Behavioural Mechanism of Relocation in an Indian Queenless Ant Diacamma indicum

Kaur, Rajbir (2014) Behavioural Mechanism of Relocation in an Indian Queenless Ant Diacamma indicum. PhD thesis, Indian Institute of Science Education and Research Kolkata.

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Abstract

Large number of individuals living together and showing cooperative brood care, reproductive division of labour and overlap of generations constitutes eusocial societies. Diacamma indicum is a primitively eusocial ant species from the subfamily Ponerinae and has been recorded in south-east Asia. Species lacks a morphologically distinct queen caste but a single mated individual, gamergate, takes up reproduction while all the others females in the colony serve as workers. Hardly any information is available regarding the species and this thesis represents the first focused study on D. indicum as the model system. Several factors cause animals to relocate their nests. Unlike, social bees or wasps which move only adult component of the colony, ants transport adults and brood to new nests whenever they relocate. While most ants use chemical trials to move to the new nest, D. indicum was seen employing a relatively primitive mode of transport, known as tandem running. It’s a stereotyped behaviour performed by a pair of ants known as tandem pair which includes tandem leader, an informed individual and a follower, the recruited member. As the follower keeps tapping her antennae onto the gaster of the tandem leader, throughout their journey, both tandem leader and follower remain physically informed about each other presence. Scouts explore their surroundings for potential new nests and upon encountering one they return to the old nest and invite their colony members one at a time to tandem run. The central purpose of this thesis was to understand the mechanism of relocation in D. indicum. The manner in which adults and brood are transported, the behaviour of tandem running and the characterization of tandem leaders were the main goals. A combination of experiments in the natural habitat of the ants and manipulative experiments in the lab allowed us to investigate these goals. Attention was paid to individual ants and their involvement in the relocation process was quantified and analyzed.

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