouquet produced by a queen changes once she is mated, as reflected in modifications of the relative abundances of cuticular hydrocarbons within hours or a few days from mating in several ant species (Hora et al. 2008;Monnin 2006;Oppelt and Heinze 2009) and in the honeybee (Babis et al. 2014). This is because mated queens never re-mate (Boomsma 2013) and hence need not attract males anymore and instead they need to advertise their fertility to colony members (Foitzik et al. 2011;Hannonen et al. 2002;Holman et al. 2010;Holman et al. 2013;Keller and Nonacs 1993;Le Conte and Hefetz 2008;Monnin 2006;Ruel et al. 2013;van Oystaeyen et al. 2014). ...
... Our results show that the complex chemical bouquet of C. cursor queens changes according to age, mating status and reproductive activity, as occurs in other species where mating triggers chemical switches (Babis et al. 2014;Hora et al. 2008;Oppelt and Heinze 2009). These changes are related to mate attraction and to queen signaling towards workers, and the identification of candidate chemicals is a first step towards identifying pheromones. ...
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Social insects are well known for their extremely rich chemical communication, yet their sex pheromones remain poorly studied. In the thermophilic and thelytokous ant, Cataglyphis cursor, we analyzed the cuticular hydrocarbon profiles and Dufour’s gland contents of queens of different age and reproductive status (sexually immature gynes, sexually mature gynes, mated and egg-laying queens) and of workers. Random forest classification analyses showed that the four groups of individuals were well separated for both chemical sources, except mature gynes that clustered with queens for cuticular hydrocarbons and with immature gynes for Dufour’s gland secretions. Analyses carried out with two groups of females only allowed identification of candidate chemicals for queen signal and for sexual attractant. In particular, gynes produced more undecane in the Dufour’s gland. This chemical is both the sex pheromone and the alarm pheromone of the ant Formica lugubris. It may therefore act as sex pheromone in C. cursor, and/or be involved in the restoration of monogyny that occurs rapidly following colony fission. Indeed, new colonies often start with several gynes and all but one are rapidly culled by workers, and this process likely involves chemical signals between gynes and workers. These findings open novel opportunities for experimental studies of inclusive mate choice and queen choice in C. cursor.
... Thus, males are under a strong competition to find a receptive partner within this short temporal window. Previous studies on bees as well as on other aculeate hymenopterans showed that changes in female attractiveness via CHC changes could be either due to an endogenous shift in their cuticular chemistry (Engels and Engels, 1988;Ayasse et al., 1999;Engels et al., 1997;Hora et al., 2008) or because of an anti-aphrodisiac being applied on the female by Fig. 2. Standardized differences of the% abundance of major peaks (> 1% in at least one group) between virgin and young mated females (A) and between young mated and old mated females (B) of S. continuus ((% in group 1 -% in group 2)/(% in group 1 + % in group 2)*100)). In A, positive bars indicate higher% in virgin females and negative bars indicate higher% in young mated females, while in B, positive bars indicate higher% in young mated females and negative bars indicate higher% in old mated females. ...
... Age-dependent changes in CHC profiles are not surprising per se since they normally occur due to physiological ageing processes (metabolism and gland development) and ovarian development (Jansen et al., 2015). For future studies, it would be interesting to examine if the CHC profile of S. continuus virgin females also shift with age independently of mating, as it was observed in few bees (Megachile rotundata Fabricius, Paulmier et al. (1999); Lasioglossum zephyrum (Smith), Barrows (1975); Apis mellifera L., Babis et al. (2014)) and few ants (Linepithema humile Mayr, de Biseau et al. (2004); Ectatomma tuberculatum (Olivier), Hora et al. (2008)). ...
