Ant Trail Research Articles

“Pitfalls” of Bio-Inspired Models on the Example of ant Trails

“Pitfalls” of Bio-Inspired Models on the Example of ant Trails

Ecological principles for the evolution of communication in collective systems.

Communication allows members of a collective to share information about their environment. Advanced collective systems, such as multicellular organisms and social insect colonies, vary in whether they use communication at all and, if they do, in what types of signals they use, but the origins of these differences are poorly understood. Here, we develop a theoretical framework to investigate the evolution and diversity of communication strategies under collective-level selection. We find that whether communication can evolve depends on a collective's external environment: communication only evolves in sufficiently stable environments, where the costs of sensing are high enough to disfavour independent sensing but not so high that the optimal strategy is to ignore the environment altogether. Moreover, we find that the evolution of diverse signalling strategies-including those relying on prolonged signalling (e.g. honeybee waggle dance), persistence of signals in the environment (e.g. ant trail pheromones) and brief but frequent communicative interactions (e.g. ant antennal contacts)-can be explained theoretically in terms of the interplay between the demands of the environment and internal constraints on the signal. Altogether, we provide a general framework for comparing communication strategies found in nature and uncover simple ecological principles that may contribute to their diversity.

Collembola and ants: Influence of trails of red wood ants (Formica lugubris) on the community of soil springtails

Red wood ants are keystone species in forest ecosystems. Because ants are active polyphagous predators, they control the abundance of other arthropods. In addition to direct effects on other species, there are a number of indirect effects caused by ants. In our study, we investigated the influence of ants on springtails, which they rarely come into contact with. Springtails have been set as a model group to assess the state of soil animals, since they are one of the most numerous and widespread groups of soil microarthropods. They are characterized by high sensitivity to environmental changes. The basic characteristics (abundance, species richness, and species diversity) of the springtail community and the response of certain species to the presence of ant trails have been studied. The total abundance and species richness of springtails decreased along ant trails. Among occurred species Parisotoma ParIsotoma notabilis, Lepidacyrtus lignorum, Isotomiella minor, Desoria tigrina, and Pseudasinella alba are the most numerous species both along ant trails and in control samples. There are no significant changes in species diversity (assessed by the Shannon-Weaver index). Species structure of springtail communities along ant trails and in control is different. Two groups of common Collembola species are identified: (1) increasing their numbers in the presence of ants, (2) on the contrary, decreasing. The presence of ants in a forest ecosystem influences the soil springtail community, although ant-Collembola interactions are indirect.

“Pitfalls” of Bio-Inspired Models on the Example of Ant Trails

“Pitfalls” of Bio-Inspired Models on the Example of Ant Trails

“Pitfalls” of Bio-Inspired Models on the Example of Ant Trails

This paper explores the problem of influencing the environment by a group of autonomous robots through the creation and use of road infrastructure. The model object is ant roads (trails). We identify the main aspects of the behavior of different ant species in the process of collective foraging, and actions that together lead to the appearance of a phenomenon that the observer perceives as an ant road. We develop and describe an animat behavior model in the process of arranging a route. We define a list of mechanisms, a set of sensory capabilities, and effectors that are necessary for the robot to implement options for arranging the route. The results of simulation modeling for solving the foraging problem with route clearing are consistent with theoretical models. The simulation results confirm our assumption that the route arrangement can be carried out by individual efforts of animats (robots) and without the need to organize joint actions.

