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Abstract Background Tandem running is a recruitment method found in some species of ants where one ant follows another ant to reach a destination having maintained a physical contact with its antennae, throughout the journey. It is considered that the exchange of information regarding the destination among the nestmates happened during the process of tandem running. We examined the impact of restricting antennal movement on tandem running by using Diacamma indicum, a tandem-running ponerine ant by following 480 tandem runs across 9 treatment colonies and comparing it with 10 control relocating colonies. Result Though all the 19 colonies relocated successfully, treatment colonies took significantly longer time to do so. Restricted antennal movement did not influence the ability to become tandem leaders, initiate tandem runs or the work organization significantly. However, antennae-restricted ants performed fewer tandem runs and took significantly longer time. Followers with single or both antennae-restriction performed significantly higher number of interruptions and the alignment between the leader and follower was impacted as antenna-restricted followers subtended a greater angle and walked more to the side of the leader as compared to the control followers. Conclusion This study showed unhindered movement of the followers’ antennae is important for tandem-running ants. In the next step, to gain a comprehensive understanding of this recruitment method, it is essential to individually delineate different sensory modalities.

IntroductionThe cognitive abilities of animals play a crucial role in their capacity to adapt to changing environments. Experiments to understand cognition are usually performed on animals such as non-human primates, canids, or corvids. These studies often use food as the motivating factor. However, in the current study, we used a new paradigm to investigate the ability of ponerine ants, who are solitary foragers, to solve a nature-inspired problem. As pupae are the most invested brood item and are directly associated with the colony’s fitness, we designed an experiment that presented a challenge to colony relocation by imposing restrictions on the transportation of pupae to the new nest.MethodsWe used a narrow nest entrance through which an adult could enter, but it rendered the passage of an adult holding a pupa virtually impossible. Through this, we examined the capacity of these ants to overcome the “pupal insertion” challenge by investigating eight colonies involving 425 pupal insertions performed by 104 uniquely labeled ants. ResultsWe found that 80% of all pupae were inserted into the nest by employing a novel cooperative behavior: one ant pushed the pupa while the other ant(s) inside the nest pulled it. Even though individual ants showed high variability in their performance regarding pupal insertion, the initial three successive insertions showed a significant improvement in their performance. Such improvement was also documented at the colony level, with shorter durations and fewer attempts for subsequent pupal insertions. DiscussionOur study demonstrated that ants can overcome difficult environmental challenges through innovation and subsequently improve their performance without training or reward.

Ants living in subterranean nests face the challenge of nest flooding and require to combat this recurring issue. The tropical Ponerine ant species, Diacamma indicum , living in simple nests with a single chamber, was used in the current study to examine mound building in the lab. Upon stimulating rain (N = 13 colonies) they built significantly larger nest mounds as compared to controls. Nest mounds proved to be important to colonies that had experienced rain while relocating. Relocating colonies showed significantly higher preference for new nests with mounds (12/13) when choosing between two equidistant, similar quality potential new nests in contrast to control relocations. To the best of our knowledge this study for the first-time documents mound building behaviour in any Ponerine species in laboratory conditions and introduces nest mounds as another architectural feature of interest to relocating colonies. [ABSTRACT FROM AUTHOR]

In the Yucatan Peninsula, the ponerine ant Neoponera villosa nests almost exclusively in tank bromeliads, Aechmea bracteata. In this study, we aimed to determine the factors influencing nest site selection during nest relocation which is regularly promoted by hurricanes in this area. Using ants with and without previous experience of Ae. bracteata, we tested their preference for refuges consisting of Ae. bracteata leaves over two other bromeliads, Ae. bromeliifolia and Ananas comosus. We further evaluated bromeliad-associated traits that could influence nest site selection (form and size). Workers with and without previous contact with Ae. bracteata significantly preferred this species over others, suggesting the existence of an innate attraction to this bromeliad. However, preference was not influenced by previous contact with Ae. bracteata. Workers easily discriminated between shelters of Ae. bracteata and A. comosus, but not those of the closely related Ae. bromeliifolia. In marked contrast, ants discriminated between similar sized Ae. bracteata and Ae. bromeliifolia plants, suggesting that chemical cues and plant structure play an important role. Size was also significant as they selected the largest plant when provided two dissimilar Ae. bracteata plants. Nest site selection by N. villosa workers seems to depend on innate preferences but familiarization with plant stimuli is not excluded.

Colony relocation is an important aspect in the lives of social insects. In ants, the process of relocation is further complicated as brood, in addition to adults, have to be transported to the new nest. Here, we have investigated brood transport in the Indian ponerine ant Diacamma indicum, which uses tandem running-a primitive mode of recruitment-for the entire colony to relocate. We have found that there were no brood transport specialists and most of the brood was transported in the mandibles of followers that were being tandem run. Therefore, in a single tandem run, one adult and one brood item was effectively transported by tandem leaders augmenting the relocation process. [ABSTRACT FROM AUTHOR]

In the Yucatan Peninsula, the ponerine ant Neoponera villosa nests almost exclusively in tank bromeliads, Aechmea bracteata. In this study, we aimed to determine the factors influencing nest site selection during nest relocation which is regularly promoted by hurricanes in this area. Using ants with and without previous experience of Ae. bracteata, we tested their preference for refuges consisting of Ae. bracteata leaves over two other bromeliads, Ae. bromeliifolia and Ananas comosus. We further evaluated bromeliad-associated traits that could influence nest site selection (form and size). Workers with and without previous contact with Ae. bracteata significantly preferred this species over others, suggesting the existence of an innate attraction to this bromeliad. However, preference was not influenced by previous contact with Ae. bracteata. Workers easily discriminated between shelters of Ae. bracteata and A. comosus, but not those of the closely related Ae. bromeliifolia. In marked contrast, ants discriminated between similar sized Ae. bracteata and Ae. bromeliifolia plants, suggesting that chemical cues and plant structure play an important role. Size was also significant as they selected the largest plant when provided two dissimilar Ae. bracteata plants. Nest site selection by N. villosa workers seems to depend on innate preferences but familiarization with plant stimuli is not excluded. [ABSTRACT FROM AUTHOR]