scholarly journals Multi-functional roles of a soldier-specific volatile as a worker arrestant, primer pheromone and an antimicrobial agent in a termite

2017 ◽  
Vol 284 (1859) ◽  
pp. 20171134 ◽  
Author(s):  
Yuki Mitaka ◽  
Naoki Mori ◽  
Kenji Matsuura
Keyword(s):  
Communication Systems ◽  
Division Of Labour ◽  
Primer Pheromone ◽  
Evolutionary Mechanisms ◽  
Functional Roles ◽  
Eusocial Insects ◽  
Fungistatic Activity ◽  
Termite Soldier ◽  
Fungistatic Agent ◽  
Soldier Differentiation

Division of labour in eusocial insects is characterized by efficient communication systems based on pheromones. Among such insects, termites have evolved specialized sterile defenders, called soldiers. Because they are incapable of feeding themselves, it has been suggested that soldiers are sustained by workers and emit the pheromone arresting workers. However, such a soldier pheromone has not been identified in any termite species, and the details of the soldier–worker interaction remain to be explored. Here, we identified a soldier-specific volatile sesquiterpene as a worker arrestant, which also acts as a primer pheromone regulating soldier differentiation and fungistatic agent in a termite Reticulitermes speratus . Chemical analyses revealed that (−)- β -elemene is the major component of soldier extract, and its authentic standard exhibited arrestant activity to workers and inhibited the differentiation from workers to soldiers. This compound also showed fungistatic activity against entomopathogenic fungi. These suggest that (−)- β -elemene secreted by soldiers acts not only as a worker arrestant but also as one component of inhibitory primer pheromone and an anti-pathogenic agent. Our study provides novel evidence supporting the multi-functionality of termite soldier pheromone and provides new insights into the role of soldiers and the evolutionary mechanisms of pheromone compounds.

scholarly journals Polymorphism and division of labour in a socially complex ant: neuromodulation of aggression in the Australian weaver ant, Oecophylla smaragdina

2015 ◽  
Vol 282 (1811) ◽  
pp. 20150704 ◽  
Author(s):  
J. Frances Kamhi ◽  
Kelley Nunn ◽  
Simon K. A. Robson ◽  
James F. A. Traniello
Keyword(s):  
Social Systems ◽  
Division Of Labour ◽  
Oecophylla Smaragdina ◽  
Minor Worker ◽  
Task Specialization ◽  
Territorial Defence ◽  
Weaver Ant ◽  
Eusocial Insects ◽  
Worker Size ◽  
Pharmacological Manipulations

Complex social structure in eusocial insects can involve worker morphological and behavioural differentiation. Neuroanatomical variation may underscore worker division of labour, but the regulatory mechanisms of size-based task specialization in polymorphic species are unknown. The Australian weaver ant, Oecophylla smaragdina , exhibits worker polyphenism: larger major workers aggressively defend arboreal territories, whereas smaller minors nurse brood. Here, we demonstrate that octopamine (OA) modulates worker size-related aggression in O. smaragdina . We found that the brains of majors had significantly higher titres of OA than those of minors and that OA was positively and specifically correlated with the frequency of aggressive responses to non-nestmates, a key component of territorial defence. Pharmacological manipulations that effectively switched OA action in major and minor worker brains reversed levels of aggression characteristic of each worker size class. Results suggest that altering OA action is sufficient to produce differences in aggression characteristic of size-related social roles. Neuromodulators therefore may generate variation in responsiveness to task-related stimuli associated with worker size differentiation and collateral behavioural specializations, a significant component of division of labour in complex social systems.

scholarly journals Solitary bees reduce investment in communication compared with their social relatives

2017 ◽  
Vol 114 (25) ◽  
pp. 6569-6574 ◽  
Author(s):  
Bernadette Wittwer ◽  
Abraham Hefetz ◽  
Tovit Simon ◽  
Li E. K. Murphy ◽  
Mark A. Elgar ◽  
...  
Keyword(s):  
Social Behavior ◽  
Communication Systems ◽  
Group Membership ◽  
Group Living ◽  
Signal Perception ◽  
Eusocial Insects ◽  
Social Species ◽  
Solitary Living ◽  
Social Animals ◽  
Signal Production

