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In ant-aphid interactions, various aphid species offer honeydew to the ant partner and increase their density by ant attendance, whilst others never attend ant species, in which case ants tend to treat them as prey. In this regard, ants should have the ability to distinguish myrmecophile aphid species from non-mutualistic species, so that mutualistic aphids will be accepted as partners rather than prey. Although ant-aphid interactions are now the focus of chemical ecology studies, the role of the different chemical stimuli in determining mutualistic interactions has not been completely clarified. Therefore, we have investigated the cuticular hydrocarbon profile of four myrmecophiles aphid species using GC-MS. We also investigated the behavior of the worker-ants (Lasius niger L., Hymenoptera: Formicidae) to different chemical stimuli derived from aphids. We applied four treatments and found that the behavior of the ant workers varied depending on the source of the different treatments. In particular, the real aphid Aphis pomi and the sugar solution proved to be the most attractive to the ants, while the presence of pure extract of the individuals is enough to disturb the behavior of the ants. We provide evidence that the key stimuli of the tending behavior could be the CHC patterns of the aphids and the CHC profile of the aphids tends to be genus specific. This research will promote further investigations to test the behavior of ant workers towards other species of aphids and treatment combinations. [ABSTRACT FROM AUTHOR]

Since Tinbergen’s seminal contribution in 1963, ethology has blossomed as a multifaceted research field. Sixty years later, uncountable articles followed the four questions proposed as necessary for understanding animal behaviour, and they culminated in the segmentation of subareas which communicate little among themselves. Foraging in ants is one example where this division happened, despite the clear need to integrate results obtained from different approaches. We chose this research subject to revise the literature, relating the main results to the relevant level of explanation in Tinbergen’s four questions theoretical framework. Through such revision, we aim to foster the integration of different approaches and to bring to light how this can clarify how we understand foraging behaviour, sixty years after Tinbergen’s initial proposition. [ABSTRACT FROM AUTHOR]

Ant colony optimization (ACO) is a stochastic optimization algorithm inspired by the foraging behavior of ants. We investigate a simplified computational model of ACO, wherein ants sequentially engage in binary decision-making tasks, leaving pheromone trails contingent upon their choices. The quantity of pheromone left is the number of correct answers. We scrutinize the impact of a salient parameter in the ACO algorithm, specifically, the exponent α , which governs the pheromone levels in the stochastic choice function. In the absence of pheromone evaporation, the system is accurately modeled as a multivariate nonlinear Pólya urn, undergoing phase transition as α varies. The probability of selecting the correct answer for each question asymptotically approaches the stable fixed point of the nonlinear Pólya urn. The system exhibits dual stable fixed points for α ≥ α c and a singular stable fixed point for α < α c where α c is the critical value. When pheromone evaporates over a time scale τ , the phase transition does not occur and leads to a bimodal stationary distribution of probabilities for α ≥ α c and a monomodal distribution for α < α c . [ABSTRACT FROM AUTHOR]

Sol g 2 is the major protein in Solenopsis geminata fire ant venom. It shares the highest sequence identity with Sol i 2 (S. invicta) and shares high structural homology with LmaPBP (pheromone-binding protein (PBP) from the cockroach Leucophaea maderae). We examined the specific Sol g 2 protein ligands from fire ant venom. The results revealed that the protein naturally formed complexes with hydrocarbons, including decane, undecane, dodecane, and tridecane, in aqueous venom solutions. Decane showed the highest affinity binding (Kd) with the recombinant Sol g 2.1 protein (rSol g 2.1). Surprisingly, the mixture of alkanes exhibited a higher binding affinity with the rSol g 2.1 protein compared to a single one, which is related to molecular docking simulations, revealing allosteric binding sites in the Sol g 2.1 protein model. In the trail-following bioassay, we observed that a mixture of the protein sol g 2.1 and hydrocarbons elicited S. geminata worker ants to follow trails for a longer time and distance compared to a mixture containing only hydrocarbons. This suggests that Sol g 2.1 protein may delay the evaporation of the hydrocarbons. Interestingly, the piperidine alkaloids extracted have the highest attraction to the ants. Therefore, the mixture of hydrocarbons and piperidines had a synergistic effect on the trail-following of ants when both were added to the protein. [ABSTRACT FROM AUTHOR]

