Social isolation regulates task dependent interspecific aggression in the ant, Formica japonica
-
1
Hokkaido University, Research Institute for Electronic Science, Japan
Aggressive behavior is elicited in most of all animals for conflict not only among intraspecific animals but also among interspecific animals. Insects provide us great model system for investigation of the neuronal mechanisms underlying initiation of aggressive behavior. Insects show offensive and defensive aggressive behaviors as well as in vertebrates. In ants, offensive and defensive aggressions towards hetero-colonial intraspecific animals have been well studied. However, the neuronal mechanisms underlying the initiation of aggressive behavior are still lacking. Here, we focus on interspecific aggressive behavior and examine the role in aggressive behavior of brain biogenic amines in the ants, Formica japonica. This ant is one of the most common species in Japan. The colonies of this species are largely polygynous and contain thousands of workers and brood. F. japonica is a polyphagous and the foragers sometime hunt other small insects and take them into the nest as foods.
The worker ants in a colony have different tasks, for example, nursing, nest maintenance, guard and foraging. In this study, predatory aggression towards a cricket as a prey was examined in the nest-builder, forager and guard. Behavior experiments demonstrate that interspecific aggressiveness was significantly higher in foragers and guards than nest-builders. Foragers and guards show predatory aggressive behavior towards crickets. They threated and attacked crickets. Usually they bite and captured crickets. However, nest-builders showed escape behavior without threating crickets.
Interestingly, the interspecific aggressiveness was maintained by intraspecific interactions. In order to investigate effects of social interaction on workers’ aggressiveness, each worker was kept isolated socially. Social isolation for 6 hr decreased aggressiveness in foragers and guard, but increased in nest-builders. Foragers and guards that were kept socially isolated for 6 hr showed threat behavior but did not attack crickets. On the other hand, nest builders that were kept isolated for 6 hr showed threat behavior. Then, in order to investigate neuronal mechanisms underlying initiation of predatory aggressive behavior, the contents of brain biogenic amines in workers was examined using high-performance liquid chromatography (HPLC) with electrochemical detection (ECD). Octopamine (OA) level in the brain was significantly higher in foragers and in guards than in nest builders. Social isolation decreased brain OA level of foragers and guards but increased in the brain of nest-builders. Pharmacological experiments were then performed to examine if OA increases aggressiveness of the workers. Oral application of OA antagonist epinastine decreases aggressiveness of foragers. In contrast, oral application of OA increased aggressiveness of socially isolated foragers. These experiments strongly suggested that OA in the brain regulates task-dependent aggressive motivation in the ants.
Acknowledgements
This research was partly supported by grants-in-aid for Scientific Research (KAKENHI) from the MEXT, Scientific Research on Priority Areas (Area No. 454) to H. Aonuma (No. 17075001) and from the JSPS to H. Aonuma (No. 23300113).
Keywords:
aggressive behavior,
biogenic amine,
Brain,
Octopamine,
social insect,
Social Isolation
Conference:
Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012.
Presentation Type:
Poster Presentation (see alternatives below as well)
Topic:
Social Behavior
Citation:
Aonuma
H
(2012). Social isolation regulates task dependent interspecific aggression in the ant, Formica japonica.
Conference Abstract:
Tenth International Congress of Neuroethology.
doi: 10.3389/conf.fnbeh.2012.27.00180
Copyright:
The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers.
They are made available through the Frontiers publishing platform as a service to conference organizers and presenters.
The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated.
Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed.
For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.
Received:
28 Apr 2012;
Published Online:
07 Jul 2012.
*
Correspondence:
Dr. Hitoshi Aonuma, Hokkaido University, Research Institute for Electronic Science, Sapporo, Hokkaido, 060-0812, Japan, aon@sapphire.kobe-u.ac.jp