ANALYSIS OF THE SHORTEST ROUTE FROM CIKAMPEK TO PURWOKERTO USING ANT COLONY ALGORITHM

Finding the shortest path sometimes makes most people confused in choosing a path, especially if there are many paths that must be taken to reach one destination. Tracing various routes from Cikampek to Purwokerto is a challenge, with the risk of spending excessive time and money. To solve this problem, this research uses the Ant Colony Algorithm to determine the most efficient path. One of the problems that often arises is that the Cikampek area has 3 routes that can be used to reach Purwokerto, namely the Cikampek - Indramayu (Patrol), Cikampek - Subang, and Cikampek - Bandung routes. The purpose of determining the shortest path is to provide the shortest path solution to users so that they can reach their destination faster and save time and costs. In this study, we use Ant Algorithm because the route from Cikampek to Purwokerto depends on many road factors and other conditions that could change from time to time. For example, traffic congestion and road repairs are major factors. The ant algorithm has strong customization capabilities to determine the shortest path based on the pheromone trails left by ants during exploration. This means that the ant algorithm can work optimally even if there are many factors in road conditions. In addition, the ant algorithm has the ability to handle problems with a large number of nodes, so it can explore various possibilities efficiently. The ant algorithm is an appropriate choice for finding the shortest path in a journey involving complex and diverse routes. There are six steps required to complete the ant algorithm. The first step is initialization, the second step is path selection, and the third step is setting the ant trail and communication between the ants hit by the trail in path selection. The fourth step is to look for visibility, the fifth step is to stop the criterion until it reaches a certain condition, and the last step is to determine the path by calculating probabilities. The results of this study indicate that the ant algorithm can be used to determine the shortest path which is then displayed. This research aims to assist the community in making decisions and determining the location of the city that must be passed. This study took 8 location points with starting point A and destination point H. Based on the results of the discussion it can be concluded that the shortest route from Cikampek to Purwokerto is with 3 routes, namely first (A à D à E à F à H) with a distance of 355 KM, second (A à D à G à F à H) with a distance of 431 KM and the third (A à D à E àH) with a distance of 317 KM.

A stochastic model of ant trail formation and maintenance in static and dynamic environments

Colonies of ants can complete complex tasks without the need for centralised control as a result of interactions between individuals and their environment. Particularly remarkable is the process of path selection between the nest and food sources that is essential for successful foraging. We have designed a stochastic model of ant foraging in the absence of direct communication. The motion of ants is governed by two components - a random change in direction of motion that improves ability to explore the environment, and a non-random global indirect interaction component based on pheromone signalling. Our model couples individual-based off-lattice ant simulations with an on-lattice characterisation of the pheromone diffusion. Using numerical simulations we have tested three pheromone-based model alternatives: (1) a single pheromone laid on the way toward the food source and on the way back to the nest; (2) single pheromone laid on the way toward the food source and an internal imperfect compass to navigate toward the nest; (3) two different pheromones, each used for one direction. We have studied the model behaviour in different parameter regimes and tested the ability of our simulated ants to form trails and adapt to environmental changes. The simulated ants behaviour reproduced the behaviours observed experimentally. Furthermore we tested two biological hypotheses on the impact of the quality of the food source on the dynamics. We found that increasing pheromone deposition for the richer food sources has a larger impact on the dynamics than elevation of the ant recruitment level for the richer food sources.

Spinodal decomposition and phase separation in polar active matter.

We develop and study the hydrodynamic theory of flocking with autochemotaxis. This describes large collections of self-propelled entities all spontaneously moving in the same direction, each emitting a substance which attracts the others (e.g., ants). The theory combines features of the Keller-Segel model for autochemotaxis with the Toner-Tu theory of flocking. We find that sufficiently strong autochemotaxis leads to an instability of the uniformly moving state (the "flock"), in which bands of different density form moving parallel to the mean flock velocity with different speeds. This instability is, therefore, completely different from the well-known "banding instability," in which bands form perpendicular to the mean flock velocity. The bands we find, which are reminiscent of ant trails, coarsen over time to reach a phase-separated state, in which one high-density and one low-density band fill the entire system. The same instability, described by the same hydrodynamic theory, can occur in flocks phase separating due to any microscopic mechanism (e.g., sufficiently strong attractive interactions). Although in many ways analogous to equilibrium phase separation via spinodal decomposition, the two steady-state densities here are determined not by a common tangent construction, as in equilibrium, but by an uncommon tangent construction very similar to that found for motility-induced phase separation of disordered active particles. Our analytic theory agrees well with our numerical simulations of our equationsof motion.

Branched flows in active random walks and the formation of ant trail patterns

Branched flows in active random walks and the formation of ant trail patterns

An alternative host searching strategy found in the subfamily Hybrizontinae (Hymenoptera, Ichneumonidae)