Here we describe the diversity of the Malagasy Nesomyrmex brevicornis-group as the final installment of series describing the complete Malagasy Nesomyrmex fauna. In the current paper introduce the N. brevicornis-group, a newly outlined species group. We split this group from one of the four former groups, N. madecassus-group (sensu Csősz and Fisher 2015). The relatively small number of individuals available within the N. brevicornis-group relative to the large number of OTUs hampers the use of sophisticated statistical techniques to evaluate the morphological data. Instead, we assess the diversity of the N. brevicornis-group via a conventional morphology-based approach relying upon non-numeric characters (shape, sculpture, color etc.) recorded by simple eye inspection. Morphometric data are used as secondary data to confirm the most probable boundaries between species, but without employing statistical analyses. We rejected prior species hypotheses imposed by the primary approach if a non-overlapping range of a single index calculated from continuous numeric traits was found between two hypothesized species. Our methods render every species in this revisionary work separable via both salient features and morphometric traits. Our approach reveals the existence of nine morphologically distinct species, Nesomyrmex brevicornis sp. n., N. brunneus sp. n., N. cingulatus sp. n., N. edentates sp. n., N. flavigaster sp. n., N. longiceps sp. n., N. minutus sp. n., N. punctaticeps sp. n., and N. sellaris sp. n.. Geographic maps showing the distribution of each species are provided, along with an updated key to workers of Malagasy Nesomyrmex species groups that includes the newly outlined N. brevicornis-group. [ABSTRACT FROM AUTHOR]

It is well established that danger information can be transmitted by ants through relatively small distances, provoking either a state of alarm when they move away from potentially dangerous stimulus, or charge toward it aggressively. There is almost no knowledge if danger information can be transmitted along large distances. In this paper, we abduct leaf cutting ants of the species Atta insularis while they forage in their natural environment at a certain point of the foraging line, so ants make a 'U' turn to escape from the danger zone and go back to the nest. Our results strongly suggest that those ants do not transmit 'danger information' to other nestmates marching towards the abduction area. The individualistic behavior of the ants returning from the danger zone results in a depression of the foraging activity due to the systematic sacrifice of non-informed individuals. [ABSTRACT FROM AUTHOR]

The Saharan silver ant Cataglyphis bombycina is one of the terrestrial living organisms best adapted to tolerate high temperatures. It has recently been shown that the hairs covering the ant’s dorsal body part are responsible for its silvery appearance. The hairs have a triangular cross-section with two corrugated surfaces allowing a high optical reflection in the visible and near-infrared (NIR) range of the spectrum while maximizing heat emissivity in the mid-infrared (MIR). Those two effects account for remarkable thermoregulatory properties, enabling the ant to maintain a lower thermal steady state and to cope with the high temperature of its natural habitat. In this paper, we further investigate how geometrical optical and high reflection properties account for the bright silver color of C. bombycina. Using optical ray-tracing models and attenuated total reflection (ATR) experiments, we show that, for a large range of incidence angles, total internal reflection (TIR) conditions are satisfied on the basal face of each hair for light entering and exiting through its upper faces. The reflection properties of the hairs are further enhanced by the presence of the corrugated surface, giving them an almost total specular reflectance for most incidence angles. We also show that hairs provide an almost 10-fold increase in light reflection, and we confirm experimentally that they are responsible for a lower internal body temperature under incident sunlight. Overall, this study improves our understanding of the optical mechanisms responsible for the silver color of C. bombycina and the remarkable thermoregulatory properties of the hair coat covering the ant’s body. [ABSTRACT FROM AUTHOR]

