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 Caste-specific phenotypic plasticity of Asian weaver ants: Revealing the allometric and non-allometric component of female caste system of Oecophylla smaragdina (Hymenoptera: Formicidae) by using geometric morphometrics

Sociobiology ◽  
2021 ◽  
Vol 68 (2) ◽  
pp. 5941
Author(s):  
K. V. Mahima ◽  
P. P. Anand ◽  
S. Seena ◽  
K. Shameema ◽  
E. M. Manogem ◽  
...  
Keyword(s):  
Morphological Characteristics ◽  
Morphological Characters ◽  
Caste Differentiation ◽  
Caste System ◽  
Oecophylla Smaragdina ◽  
Minor Worker ◽  
Geometric Morphometric ◽  
Eusocial Insects ◽  
Traditional Taxonomy ◽  
Worker Caste

In eusocial insects, particularly in ants, caste differentiation is extremely complicated when we rely on traditional taxonomy. In most species, the worker caste does not display any distinct morphological characters neither the caste’s central division according to their morphological size variations. We used a landmark-based geometric morphometric approach to quantify the morphological characteristics of female caste systems (queen, major and minor worker ant) of Oecophylla smaragdina. Our findings suggested that each caste has its unique shape and size. Especially in the worker caste, apart from the size variations, we can use the shape as a prominent tool for distinguishing between them. The O. smaragdina exhibits a triphasic allometry pattern. Studying the allometry and non-allometry components of each caste system revealed a highly complex size and shape relationship in the female caste systems. From the allometric and non-allometric analysis, we concluded that the major worker ants showed a closer relationship with the queen than the minor worker ant. This outcome demonstrated that Asian weaver ant exhibits complex shape variations related to size and is correlated to their functional modular characters. This research sheds new light on caste systems’ taxonomic uncertainties for eusocial hymenopteran groups, especially ants.

scholarly journals Oecophyllibacter saccharovorans gen. nov. sp. nov., a bacterial symbiont of the weaver ant Oecophylla smaragdina

2020 ◽  
Vol 58 (12) ◽  
pp. 988-997
Author(s):  
Kah-Ooi Chua ◽  
Wah-Seng See-Too ◽  
Jia-Yi Tan ◽  
Sze-Looi Song ◽  
Hoi-Sen Yong ◽  
...  
Keyword(s):  
Bacterial Symbiont ◽  
Oecophylla Smaragdina ◽  
Weaver Ant

scholarly journals Despotic aggression in pre-moulting painted buntings

2020 ◽  
Vol 7 (2) ◽  
pp. 191510
Author(s):  
Vanya G. Rohwer ◽  
Sievert Rohwer ◽  
John C. Wingfield
Keyword(s):  
Breeding Season ◽  
Social Systems ◽  
Passerine Bird ◽  
Adult Males ◽  
Territorial Defence ◽  
Painted Bunting ◽  
High Aggression ◽  
Limited Food ◽  
Ideal Despotic ◽  
Territorial Systems

Aggression in territorial social systems is easy to interpret because the benefits of territorial defence mostly accrue to the territorial holder. However, in non-territorial systems, high aggression seems puzzling and raises intriguing evolutionary questions. We describe extreme rates of despotism between age classes in a passerine bird, the painted bunting ( Passerina ciris ), during the pre-moulting period. Aggressive encounters were not associated with aggressors gaining immediate access to resources. Instead, conspecifics, and even other species, were pursued as though being harassed; this aggression generated an ideal despotic habitat distribution such that densities of adult males were higher in high-quality sites. Aggression was not a by-product of elevated testosterone carried over from the breeding season but, rather, appeared associated with dehydroepiandrosterone, a hormone that changes rates of aggression in non-breeding birds without generating the detrimental effects of high testosterone titres that control aggression in the breeding season. This extraordinary pre-moult aggression seems puzzling because individual buntings do not hold defined territories during their moult. We speculate that this high aggression evolved as a means of regulating the number of conspecifics that moulted in what were historically small habitat patches with limited food for supporting the extremely rapid moults of painted buntings.

scholarly journals Body Size Differences between Foraging and Intranidal Workers of the Monomorphic Ant Lasius niger

Insects ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 433
Author(s):  
Mateusz Okrutniak ◽  
Bartosz Rom ◽  
Filip Turza ◽  
Irena M. Grześ
Keyword(s):  
Body Size ◽  
Field Experiment ◽  
Important Determinant ◽  
Size Variation ◽  
Division Of Labour ◽  
The Body ◽  
Food Type ◽  
Lasius Niger ◽  
Worker Size ◽  
Body Sizes

The association between the division of labour and worker body size of ants is typical for species that maintain physical castes. Some studies showed that this phenomenon can be also observed in the absence of distinct morphological subcastes among workers. However, the general and consistent patterns in the size-based division of labour in monomorphic ants are largely unidentified. In this study, we performed a field experiment to investigate the link between worker body size and the division of labour of the ant Lasius niger (Linnaeus, 1758), which displays limited worker size variation. We demonstrated that the body size of workers exploring tuna baits is slightly but significantly smaller than the size of workers located in the upper parts of the nest. Comparing the present results with existing studies, large workers do not seem to be dedicated to work outside the nest. We suggest that monomorphic workers of certain body sizes are flexible in the choice of task they perform, and food type may be the important determinant of this choice.

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