Article
Females of most aculeate Hymenoptera mate only once and males are therefore under a strong competitive pressure which is expected to favour the evolution of rapid detection of virgin females. In several bee species, the cuticular hydrocarbon (CHC) profile exhibited by virgin females elicits male copulation attempts. However, it is still unknown how widespread this type of sexual communication is within Aculeata. Here, we investigated the use of CHCs as mating cues in the digger wasp Stizus continuus, which belongs to the family (Crabronidae) from within bees arose. In field experiments, unmanipulated, recently emerged virgin female dummies promptly elicit male copulation attempts, whereas 1-4 days old mated females dummies were still attractive but to a much lesser extent. In contrast, old (10-15 days) mated female dummies did not attract males at all. After hexane-washing, attractiveness almost disappeared but could be achieved by adding CHC extracts from virgin females even on hexane-washed old mated females. Thus, the chemical base of recognition of females as appropriate mating partner by males is coded in their CHC profile. Accordingly, differences in CHC profiles can be detected between sexes, with males having larger amounts of alkenes and exclusive long-chain alkanes, and within females specially according to their mating status. Shortly after mating, almost all of the major hydrocarbons found on the cuticle of females undergo significant changes in their abundance, with a clear shift from short-chain to long-chain linear and methyl-branched alkanes. The timely detection of virgin females by males in S. continuus could be advantageous within the narrow period of female emergence, when male-male competition is strongest.
... Greene & Gordon (2003) showed that in the desert ant Pogonomyrmex barbatus n-alkanes are used as a cue by the colony to modulate forager numbers. Hora et al. (2008) found that in the queens of the ant Ectatomma tuberculatum there was a 15-fold increase in the amount of n-alkanes on their cuticle after they were mated. This changed their physical appearance from shiny (virgin) to matte (mated) and the authors suggest that this could be used as a mating and fertility cue. ...
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Cuticular hydrocarbons are present on the surface of all insects and play an important role in the life of insects. Although primarily anti-desiccation agents, cuticular hydrocarbons are emerging as important chemicals in insect communication. Here we discuss the usefulness of hydrocarbons both as waterproofing and signalling compounds. The three major groups of hydrocarbons, i.e., n-alkanes, alkenes and methyl branched hydrocarbons, are discussed in detail. The biosynthesis of these cuticular hydrocarbons is briefly outlined as well as the role of cuticular hydrocarbons in taxonomy. In many nonhymenoptera insect studies, a simpler cuticular hydrocarbon profile has allowed researchers to identify the role of certain compounds, and the various functions of these are not spread evenly across the various groups of hydrocarbons. Due to the general complexity of many insect cuticular hydrocarbon profiles, which can contain upwards of 100 compounds, comparisons between groups are normally based on the entire profile using multi-variant statistical methods. Here, we highlight potential problems with the detection and analysis of cuticular hydrocarbons. By drawing information across a wide spectrum of studies it appears clear that the main role of the n-alkanes is to control transcuticular water movement while the unsaturated compounds and methyl-branched hydrocarbons are more likely to be involved in communication. If future studies can concentrate on determining initially which groups of cuticular hydrocarbons are of interest, it would help narrow down the search for the exact role of hydrocarbons in insect societies. This comprehensive introduction to cuticular hydrocarbons is aimed at the rapidly increasing number of scientists, especially biologists, who are studying the role of cuticular hydrocarbons in insect behaviour.
... In other species, CHC profiles correlate with mating status. In Ectatomma tuberculatum, queens exhibit a 250-fold increase in heptacosane quantity compared to gynes, which provokes a visible modification of the cuticle (Hora et al. 2008). Similarly, 30 min after mating, Leptothorax gredleri queens already show a significant increase in the proportion of linear alkanes and a decrease in dimethylalkanes (Oppelt and Heinze 2009). ...
