Imagine you’re moving to a new house, and not only must you pack up all your belongings but also carry your children safely to the new home. Sounds stressful? For the Indian ant Diacamma indicum, this is pretty much their life story when they relocate their nest. A recent study in Myrmecological News shows that these ants tweak their behavioral strategies based on how many adults and young (also called brood) they need to move, maintaining efficient transport performance even as the load increases.

In ant societies, taking care of the brood–eggs, larvae, and pupae–is fundamental to colony survival. The brood not only represents the future workforce but is also essential for reproduction. Relocating the nest, a process often prompted by environmental disturbances such as flooding, becomes a high-stakes task when the brood must be moved safely along with the adults. Previous research has highlighted the importance of task specialization during relocation, but this study fills a critical gap by investigating how varying adult-to-brood ratios affect the overall relocation dynamics.

To explore relocation dynamics, researchers set up controlled laboratory experiments with Diacamma indicum [Figure 1] colonies. They manipulated brood levels to create three groups: colonies with natural brood levels (control, CT), brood-depleted colonies (with brood removed, B-), and brood-enhanced colonies (with additional brood added, B+). Then in an experimental relocation arena, they measured metrics such as relocation probability, the time taken to initiate relocation, overall relocation time, and the distribution of work among colony members.

The results were striking. Colonies with enhanced brood levels were significantly less likely to initiate relocation, with a notably higher latency before starting transport compared to control and brood-depleted colonies [Figure 2]. But here’s the twist—once the move began, the overall transport time and work distribution remained comparable across all groups. How’d they pull that off? The brood-enhanced colonies used a neat trick during the transport process by employing a coupled adult-brood strategy called tandem run with brood—where a single transport event moved both an adult and a brood item instead of just transporting either an adult or a brood item—allowing them to manage the increased load without extra time cost. Meanwhile, brood-depleted colonies behaved similarly to control colonies, suggesting that it is the presence of additional brood that sparks these smart behavioral adjustments.

All in all, the study shows the excellent adaptive strategy of these ants in response to changes in adult-to-brood ratios. This adaptive strategy ensures that, even under the stress of a heavy load, colonies can successfully move to a new nest without compromising efficiency. Returning to our human analogy, it’s like mastering a challenging move by fine-tuning your strategy when you suddenly find you have extra luggage—ensuring that everything, including your most valuable possessions, arrives safely at your new home.

Reference:

Ghosh, P., & Annagiri, S. (2023). Adult-brood ratio causes behavioural modifications to maintain transport performance during colony relocation in the ponerine ant Diacamma indicum (Hymenoptera: Formicidae). Myrmecological News, 33, 91–102. https://doi.org/10.25849/myrmecol.news_033:091

Purbayan Ghosh is a PhD student working under the lab of Professor Stephen Pratt at Arizona State University, USA. His research focuses on how behavior and physiology come together during nest site selection in the rock crevice nesting ant Temnothorax rugatulus. In general, he is interested in studying collective decision making in animal societies and the cognitive processes behind it. When not looking at ants, he enjoys traveling to new places, hiking, playing sports or hunting down the best food spots in the town.

[Edited by Isabelle McDonald and Nicole Rodrigues]