Bipartite network analysis of task-ant associations reveals task groups and absence of colonial diurnal activity

Division of labour is the key factor leading to higher-order systems such as cooperative animal groups. How division of labour is achieved without a central control is one of the most fascinating questions in behavioural ecology and complex systems science. Social insects are one of the best examples of complex self-organised systems through local interactions. However, it is difficult to comprehensively understand division of labour due to the chronological and individual variation in behaviours, and the differences between social environments. Thus, it is imperative to quantify individual behaviours and integrate them into colony levels. Here, we demonstrate that network analyses on individual-behaviour relationships can be valid for characterising the task allocation patterns. We recorded the behaviours of all individuals with verified age in colonies of monomorphic ant and analysed the individual-behaviour relationship at individual, sub-network, and network-levels. We detected the “task groups” including subsets of individuals and behaviour, and the patterns of task groups were consistent throughout the day. We also found a relationship between the age and the characteristics of individuals within the network. These findings suggest that bipartite network analyses can untangle the complex task allocation patterns and provide novel insights into understanding how division of labour is achieved.