In ants, nutrient acquisition for the whole colony relies on a minority of workers, the foragers, which are often old and lean. Some studies have shown that the link between age, physiology and foraging activity is more flexible than once thought, especially in response to colony or environmental perturbations. This great plasticity offers the intriguing possibility to disentangle the effect of age, behaviour and physiology on the ants' abilities to cope with nutritional stresses. In this paper, we first looked at the capacity of groups of foragers and inner-nest workers to resist starvation and macronutrient imbalance. Second, we investigated whether behavioural task reversion modified the tolerance to nutritional stresses and by extension, changed mortality rate. We found that inner-nest workers live longer than foragers under nutritional stresses but not under optimal conditions. The reversion from foraging to inner-nest activities is followed by an increase in fat content and longevity. Finally, we demonstrated that changes in fat content associated with behavioural transition are highly flexible and strongly correlated to tolerance of nutritional stress. Our results have considerable implications for our understanding of the population dynamics of social insects under adverse nutritional conditions. [ABSTRACT FROM AUTHOR]

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Dynamic time warping (DTW) is a classical similarity measure for arbitrary length time series. As an effective improvement of DTW, dynamic time warping under limited warping path length (LDTW) oppresses the long-term pathological alignment problem and allows better exibility. However, since LDTW increases path lengths, it directly leads to higher time-consuming. In this paper, a new method of similarity sequence measurement (ACO LDTW) is proposed by the parallel computing characteristics of ant colony optimization (ACO) algorithm with bio-inspired strategy and the idea of LDTW path restriction. This algorithm searches the optimal path on the restricted distance matrix by simulating the behavior of ant colony parallel foraging. Firstly, the distance matrix is mapped to the 0 - 1 matrix of grid method, and the search range of ants is limited by the warping path in LDTW. Secondly, the state transition probability function, pheromone initialization and update mechanism of ACO algorithm are adapted. On the basis of ensuring the accurate results, the convergence rate can be effectively improved. The validity of ACO LDTW is verified by cases. In the 22 data sets of 1NN classification experiment, ACO LDTW has the lowest classification error rate in 16 data sets, and it is shorter than the calculation time of LDTW. At the same time, it is applied to the field of mechanical fault diagnosis and has the ability to solve practical engineering applications. Experiments show that ACO LDTW is more effective in terms of accuracy and computation time. [ABSTRACT FROM AUTHOR]

Honey bees (genus Apis) are well known for the impressive suite of nest defenses they have evolved to protect their abundant stockpiles of food and the large colonies they sustain. In Asia, honey bees have evolved under tremendous predatory pressure from social wasps in the genus Vespa, the most formidable of which are the giant hornets that attack colonies in groups, kill adult defenders, and prey on brood. We document for the first time an extraordinary collective defense used by Apis cerana against the giant hornet Vespa soror. In response to attack by V. soror, A. cerana workers foraged for and applied spots of animal feces around their nest entrances. Fecal spotting increased after colonies were exposed either to naturally occurring attacks or to chemicals that scout hornets use to target colonies for mass attack. Spotting continued for days after attacks ceased and occurred in response to V. soror, which frequently landed at and chewed on entrances to breach nests, but not Vespa velutina, a smaller hornet that rarely landed at entrances. Moderate to heavy fecal spotting suppressed attempts by V. soror to penetrate nests by lowering the incidence of multiple-hornet attacks and substantially reducing the likelihood of them approaching and chewing on entrances. We argue that A. cerana forages for animal feces because it has properties that repel this deadly predator from nest entrances, providing the first report of tool use by honey bees and the first evidence that they forage for solids that are not derived from plants. Our study describes a remarkable weapon in the already sophisticated portfolio of defenses that honey bees have evolved in response to the predatory threats they face. It also highlights the strong selective pressure honey bees will encounter if giant hornets, recently detected in western North America, become established. [ABSTRACT FROM AUTHOR]

