Author: Gosh, P. & Annagiri, S. Year: 2023 DOI: 10.25849/myrmecol.news_033:091 Title: Adult-brood ratio causes behavioural modifications to maintain transport performance during colony relocation in the ponerine ant Diacamma indicum (Hymenoptera: Formicidae) Journal: Myrmecological News Volume: 33 Pages: 91-102 URL: www.myrmecologicalnews.org Keywords: Social insect, non-trail-laying ants, tandem running, brood transport, work organization, behavioural flexibility. Abstract: Cooperative brood care is one of the most fundamental characteristics in the life history of eusocial insects. Still, while relocating to a new nest, bees and wasps abandon their offspring in the old nest, leading to a loss of colonies’ investments. Unlike other hymenopterans, ant colonies carry their brood with them while moving to a new nest. While brood transport enables colonies to retain their investment in the next generation, it makes the relocation process more complex in terms of time, effort, and organization. In the current study, we estimated the impact of brood transport on colony-level and individual-level organization during the goal-oriented task of relocation, using manipulative experiments. Using the eusocial ant Diacamma indicum Santschi, 1920 as the model system, we compared the relocation dynamics and work organization in brood-depleted (B-) colonies and brood-enhanced (B+) colonies with unmanipulated colonies. Upon performing 43 relocation experiments and examining 2516 unique transports, we found that B- colonies did not derive any significant advantage during transportation compared with brood intact control colonies. The sole reproductive female did not receive any special attention during the relocation in B- colonies. B+ colonies had a significantly lower probability of relocating despite having information about the location and quality of the new nest. However, B+ colonies that did relocate showed a significantly higher latency to start transportation; but having started, they performed relocation without any significant difference in time or work distribution. The colonies collectively adjusted their behaviour to accommodate and transport the additional brood in brood-enhanced colonies without spending extra time or doing more transports. We conclude that D. indicum ants have integrated brood transport with the relocation process in a seamless manner and can flexibly adjust their behaviour to transport their future reproductive and workforce with them when they occupy new nests without paying any additional cost. This is likely to give these superorganisms an advantage when they occupy new territories and enhance their survivability and reproduction. Publisher: The Austrian Society of Entomofaunistics ISSN: 1997-3500