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

Kamhi, J. Frances, Nunn, Kelley, Robson, Simon K.A., and Traniello, James F.A. (2015) Polymorphism and division of labour in a socially complex ant: neuromodulation of aggression in the Australian weaver ant, Oecophylla smaragdina. Proceedings of the Royal Society of London Series B, Biological Sciences, 282 (1811). pp. 1-9.

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Abstract

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.

Item ID: 41614
Item Type: Article (Refereed Research - C1)
Keywords: neuromodulation, octopamine, territorial aggression, polymorphism, division of labour
ISSN: 1471-2954
Funders: National Science Foundation (NSF), USA, Australian Research Council (ARC), ARC Discovery Grant 1093553
Projects and Grants: NSF EAPSI 20150704, NSF grant IOB-0725013, NSF grant IOS-1354291
Research Data: http://dx.doi.org/10.5061/dryad.36s2m
Date Deposited: 08 Dec 2015 14:05
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060201 Behavioural Ecology @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 100%
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