The present study reports the oviposition behavior of the ant parasitoid wasp, Ghilaromma orientalis, on an undescribed ant species from Lasius fuliginosus species group in Japan, illustrated by clear photographs. Previously, the oviposition behavior in the subfamily Hybrizontinae had been limited to species hovering on an ant trail and attacking larvae carried by worker ants. In contrast, in G. orientalis, whose oviposition behavior had not been reported to date, the wasp hung on the grass growing along the ants’ trail by its hind legs with its head down, and when workers with larvae pass by, directed its abdomen toward the larvae with its hind legs remaining on the grass. Our findings suggest that the subfamily Hybrizontinae employs two host-searching strategies—an active strategy previously known and the ambush-type host-searching strategy employed by G. orientalis. The ambush-type strategy affords G. orientalis the advantage of laying eggs in a narrow environment where wasps cannot fly without being noticed by ants. Moreover, by avoiding detection through ambush tactics, wasps are increasing their chance for attack, as ants continue to transport their larvae. However, the search range of wasps is reduced, which may limit the opportunities for parasitization. Additionally, while Lasius nipponensis has been observed as the sole known host of G. orientalis, the oviposition behavior has now been observed in an undescribed species of L. fuliginosus group, suggesting that G. orientalis may have a subgenus-specific host range.

AntTracker: A low-cost and efficient computer vision approach to research leaf-cutter ants behavior

Leaf-cutter ants play a crucial role in agroecosystems, and understanding their behavior is key to developing effective damage control strategies. While several tracking solutions exist for ants in controlled environments or on aerial images, accurately measuring ant behavior in the wild remains a challenge. In this work, we propose a three-stage processing pipeline that segments individual ants, tracks their movement, and classifies whether they are carrying a leaf using a convolutional neural network. The output of the pipeline includes a timestamped record of the activity on the trail, accounting for parameters such as ant velocity, size and if it is going from or to the nest. We use the recently developed portable device AntVideoRecord to register video of a selected ant trail. To validate our approach, we collected a labeled dataset and evaluated each stage using standard metrics, achieving a median F2 score of 83% for segmentation, MOTA of 97% for tracking and F1 of 82% for detecting ants carrying a leaf. We then carried out a larger use case in the wild, demonstrating the effectiveness of our approach in capturing the intricate behaviors of leaf-cutter ants. We believe our method has the potential to inform the development of more effective ant damage control strategies in agroecosystems.

Extension and dynamical phases in random walkers depositing and following chemical trails

Active walker models have proved to be extremely effective in understanding the evolution of a large class of systems in biology like ant trail formation and pedestrian trails. We propose a simple model of a random walker which modifies its local environment that in turn influences the motion of the walker at a later time. We perform direct numerical simulations of the walker in a discrete lattice with the walker actively depositing a chemical which attracts the walker trajectory and also evaporates in time. We propose a method to look at the structural transitions of the trajectory using radius of gyration for finite time walks. The extension over a definite time window shows a non-monotonic change with the deposition rate characteristic of a coil-globule transition. At certain regions of the parameter space of the chemical deposition and evaporation rates, the extensions of the walker shows a re-entrant behavior. The dynamics, characterised by the mean-squared displacement, shows deviation from diffusive scaling at intermediate time scales, returning to diffusive behavior asymptotically. A mean-field theory captures the variation of the asymptotic diffusivity.

Honey bees find the shortest path: a collective flow-mediated approach

Honey bees (Apis mellifera L.) are social insects that makes frequent use of volatile pheromone signals to collectively navigate unpredictable and unknown environments. Ants have been shown to effectively use pheromone trails to find the shortest path between two points, the nest and the food source. The ant pheromone trails are accomplished by depositing pheromones which are then diffused passively, creating isotropic (i.e., non-directional and axi-symmetric) signals. In this study, we report the first instance of the honey bees’ ability to solve the shortest path problem to localize the queen and aggregate around her by using a collective flow-mediated scenting strategy. In this strategy, individual bees not only emit pheromones but also fan their wings to actively direct the flow of the signals, providing colony members with directional messages to the queen’s location. We use computer vision and deep learning approaches to perform automatic and accurate image analysis. As a result, we quantify the number of bees in the short and long paths, and show that the short path is frequented by significantly more bees over time. We also reconstruct attractive surfaces using the positions and directions of scenting bees, and show that this surface is more “attractive” along the short path and around the queen as scenting bees send out directional messages and the swarm makes their way to the queen. Overall, we show that honey bees can effectively use the collective scenting behavior to overcome local and volatile pheromone communication and find the shortest path to the queen.