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Ant queen pheromones (QPs) have long been known to affect colony functioning. In many species, QPs affect important reproductive functions such as diploid larvae sexualization and egg-laying by workers, unmated queens (gynes), or other queens. Until the 1990s, these effects were generally viewed to be the result of queen manipulation through the use of coercive or dishonest signals. However, in their seminal 1993 paper, Keller and Nonacs challenged this idea, suggesting that QPs had evolved as honest signals that informed workers and other colony members of the queen’s presence and reproductive state. This paper has greatly influenced the study of ant QPs and inspired numerous attempts to identify fertility-related compounds and test their physiological and behavioral effects. In the present article, we review the literature on ant QPs in various contexts and pay special attention to the role of cuticular hydrocarbons (CHCs). Although the controversy generated by Keller and Nonacs’ (Anim Behav 45:787–794, 1993) paper is currently less intensively debated, there is still no clear evidence which allows the rejection of the queen control hypothesis in favor of the queen signal hypothesis. We argue that important questions remain regarding the mode of action of QPs, and their targets which may help understanding their evolution.
... The compounds responsible for distinguishing queens and workers foram n-heptacosane (C 27 ) and n-nonacosane (C 29 ), which are more abundant in the cuticle of queens (Table 3). These compounds were also found by Hora et al. (2008) in the cuticle of Ectatomma tuberculatum (Olivier, 1792) and the authors suggested that the content of these compounds may signal the insemination of queens. In fact, Van Zweden et al. (2013) found the n-heptacosane compound in the highest concentration in the cuticle of the wasps of the Dolichovespula saxonic (Fabricius, 1793) wasp. ...
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An important attribute of the evolution and maintenance of sociality in insects is their ability to distinguish members of their own colonies by means of chemical signals during their interactions. From this type of signals, the cuticular hydrocarbons, is responsible for intraspecific recognition stand out, among other functions. Linear alkanes are indicated as the class of compounds that would be most involved in water retention in the body of insects, however, some studies have investigated their role as mediators of interactions. Thus it is possible that there is significant intraspecific variation of its composition, so the objective of this study was to test the hypothesis that linear alkanes vary significantly among populations, castes and sexes, as well as between newly emerged females of different ages of the Mischocyttarus consimilis Zikán 1949 wasp. The samples were analyzed by gas chromatography with flame ionization detector and gas chromatography coupled to mass spectrometry. The results show that there is a significant variation between the chemical cuticular profiles of samples from different populations, as well as between castes, sex and newly emergent workers of different ages. Therefore, it is possible to infer that this class of compounds may vary according to genetic differences between populations, but also by different environmental conditions. The differences between castes, sex and ages suggest that these compounds may also be involved in mediating interactions between nestmates.
... n-Heptacosane is found in the epi-cuticular wax layer of different insects and is the major male courtship pheromeone of Colias eurytheme (Sappington and Taylor, 1990). It has been reported that the cuticular hydrocarbons in social insects signal the reproductive status of an individual and n-heptacosane has been identified as the major hydrocarbon on the wax coat of the mated queen of the ants Ectatomma tuberculatum (Hora et al., 2008). ...
... PATO_0001373), refer to the reflectance quality of the cuticle. These relation phenotypes can only be observed under direct light (without light diffusers) and might correlate to the cuticular hydrocarbon profile (Hora et al. 2007(Hora et al. , 2010. ...
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Thesis
L'investissement des adultes pour augmenter la survie des jeunes est souvent optimisé par une communication émise par les jeunes et informant les parents de leur niveau de besoin. Nous avons exploré dans cette thèse si les comportements des larves de fourmi pouvaient être des quémandes alimentaires telles que définies par les modèles de communication honnête. En effet, les fourmis, eusociales, possèdent un système de relations sociales et de coopérations qui diffère du modèle parental classiquement décrit. Nous avons donc testé chez la fourmi Ectatomma tuberculatum si les comportements des larves pouvaient refléter leur niveau de besoin et si les ouvrières apportaient la nourriture en fonction du signal comme prédit par les modèles. Nous montrons dans cette thèse que les mouvements émis par les larves ainsi qu'un composé chimique volatil larvaire pourraient tous deux intervenir et influencer l'apport alimentaire par les ouvrières. Les mouvements larvaires augmentent avec le stade de développement des larves et le composé chimique augmenterait avec le niveau d'affamement des larves. Les ouvrières, nourrices et fourrageuses, pourraient donc optimiser la répartition des ressources alimentaires de la colonie grâce à ces signaux ou indices des larves. Cependant, nous montrons aussi que plusieurs autres facteurs proximaux interviennent. Les mouvements larvaires font suite à des contacts fortuits avec les ouvrières, et l'organisation spatiale des ouvrières et des larves influencent les mouvements larvaires et le nourrissage. Des hypothèses alternatives ou complémentaires à la communication sont donc proposées.