In this paper, we present a generic theoretical chemotactic model that accounts for certain emergent behaviors observed in ant foraging. The model does not have many of the constraints and limitations of existing models for ants colony dynamics and takes into account the distinctly different behaviors exhibited in nature by ant foragers in search of food and food ferrying ants. Numerical simulations based on the model show trail formation in foraging ant colonies to be an emergent phenomenon and, in particular, replicate behavior observed in experiments involving the species P. megacephala. The results have broader implications for the study of randomness in chemotactic models. Potential applications include the developments of novel algorithms for stochastic search in engineered complex systems such as robotic swarms. [ABSTRACT FROM AUTHOR]

The symmetry breaking observed in nature is fascinating. This symmetry breaking is observed in both human crowds and ant colonies. In such cases, when escaping from a closed space with two symmetrically located exits, one exit is used more often than the other. Group size and density have been reported as having no significant impact on symmetry breaking, and the alignment rule has been used to model symmetry breaking. Density usually plays important roles in collective behavior. However, density is not well-studied in symmetry breaking, which forms the major basis of this paper. The experiment described in this paper on an ant colony displays an increase then decrease of symmetry breaking versus ant density. This result suggests that a Vicsek-like model with an alignment rule may not be the correct model for escaping ants. Based on biological facts that ants use pheromones to communicate, rather than seeing how other individuals move, we propose a simple yet effective alarm pheromone model. The model results agree well with the experimental outcomes. As a measure, this paper redefines symmetry breaking as the collective asymmetry by deducing the random fluctuations. This research indicates that ants deposit and respond to the alarm pheromone, and the accumulation of this biased information sharing leads to symmetry breaking, which suggests true fundamental rules of collective escape behavior in ants. [ABSTRACT FROM AUTHOR]

The technology of self-driving cars will inevitably change the industry of taxis and ride-sharing cars that provide important commercial ground transportation services to travelers, tourists and local residents. There is no doubt that new techniques, business models and strategies will be needed to follow the use of selfdriving cars. This paper focuses on a forward-looking research topic that route commercial, vacant self-driving vehicles so that the values to both businesses and passengers are improved. Importance of solutions to the new problem is discussed. We also propose a novel design which simulates behaviors of ants in nature to the vehicles. The goal of the system is to obtain an overall balance between the demands of using the services from the passengers and availability of the vehicles in all service areas. The system not only uses historical data to make decisions, it also responds promptly for demands appeared dynamically. [ABSTRACT FROM AUTHOR]

This paper uses a nature inspired metaheuristic algorithm based on the behavior of ant lions named as Ant Lion Optimization (ALO) to design the fractional order PID controller (FOPID) for controlling first order and higher order systems. The ALO is used to optimize the parameters of the FOPID controllers. This algorithm is based upon the hunting behavior of ant lions which is described by five important phases of hunting the ants: random walk, building trap, entrapments of ants in traps, sliding ants towards the antlion, catching the prey and rebuild the trap. ALO algorithm based fractional order PID controller is proposed for delay system and also for higher order system. To obtain the optimal computation, different performance indices such as IAE (Integral Absolute Error), ISE (Integral Squared Error), ITAE (Integral Time Absolute Error), ITSE (Integral Time Squared Error) are considered for the optimization. As the delay system exhibits non-minimum phase characteristic, to improve gain and phase margin, the ALO based fractional order PID is optimally designed by considering different objective functions such as IAE, ISE, ITAE and ITSE. All the simulations are carried out in Simulink/Matlab environment. The proposed method has superiority value in terms of transient and frequency responses as compared with other methods, which has been demonstrated by illustrative examples. [ABSTRACT FROM AUTHOR]