Social animals must communicate to define group membership and coordinate social organization. For social insects, communication is predominantly mediated through chemical signals, and as social complexity increases, so does the requirement for a greater diversity of signals. This relationship is particularly true for advanced eusocial insects, including ants, bees, and wasps, whose chemical communication systems have been well-characterized. However, we know surprisingly little about how these communication systems evolve during the transition between solitary and group living. Here, we demonstrate that the sensory systems associated with signal perception are evolutionarily labile. In particular, we show that differences in signal production and perception are tightly associated with changes in social behavior in halictid bees. Our results suggest that social species require a greater investment in communication than their solitary counterparts and that species that have reverted from eusociality to solitary living have repeatedly reduced investment in these potentially costly sensory perception systems.

scholarly journals Dopamine regulates termite soldier differentiation through trophallactic behaviours

2016 ◽  
Vol 3 (2) ◽  
pp. 150574 ◽  
Author(s):  
Hajime Yaguchi ◽  
Takaya Inoue ◽  
Ken Sasaki ◽  
Kiyoto Maekawa
Keyword(s):  
Social Insects ◽  
Caste Differentiation ◽  
Multiple Roles ◽  
Intrinsic Factors ◽  
Termite Soldier ◽  
Species Specific ◽  
Incipient Colony ◽  
Soldier Differentiation ◽  
Gene Expression Levels

Caste polyphenism in social insects is regulated by social interactions among colony members. Trophallaxis is one of the most frequently observed interactions, but no studies have been conducted identifying the intrinsic factors involved in this behaviour and caste differentiation. Dopamine (DA) has multiple roles in the modulation of behaviours and physiology, and it produces species-specific behaviours in animals. Here, to verify the role of DA in termite soldier differentiation, we focused on the first soldier in an incipient colony of Zootermopsis nevadensis , which always differentiates from the oldest 3rd instar (No. 1 larva) via a presoldier. First, brain DA levels of the No. 1 larva at day 3 after its appearance were significantly higher than day 0. Second, DA synthesis gene expression levels were extraordinarily high in the No. 1 larva at day 0–1 after appearance. Finally, injection of a DA receptor antagonist into the No. 1 larva resulted in the inhibition of presoldier differentiation. Behavioural observations of the antagonist or control-injected larvae suggested that brain DA and signalling activity regulate the frequencies of trophallaxis from reproductives and presoldier differentiation. Because trophallaxis is a social behaviour frequently observed in natural conditions, the role of DA should be investigated in other social insects with frequent trophallactic and allogrooming behaviour.

scholarly journals The effect of age on non-reproductive division of labour in the tropical primitively eusocial wasp, Ropalidia cyathiformis

2020 ◽  
Vol 64 (4-5-6) ◽  
pp. 267-273
Author(s):  
Sruthi Unnikrishnan ◽  
Raghavendra Gadagkar
Keyword(s):  
Division Of Labour ◽  
Age Polyethism ◽  
Relative Age ◽  
Eusocial Insects ◽  
Primitively Eusocial Wasp ◽  
Eusocial Wasp ◽  
Reproductive Division Of Labour ◽  
Absolute Age ◽  
Reproductive Division ◽  
Primitively Eusocial