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Polygyny, the presence of several mated queens within the same colony, is widespread in insect societies. This phenomenon is commonly associated with ecological constraints such as limited nest sites. In habitats where solitary nest foundation is risky, monogynous colonies can reintegrate young daughter queens (secondary polygyny). We studied the reproductive structure (i.e. queen number) of the ectatommine ant Ectatomma tuberculatum from Bahia State, Brazil. This species was found to present facultative polygyny: out of a total of 130 colonies collected, 39.2% were monogynous, while 43.8% were polygynous. Polygynous colonies had significantly more workers than monogynous ones. Queen number in polygynous colonies ranged from 2 to 26, with an average of 4 4 queens per colony. All nestmate queens were egg-layers with no apparent dominance hierarchy or agonistic behavior. Non-nestmate queens were adopted by monogynous colonies suggesting that polygyny is secondary, originating through queen adoption. This species is characterized by an open recognition system, which probably allows a switch from monogynous to polygynous colonies. The behavioral acts of queens showed that resident queens remained frequently immobile on or near the brood, contrarily to alien or adopted queens and gynes. In addition, monogynous queens showed no behavioral or physiological (i.e. by ovarian status) differences in comparison with polygynous ones. Secondary or facultative polygyny, probably associated with queen adoption, may have been favored in particular environmental conditions. Indeed, by increasing colony productivity (i.e. number of workers) and territory size (by budding and polydomy), polygyny could uphold E. tuberculatum as a dominant species in the mosaic of arboreal ants in Neotropical habitats.
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We traced the development in the laboratory of 18 young colonies of the arboricolous ponerine antEctatomma tuberculatum. Colony foundation is of the partially-claustral type. During the early stages, when the colony is entirely dependent on the queen's behavior, the growth of the colony in terms of number of workers produced over time was relatively predictable. Afterwards, divergence in colony growth in function of the time increases as fast as the number of workers influences the efficiency of colony provisioning. Comparative analysis indicated clear changes in the predation behavior of foundresses and workers as colonies developed. For any stage of colony growth, all individuals provisioned the nest with dead prey or sugar-rich substances in the same way. However, prey hunting involves two different strategies. Foundresses and nanitic workers (originating from colonies with 9–15 workers) foraged actively, catching prey as the result of random encounters. Post-nanitic foragers (originating from colonies with 20–30 workers) and those from nature colonies developed an ambush strategy. Workers in these colonies gained experience at catching and handling prey during a period when they acted as nest guards, and so tended to be more efficient hunters than poorly experienced foundresses or nanitic foragers. The change in strategy was also positively correlated with an increase in the size of workers as the colony matured. A stable maximum in workers size is apparently reached only after the appearance of efficiently hunting foragers, presumably in numbers sufficient to provide adequate quantity and quality of larval food. Such a correlation between worker size and colony growth, assumed general for all ants, has not been demonstrated for Ponerinae before this work.