Although the Neotropical territorially dominant arboreal ant Azteca chartifex Forel is very aggressive towards any intruder, its populous colonies tolerate the close presence of the fierce polistine wasp Polybia rejecta (F.). In French Guiana, 83.33% of the 48 P. rejecta nests recorded were found side by side with those of A. chartifex. This nesting association results in mutual protection from predators (i.e., the wasps protected from army ants; the ants protected from birds). We conducted field studies, laboratory‐based behavioral experiments and chemical analyses to elucidate the mechanisms allowing the persistence of this association. Due to differences in the cuticular profiles of the two species, we eliminated the possibility of chemical mimicry. Also, analyses of the carton nests did not reveal traces of marking on the envelopes. Because ant forager flows were not perturbed by extracts from the wasps' Dufour's and venom glands, we rejected any hypothetical action of repulsive chemicals. Nevertheless, we noted that the wasps "scraped" the surface of the upper part of their nest envelope using their mandibles, likely removing the ants' scent trails, and an experiment showed that ant foragers were perturbed by the removal of their scent trails. This leads us to use the term "erasure hypothesis." Thus, this nesting association persists thanks to a relative tolerance by the ants towards wasp presence and the behavior of the wasps that allows them to "contain" their associated ants through the elimination of their scent trails, direct attacks, "wing‐buzzing" behavior and ejecting the ants. [ABSTRACT FROM AUTHOR]

The article presents the discussion on representations being inspired by the traditional arts. Topics include useful silkworms, beautiful butterflies, mysterious fireflies, ants, as well as intrusive flies, danger spiders; and showing the reasons of contemporary artists incorporating insects and spiders in the artwork.

Combinatorial optimization challenges are rooted in real-life problems, continuous optimization problems, dis- crete optimization problems and other significant problems in telecommunications which include, for example, routing, de- sign of communication networks and load balancing. Load balancing applies to distributed systems and is used for man- aging web clusters. It allows to forward the load between web servers, using several scheduling algorithms. The main motivation for the study is the fact that combinatorial op- timization problems can be solved by applying optimization algorithms. These algorithms include ant colony optimiza- tion (ACO), honey bee (HB) and multi-objective optimization (MOO). ACO and HB algorithms are inspired by the foraging behavior of ants and bees which use the process to locate and gather food. However, these two algorithms have been sug- gested to handle optimization problems with a single-objective. In this context, ACO and HB have to be adjusted to multi- objective optimization problems. This paper provides a sum- mary of the surveyed optimization algorithms and discusses the adaptations of these three algorithms. This is pursued by a detailed analysis and a comparison of three major schedul- ing techniques mentioned above, as well as three other, new algorithms (resulting from the combination of the aforemen- tioned techniques) used to effciently handle load balancing issues. [ABSTRACT FROM AUTHOR]

Ant workers are often specialized in specific tasks, and it is well‐established that the main task an ant performs in the colony can be used to predict its sensitivity and responses to task‐associated stimuli. An often‐overlooked aspect of ants' task specialization is that individuals often switch tasks throughout the day and are not always engaged in functional tasks. Furthermore, the tasks individuals engage in are often correlated with other context‐specific factors, such as worker density, which can independently influence individuals' behaviour. Given this intra‐individual variation in task engagement and its correlation with density, it is currently unknown how these two factors interact to modulate ants' sensitivity and responses to stimuli.To address this question, we built a robotic manipulation system that allowed us to teleoperate a dummy inside ant colonies and to provide simulated antennations to ants when performing different tasks in areas with different worker densities. We coupled this manipulation system with a custom‐built automated tracking system (FORT) that allowed us to track individual identities and locations as well as to record the ants' responses to the dummy stimulation.We found independent effects of task and worker density on ants' responsiveness and alarm towards the dummy. Ants were less likely to respond and be alarmed by the dummy when stimulated in areas with high worker density. Responsiveness but not alarm was further influenced by the task being performed, with ants doing broodcare being the least responsive. Our results suggest that ants' behaviour is density‐dependent and that ants experience a process of habituation to tactile stimulation. Additionally, ants' responsiveness is modulated by the task they are performing at a given time, showing that sensitivity to stimuli is context‐dependent.Our robotic set‐up constitutes a valuable tool to systematically investigate social insect behaviour under unprecedented experimental control to unravel the individual‐level behavioural rules that underpin the organization of social insect colonies. The integrated system presented here opens new research avenues to empirically investigate the effects of more complex stimuli on social insect behaviour and has the potential to significantly further our understanding of decentralized collective systems. [ABSTRACT FROM AUTHOR]