Division of labour among workers (non-reproductive division of labour), a characteristic feature of eusocial insects enables the efficient functioning of their colonies. In many advanced insect societies division of labour is based on age (age polyethism). Primitively eusocial insects however are believed to have a weak age polyethism. Here we investigated the role of age in non-reproductive division of labour in the tropical primitively eusocial wasp, Ropalidia cyathiformis and compared it with that in Ropalidia marginata, a congeneric species that exhibits relatively strong age polyethism. Age had a significant effect on the first performance of the four tasks studied; tasks were initiated in the sequence feed larva, build, bring food and bring building material. We measured task performance as the absolute frequency of tasks performed (FTP) and the probability of performing a task relative to other tasks (PTP) and age as absolute age in days since eclosion as well as relative age compared to nestmates. FTP varied significantly with both absolute and relative age, although absolute age explained more variance. PTP varied significantly with absolute age but not always with relative age. This is contrary to R. marginata, where more variation is explained by relative age than by absolute age. There was no trade-off between intranidal and extranidal tasks in R. cyathiformis unlike in R. marginata where the frequency of intranidal tasks decreased and that of extranidal tasks increased with age. We conclude that age polyethism is weak and less flexible in R. cyathiformis compared to that in R. marginata.

Naked mole-rats (Heterocephalus glaber) do not specialise on cooperative tasks

2021 ◽  
Author(s):  
Susanne Siegmann ◽  
Romana Feitsch ◽  
Daniel W Hart ◽  
Nigel C Bennett ◽  
Dustin J Penn ◽  
...  
Keyword(s):  
Body Mass ◽  
Division Of Labour ◽  
Behavioural Plasticity ◽  
Specific Work ◽  
Heterocephalus Glaber ◽  
Eusocial Insects ◽  
Cooperative Tasks ◽  
Trade Offs ◽  
Mole Rat ◽  
Work Tasks

It has been proposed that naked mole-rat (Heterocephalus glaber) societies resemble those of eusocial insects by showing a division of labour among non-breeding individuals. Earlier studies suggested that non-breeders belong to distinct castes that specialise permanently or temporarily on specific cooperative tasks. In contrast, recent research on naked mole-rats has shown that behavioural phenotypes are continuously distributed across non-breeders and that mole-rats exhibit considerable behavioural plasticity suggesting that individuals may not specialise permanently on work tasks. However, it is currently unclear whether individuals specialise temporarily and whether there is a sex bias in cooperative behaviour among non-breeders. Here we show that non-breeding individuals vary in overall cooperative investment, but do not specialise on specific work tasks. Within individuals, investment into specific cooperative tasks such as nest building, food carrying and burrowing are positively correlated, and there is no evidence that individuals show trade-offs between these cooperative behaviours. Non-breeding males and females do not differ in their investment in cooperative behaviours and show broadly similar age and body mass related differences in cooperative behaviours. Our results suggest that non-breeding naked mole-rats vary in their overall contribution to cooperative behaviours and that some of this variation may be explained by differences in age and body mass. Our data provide no evidence for temporary specialisation, as found among some eusocial insects, and suggests that the behavioural organisation of naked mole-rats resembles that of other cooperatively breeding vertebrates more than that of eusocial insect species.

Layer-specific differences of gene expression in extraocular muscles identified by laser-capture microscopy

2004 ◽  
Vol 20 (1) ◽  
pp. 55-65 ◽  
Author(s):  
Murat T. Budak ◽  
Sasha Bogdanovich ◽  
Martin H. J. Wiesen ◽  
Olga Lozynska ◽  
Tejvir S. Khurana ◽  
...  
Keyword(s):  
Metabolic Pathways ◽  
Extraocular Muscles ◽  
Molecular Evidence ◽  
Structural Elements ◽  
Evolutionary Mechanisms ◽  
Functional Roles ◽  
Laser Capture Microscopy ◽  
Vascular Elements ◽  
Genes Encoding ◽  
Laser Capture