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Abstract. Queens and workers in social insect colonies can differ in reproductive goals such as colony-level sex allocation and production of males by workers. That the presence of queen(s) often seems to affect worker behaviour in situations of potential conflict has given rise to the idea of queen control over reproduction. In small colonies queen control is possible via direct aggression against workers, but in large colonies queens cannot be effectively aggressive towards all the workers. This, plus evidence that queen-produced chemicals affect worker behaviour, has led to the conclusion that physical intimidation has been replaced by pheromonal queen control, whereby queen(s) chemically manipulate workers into behaving in ways that increase the queen's fitness at the worker's expense. It is argued in this paper, however, that pheromonal queen control has never conclusively been demonstrated and is evolutionarily difficult to justify. Proposed examples of pheromonal control are more likely to be honest signals, with workers' responses increasing their own inclusive fitness. A series of experimental and field studies in which positive results would give prima facie evidence for pheromonal queen control is suggested. Finally, three terms are defined: (1) pheromonal queen control for workers or subordinate queens being chemically manipulated into acting against their own best interests; (2) pheromonal queen signal for situations where workers or subordinate queens react to queen pheromones in ways that increase their, and possibly the queens', inclusive fitness; and (3) pheromonal queen effect where changes in the workers' or subordinate queens' behaviour have an unknown consequence on their inclusive fitness.
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We investigated cuticular hydrocarbons and fatty acids of workers and queens from two ant species, Leptothorax acervorum and L. gredleri. Cuticular compounds were extracted from single ants by solvent extraction, solid sampling, and solid phase microextraction (SPME) with two different polydimethylsiloxane (PDMS) fibers and analyzed using GC and GC-MS. All three methods gave similar results, documenting that SPME can be applied to very small, live ants (body size appr. 3 mm). The hydrocarbon mixtures consisted mostly of branched and unbranched alkanes and alkenes within the range of C25 to C33. Dufour glands of both species contained a blend of hydrocarbons different from those found on the cuticle. In addition, terpenoids, especially tetramorenes were present in the Dufour gland contents. In a principal components analysis based on the relative proportions of cuticular compounds, most nestmate workers clustered in four groups corresponding to the original four investigated colonies. Queens and workers differed significantly in their chemical profiles, suggesting that the two castes bear specific labels.
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Eusocial insects display all of the following traits: cooperation among colony members in caring for the young; reproductive division of labour, with sterile individuals working on behalf of others engaged in reproduction; and overlap of at least 2 generations of life stages capable of contributing to colony labour. An evolutionary framework focuses attention on the social factors that regulate reproduction, though factors extrinstic to a colony are also examined. Major sections examine queen control (the influence a queen has on reproductive development in other individuals) and worker control, and factors leading to the regulation of queen number. -P.J.Jarvis
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The social biology of ants is interpreted from an adaptionist point of view, using the theory of natural section as a tool of explanation. Kin selection and the idea of the selfish gene underlie both cooperation and conflict within ant societies. Following an examination of the nature of kin selection, including issues relating to altruism, there follow chapters on levels-of-selection theory, gene selectionism and insect societies; kin selection, haplodiploidy and the evolution of eusociality in ants; and sex ratio theory (including appropriate tests). Subsequent chapters look at kin conflict over sex allocation and reproduction; the evolution and ecology of multiple-queen societies; life history theory and diversity in ants; mating biology; and the division of labour. -P.J.Jarvis
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Workers in de-queened colonies of the neotropical ant, Pachycondyla cf. inversa, form linear or near-linear dominance hierarchies by violent antennation and biting. In these rank orders, social status and ovarian activity are on average highly correlated. Whereas the presence of a fertile queen appears to be sufficient to prevent workers from laying eggs, fertile workers do not completely control reproduction by their nestmates, suggesting that workers are able to differentiate between an egg-laying queen and an egg-laying worker. Here we show that the composition of cuticular hydrocarbons of egg-laying workers is quantitatively and qualitatively different from that of non-laying workers and resembles the hydrocarbon blend of the queen but does not completely match it. Furthermore, using discriminant analysis, it was possible to distinguish workers with four different classes of ovarian development based only on their cuticular hydrocarbon profiles. Fertility-associated changes in cuticular hydrocarbons may play an important role in the behavioural regulation of reproduction in this ant.