Wind disrupts trail pheromone communication in the leaf-cutting ant Acromyrmexlobicornis

Although wind is a ubiquitous component of ecological systems and might affect pheromone communication, its effects have not been studied in depth. To test whether wind impacts trail pheromone behaviour, we studied the behaviour of the leaf-cutting ant Acromyrmex lobicornis in natural nests. We conducted observations under (1) unaltered scenarios with different wind intensities and (2) manipulative experiments aimed at altering trail-marking pheromone volatilization rates. In our manipulative experiments, we placed filter paper on ant trails, then removed the pheromone-marked paper 24 h later and either exposed or did not expose the marked paper to artificial wind (2 km/h) for 1 or 3 h. We then put the marked paper back on the trail and filmed ants' responses for 1 min. As controls, we filmed ants’ responses to filter paper immediately before it was removed as well as their responses to new unmarked filter paper. We measured ant flux, speed and walking sinuosity of ants over trails and filter paper, the number of ants tapping their gaster against the substrate (an indication of pheromone-marking frequency), the number of head-on encounters among workers (as alternative modes of communication) and ant body size. Wind negatively affected ant traffic by decreasing ant flux and speed. Colonies increased the number of U-turns and head-on encounters among workers, with a higher response as wind exposure time increased, but trail pheromone deposition was constant among treatments. The size frequency distribution of foragers over the treatment area was skewed towards larger ants on trails with unmarked paper and on trails with paper that had been exposed to wind for 1 or 3 h or not exposed to wind but removed for 3 h. This could be the result of small ants focusing on pheromone trail maintenance, while larger ones focused on foraging on the filter paper irrespective of whether it had been marked. Our results suggest that division of labour and behavioural plasticity might allow leaf-cutting ants to mitigate the effects of wind on pheromone communication and continue foraging. • Wind negatively affected ant traffic on trails by decreasing ant flux and speed. • Ants performed more U-turns and head-on encounters on trails exposed to wind. • Wind exposure did not affect trail pheromone deposition. • Wind exposure influenced the size frequency distribution of forager ants.

Diversity, distribution and secrets of ant transportation networks

One of the most striking examples of transport networks are the trail systems formed and used by several species of ants. Ants forage to find food from a central nest, building a network of trails radiating out to nearby food sources and bring it back to the colony. During the entire tenure of survey 11 ant species trails are encountered in the various locations of study sites. All along, there is a physical contact between the trails of the outgoing and incoming traffics. The way to get back home, after grasping a food load (eggs, larvae, dead carcass of colony members, other invertebrates & vertebrates, sugar cube, plant leaf & seed, piece of bread, etc.) is to follow the up route. In many species such trails are chemically marked by pheromones providing orientation cues for the ants to find their way. Other species count on their faculty of sight and markers as signals. Few opportunistic species like Diacamma scalpratum (Smith), Diacamma vagans (Smith), Tetraponera rufonigra (Jerdon), Tetramorium christiei Forel often abscond themselves in the trail due to search of food. Often only male morphs of few spider species namely Myrmarachne melanocephala MacLeay and Myrmarachne plataleoides O.P.Cambridge are encountered within the ants’ populations in the trail throughout the period of survey. Such a Batesian mimicry exhibited only by the male spiders is possibly an intrinsic escape behaviour from their female mates so as to avoid cannibalism.

Phototactic cyanobacteria as an active matter system

Flocks of birds, schools of fish, mixtures of motors and cytoskeletal filaments, swimming bacteria and driven granular media are systems of interacting motile units that exhibit collective behaviour. These can all be described as active matter systems, since each individual unit takes energy from an internal energy depot and transduces it into work performed on the environment. We review a model for cyanobacterial phototaxis, emphasising the differences from other models for collective behaviour in active matter systems. The interactions between individual cells during phototaxis are dominated by mechanical forces mediated by their physical attachments through type IV pili (T4P) and through the production of “slime”, a complex mixture of non-diffusible polysaccharides deposited by cells that acts to decrease friction locally. The slime, in particular, adds a component to the interaction that is local in space but non-local in time, perhaps most comparable to the pheromones laid down in ant trails. Our results suggest that the time-delayed component of the interactions between bacteria qualify their description as a novel active system, which we refer to as “damp” active matter.

Evolution: Ant trail pheromones promote ant–aphid mutualisms

A new study shows that trail pheromones produced by an invasive ant species suppress the dispersal and stimulate the reproduction of cotton aphids that the ants can 'milk' for honeydew. Aphids use these pheromones as a signal of ant presence and respond adaptively, analogous to early stages of animal husbandry where animals were attracted to human settlements.

Better tired than lost: Turtle ant trail networks favor coherence over short edges.

