Reunification Without Information Transfer in Fragmented Diacamma indicum Ant Colonies

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ABSTRACT Nest relocation in social insects requires efficient communication among colony members. Ants such as Diacamma indicum perform nest relocation via tandem running where a tandem leader who is aware of the location of a potential new nest transports nestmates one at a time. During relocation, these ant colonies usually get fragmented into multiple temporary nests before reuniting at a single nest. Successful reunification would depend on tandem leaders obtaining information about multiple occupied sites, by following each other. These leader‐following‐leader (LFL) tandem runs allow leaders to compare multiple nests and potentially reunite at the best option. However, the importance of LFL in reunification has not been examined. To explore this, we used 39 D. indicum colonies that initially split into two target nests during relocation under one of the three experimental conditions: targeted LFL disruption, random tandem run disruption, and unmanipulated. We hypothesised that the absence of information transfer between leaders via LFL would impose a cost to colony reunification, as leaders would need to discover alternative sites through random search and thus take more time to relocate. We found that LFL disruption reduced the percentage of tandem leaders that switched to the final nest, indicating the importance of LFL in reunification. Nevertheless, reunification was not delayed. Instead, a higher percentage of leaders participated in reunification in the absence of LFL, indicating behavioural compensation when information is not exchanged among leaders. Further studies in more complex experimental setups closely mimicking the natural habitat are needed to fully understand LFL's contribution to maintaining colony cohesion and enhancing the efficiency of relocation.