In mammals, separate muscles are typically specialized as a whole to provide distinct functional roles leading to well-recognized adaptations. This is exemplified in the lower limb by the slow, fatigue-resistant soleus, which provides a postural role vs. the fast, fatiguable tibialis anterior (TA), which provides rapid movements. A unique characteristic of extraocular muscles (EOMs) is their compartmentalization into two distinct layers, the orbital layer (OL) and global layer (GL), presumably to subserve diverse functions within the same muscle. However, molecular evidence of this diversity has been limited. We used laser-capture microscopy coupled with microarray-based expression profiling to identify molecular differences between the OL and GL of rat EOMs. We found that 210 genes were differentially regulated between these layers at a twofold expression cutoff. Differences in genes related to metabolic pathways and related to structural elements of muscle and nerve formed the largest functional clusters. Layer-specific differential expression was validated at both mRNA and protein level for MYH3, MYH6, and ACTN3. The expected layer-specific differences among genes encoding vascular elements were not evident by profiling; morphometric analysis demonstrated that the differences exist, but at a magnitude below the cutoff level established by our statistical methods. Comparison of these results with previous results comparing whole EOMs and TA suggest evolutionary mechanisms may play a role in achieving functional distinctions between OL and GL.

Carriers and cutters: size-dependent caste polyethism in the tropical fire ant (Solenopsis geminata)

2019 ◽  
Vol 110 (3) ◽  
pp. 388-396
Author(s):  
Ming-Chung Chiu ◽  
Wen-Jer Wu ◽  
Li-Chuan Lai
Keyword(s):  
Gaussian Mixture ◽  
Division Of Labour ◽  
Fire Ant ◽  
Life History Trait ◽  
Head Width ◽  
Large Prey ◽  
Task Partitioning ◽  
Solenopsis Geminata ◽  
Eusocial Insects ◽  
Large Worker

AbstractBody size is an important life-history trait in eusocial insects which plays a key role in colony fitness. The division of labour, represented by caste polyethism, correlates with divergent morphological traits. Size polymorphism has been noted in the tropical fire ant, Solenopsis geminata; however, little is known regarding the differences in the size distributions of workers performing foraging tasks. In the present study, task partitioning was observed in the foraging activities of S. geminata. Two subgroups among foraging workers of S. geminata were discovered using the Gaussian mixture model: a large worker group (head width ≥ 0.924 mm) and a small worker group (head width < 0.924 mm). The foraging worker population comprised two distinct groups – 25.64% were large workers and 74.36% were small workers. Larger workers delivered heavier seeds faster than smaller workers, but this difference became less apparent when lighter seeds were being carried. When large prey such as crickets was encountered during foraging, S. geminata partitioned their tasks into cutting and transportation. The large workers were observed to cut cricket prey into fragments with their longer mandibles, and the small workers then transported these fragments back to the nest. These results present evidence of task partitioning among tropical fire ants, with different tasks being performed by ants of different castes.

Ergonomic skew and reproductive queuing based on social and seasonal variation in foraging activity of eastern carpenter bees (Xylocopa virginica)

2015 ◽  
Vol 93 (8) ◽  
pp. 615-625 ◽  
Author(s):  
M.H. Richards ◽  
C. Course
Keyword(s):  
Division Of Labour ◽  
Foraging Activity ◽  
Dominance Hierarchies ◽  
Carpenter Bee ◽  
Eusocial Insects ◽  
Carpenter Bees ◽  
Behavioural Interactions ◽  
Reproductive Division Of Labour ◽  
Xylocopa Virginica ◽  
Reproductive Division

Reproductive division of labour in social carpenter bees differs from that in classically eusocial insects because reproductive output and ergonomic inputs are positively correlated—dominant females monopolize both foraging and reproduction. We quantified ergonomic skew in the facultatively social bee Xylocopa virginica (L., 1771) (eastern carpenter bee) based on detailed observations of foraging activity by individually marked females in 2009. Unusually for a univoltine bee, this species exhibits a spring foraging phase during which females feed pollen to other adults, probably as part of behavioural interactions to establish dominance hierarchies. During brood-provisioning, foraging in social nests was dominated by one female at a time, with replacement by a succession of foragers as dominants disappeared and were succeeded by a subordinate. The principal foragers (individuals that did the largest share of foraging in each colony) did 85%–100% of all pollen trips, so contributions to pollen-provisioning by female nest mates were highly uneven. Individual foraging rate was unaffected by group size and total colony foraging effort was a function of the number of foragers per group. Transient females that moved to new nests were as successful in achieving dominant forager status as females resident in their natal nests. This evidence indicates that colony social organisation is based on reproductive queues, whereby the first-ranked bee is the dominant forager and subordinates queue for opportunities to replace her.

