Halder, E. | bioRxiv Science

bioRxiv2023

Marching with ants to a new nest

In this review, we journey with Diacamma indicum a Ponerine ant over the last decade as they relocate to new nests and discover the challenges they face along the way and how they solve them. Colony relocation is a goal oriented dynamic task that involves all the colony members and impacts the colonies fitness. After explaining how I initiated this journey, we examine colony composition of this species by analysing data from 1200 colonies collected over the last 13 years. On average colonies are constituted with 89.35 adult females, 0.29 males and 56.6 brood items of different development stages and these were significantly impacted by seasonality with Pre monsoon having the highest numbers. After explaining how colonies are collected and maintained in the lab, we explore the architectural components of the subterrain nests built by this species in the natural habitat. Colonies live in relatively simple single chambered nest that does not change significantly across seasons and consists of an entrance tunnel and a secondary runoff tunnel. All members of the colony are recruited to the new nest through tandem running and this species shows the highest documented tandem running speeds at 4.35 body lengths per second and a path efficiency of 83.95% with only 2.4% of tandem runs being unsuccessful in the natural habitat. Even in lab conditions, when colonies are given defined paths of different lengths, colonies showed significant preference to travel through short paths, highlighting their ability to optimizes their path even in the absence of chemical trails. A combination of experiments in the natural habitat and controlled experiments in the lab which are anchored in the umwelt of the organism has enabled us to understand how D. indicum functions and reveals the selection forces that are operating on the organization and performances of relocation. Our journey has brought to light several answers but has opened several more avenues for exploration branching out in different directions. With time and dedicated minds, we hope to continue on this route to marvel at the achievements of these superorganisms.

ecology↗

bioRxiv2023

Intraspecific competition for a nest and its implication for the fitness of relocating ant colonies

Competitive interaction is important in structuring species composition of a habitat. Several studies have been conducted on intraspecific competition but little is known in the context of the goal-oriented task of colony relocation. Current study examines how relocating colonies respond when the new nest is a limiting resource. Examining this competition across equal sized colonies (n=17) and unequal sized colonies (n=14), we found that most trails had a clear outcome with one of the colonys occupying the new nest, while 25% of colonies merged. Larger colonies had a significantly higher chance of occupying the new nest and outcompeted the smaller colonies in most of the cases. Colonies that had lower latency to discover and more explorers had a significantly higher chance of gaining control of the new nest and interesting the level of aggression shown by both the competing colonies was comparable. Spatio-temporal analysis of the aggression revealed that the area surrounding the old, new nest and the time at which transportation occurs has higher levels of aggression. While both the competing colonies stole pupa from each other, the mean number of successful stealing by the larger colonies was 8 times larger than smaller colonies while stealing was comparable between similar sized colonies. Relocating colonies experienced significantly more mortality as compared to controls and competition for the new nest imposed additional mortality on losing colonies over the short time. Due to the potential merging of colonies, incorporation of stolen brood and increased mortality, the overall fitness of the colonies is likely to be negatively impacted due to intraspecific competition for a new nest.

ecology↗