Creating a routing backbone is a fundamental problem in both biology and engineering. The routing backbone of the trail networks of arboreal turtle ants (Cephalotes goniodontus) connects many nests and food sources using trail pheromone deposited by ants as they walk. Unlike species that forage on the ground, the trail networks of arboreal ants are constrained by the vegetation. We examined what objectives the trail networks meet by comparing the observed ant trail networks with networks of random, hypothetical trail networks in the same surrounding vegetation and with trails optimized for four objectives: minimizing path length, minimizing average edge length, minimizing number of nodes, and minimizing opportunities to get lost. The ants’ trails minimized path length by minimizing the number of nodes traversed rather than choosing short edges. In addition, the ants’ trails reduced the opportunity for ants to get lost at each node, favoring nodes with 3D configurations most likely to be reinforced by pheromone. Thus, rather than finding the shortest edges, turtle ant trail networks take advantage of natural variation in the environment to favor coherence, keeping the ants together on the trails.

Anonychomyrma inclinata sp. nov. (Hymenoptera: Formicidae): description, biology and interaction with the endangered bulloak jewel butterfly, Hypochrysops piceatus Kerr, Macqueen & Sands, 1969 (Lepidoptera: Lycaenidae)

AbstractThe ant Anonychomyrma inclinata sp. nov. is described. It is an arboreal species, nesting in hollows of living mature trees including Allocasuarina luehmannii, Angophora leiocarpa and various Eucalyptus species. Anonychomyrma inclinata can form colonies which are among the most populous recorded for an ant species in Australia, with over 10 000 workers and a total population of 170 000, including all castes. The ant forms extensive trails, forages for insects, collects nectar from a range of flowering plants including many mistletoes and collects honeydew from Hemiptera. The ant's distribution extends from northern inland New South Wales and south central inland Queensland, as far north‐east as Home Hill, on the Burdekin River. The ant is an obligate attendant of the immature stages of the endangered bulloak jewel butterfly, Hypochrysops piceatus Kerr, Macqueen & Sands, 1969, and the southern population of the sapphire azure, Ogyris aenone Waterhouse, 1902. The distribution of A. inclinata is much wider than that currently known for H. piceatus, suggesting that suitable breeding sites may exist for this rare butterfly in areas not previously surveyed. While A. inclinata appears relatively widespread and is able to utilise a wide range of tree species, it is reliant, like H. piceatus, on mature live trees and so is subject to threats including vegetation clearance, timber‐getting, grazing, and increased drought and fire frequency. Due to its critical importance in the life cycle of H. piceatus, any action taken to conserve the butterfly must also consider the importance of preserving healthy populations of A. inclinata.

Moving apart together: co-movement of a symbiont community and their ant host, and its importance for community assembly

BackgroundSpecies interactions may affect spatial dynamics when the movement of one species is determined by the presence of another one. The most direct species-dependence of dispersal is vectored, usually cross-kingdom, movement of immobile parasites, diseases or seeds by mobile animals. Joint movements of species should, however, not be vectored by definition, as even mobile species are predicted to move together when they are tightly connected in symbiont communities.MethodsWe studied concerted movements in a diverse and heterogeneous community of arthropods (myrmecophiles) associated with red wood ants. We questioned whether joint-movement strategies eventually determine and speed-up community succession.ResultsWe recorded an astonishingly high number of obligate myrmecophiles outside red wood ant nests. They preferentially co-moved with the host ants as the highest densities were found in locations with the highest density of foraging red wood ants, such as along the network of ant trails. These observations suggest that myrmecophiles resort to the host to move away from the nest, and this to a much higher extent than hitherto anticipated. Interestingly, functional groups of symbionts displayed different dispersal kernels, with predatory myrmecophiles moving more frequently and further from the nest than detritivorous myrmecophiles. We discovered that myrmecophile diversity was lower in newly founded nests than in mature red wood ant nests. Most myrmecophiles, however, were able to colonize new nests fast suggesting that the heterogeneity in mobility does not affect community assembly.ConclusionsWe show that co-movement is not restricted to tight parasitic, or cross-kingdom interactions. Movement in social insect symbiont communities may be heterogeneous and functional group-dependent, but clearly affected by host movement. Ultimately, this co-movement leads to directional movement and allows a fast colonisation of new patches, but not in a predictable way. This study highlights the importance of spatial dynamics of local and regional networks in symbiont metacommunities, of which those of symbionts of social insects are prime examples.