scholarly journals Asymmetry, division of labour and the evolution of ageing in multicellular organisms

2021 ◽  
Vol 376 (1823) ◽  
pp. 20190729 ◽  
Author(s):  
Ido Pen ◽  
Thomas Flatt
Keyword(s):  
Evolutionary Biology ◽  
Germ Line ◽  
Division Of Labour ◽  
Cellular Damage ◽  
Theme Issue ◽  
Basic Principles ◽  
Unequal Distribution ◽  
Eusocial Insects ◽  
Unicellular Organisms ◽  
Multicellular Organisms

Between the 1930s and 1960s, evolutionary geneticists worked out the basic principles of why organisms age. Despite much progress in the evolutionary biology of ageing since that time, however, many puzzles remain. The perhaps most fundamental of these is the question of which organisms should exhibit senescence and which should not (or which should age rapidly and which should not). The evolutionary origin of ageing from a non-senescent state has been conceptually framed, for example, in terms of the separation between germ-line and soma, the distinction between parents and their offspring, and—in unicellular organisms—the unequal distribution of cellular damage at cell division. These ideas seem to be closely related to the concept of ‘division of labour' between reproduction and somatic maintenance. Here, we review these concepts and develop a toy model to explore the importance of such asymmetries for the evolution of senescence. We apply our model to the simplest case of a multicellular system: an organism consisting of two totipotent cells. Notably, we find that in organisms which reproduce symmetrically and partition damage equally, senescence is still able to evolve, contrary to previous claims. Our results might have some bearing on understanding the origin of the germ-line–soma separation and the evolution of senescence in multicellular organisms and in colonial species consisting of multiple types of individuals, such as, for example, eusocial insects with their different castes.This article is part of the theme issue ‘Ageing and sociality: why, when and how does sociality change ageing patterns?'

scholarly journals A lipocalin protein, Neural Lazarillo, is key to social interactions that promote termite soldier differentiation

2018 ◽  
Vol 285 (1883) ◽  
pp. 20180707 ◽  
Author(s):  
Hajime Yaguchi ◽  
Shuji Shigenobu ◽  
Yoshinobu Hayashi ◽  
Satoshi Miyazaki ◽  
Kouhei Toga ◽  
...  
Keyword(s):  
Social Communication ◽  
Social Evolution ◽  
Differentially Expressed Gene ◽  
Social Signals ◽  
Crucial Component ◽  
Insect Societies ◽  
Termite Soldier ◽  
Molecular Phylogenetic ◽  
Incipient Colony ◽  
Soldier Differentiation

Social communication among castes is a crucial component of insect societies. However, the genes involved in soldier determination through the regulation of inter-individual interactions are largely unknown. In an incipient colony of the damp-wood termite Zootermopsis nevadensis , the first larva to develop into a third instar always differentiates into a soldier via frequent trophallactic feeding from the reproductives. Here, by performing RNA-seq analysis of third instar larvae, a homologue of Neural Lazarillo (named ZnNLaz1 ) was found to be the most differentially expressed gene in these soldier-destined larvae, compared with worker-destined larvae. This gene encodes a lipocalin protein related to the transport of small hydrophobic molecules. RNAi-induced knockdown of ZnNLaz1 significantly inhibited trophallactic interactions with the queen and decreased the soldier differentiation rates. This protein is localized in the gut, particularly in the internal wall, of soldier-destined larvae, suggesting that it is involved in the integration of social signals from the queen through frequent trophallactic behaviours. Based on molecular phylogenetic analysis, we suggest that a novel function of termite NLaz1 has contributed to social evolution from the cockroach ancestors of termites. These results indicated that a high larval NLaz1 expression is crucial for soldier determination through social communication in termites.

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