Simple Summary: Solenopsis invicta (Hymenoptera: Formicidae), also known as the red imported fire ant, is a social insect and a worldwide invasive pest. Biochar is a widely used soil amendment. In this work, we investigated the effects of varying soil biochar levels on irritability and contact toxicity as well as the behavioral and physiological changes in red fire ant behavior. High doses of biochar were toxic and repulsive to red fire ants, impairing their ability to walk, grasp, attack, and gather while also causing an increase in the activity of enzymes associated with oxidative stress. This study supports the prudent utilization of biochar as well as the prevention and management of red fire ants. Solenopsis invicta, often known as the red imported fire ants (RIFAs), is a well-known global invasive ant species that can be found in agricultural, urban, and natural environments worldwide. Simultaneously, it also inhabits the soil. Biochar is generated by the pyrolysis of organic matter under high-temperature anoxic environments and widely used in agricultural ecosystems and soil amendment. However, to date, it remains unknown as to whether soil application of biochar has a negative effect on RIFAs. In our study, we investigated the toxicity and irritability effects of different amounts of biochar (0%, 1%, 2%, 5%, 10%, and 20%) introduced into the soil on red fire ants; upon comparison with the control soil (0% biochar), the application of 1%, 2%, and 5% biochar did not result in significantly different results. But the utilization of biochar at a concentration over 10% effectively repelled the RIFAs, resulting in their departure from the treated soils. High doses of biochar were able to cause death of red fire ants; the mortality rate of red fire ants reached 55.56% after 11 days of 20% biochar treatment. We also evaluated the effects of biochar on four behaviors of red fire ants, namely aggregation, walking, grasping, and attacking; 20% of the biochar treatment group reduced aggregation by 64.22% and this value was 55.22%, 68.44%, and 62.36% for walking, grasping, and attacking. Finally, we measured the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) enzyme activity and malondialdehyde (MDA) content in red fire ants; the results showed that the activities of the three enzymes increased with the increase in biochar addition, which indicated that a high dose of biochar induced oxidative stress in red fire ants. Our results indicate that biochar has the potential to cause toxicity and repel red imported fire ants (RIFAs) in a manner that is dependent on the concentration. We propose that biochar could be utilized in the control and manufacturing of baits for red fire ant management. This work establishes a foundation for the prevention and management of red fire ants and the logical utilization of biochar. [ABSTRACT FROM AUTHOR]

The common sand-dwelling Formica cinerea ants possess monomorphic workers, yet with considerable and easily identified size variation. Considering the importance of body size in polymorphic ants and other animals, we test whether size-dependent differences in behaviour occur in this species. We focus on the behaviour of large and small foragers in the context of rescue occurring between nestmates when one of them is entrapped and requires help. We show that workers of different sizes are characterized by a similar frequency of rescue activity and time delay to the first act of rescue. However, small workers rescue for longer than large workers. These results indicate that, although there is no size-related rescue specialization in F. cinerea foragers, small rescuers behave differently than large ones in terms of rescue persistence. Additionally, we show that small workers are more active when trapped. We suggest that variation in behavioural persistence of differently-sized workers may increase the efficiency of rescue actions. This study is the first to find a connection between body size and rescue behaviour in ants and the first to quantify and analyze the behaviour of individuals in need of rescue. These findings add substantially to our understanding of social insects and, more generally, highlight the need to study among-individual behavioural variation in social animals, including those in which body size is judged minute and irrelevant. [ABSTRACT FROM AUTHOR]

Ants store and recall views associated with foraging success, facilitating future foraging journeys. Negative views are also learned, but instead prompt avoidance behaviors such as turning away. However, little is known about the aversive view's role in navigation, the effect of cue conflict, or the contextual relationship between learning and recalling. In this study, we tested Myrmecia midas' capacity for aversive learning of views either independently of or in conflict with appetitive events. We either captured and released foragers when reaching a location or let them pass unhindered. After a few journeys, captured foragers exhibited aversive learning by circumventing the capture location and increasing both meandering and scanning. Ants that experienced foraging-appetitive and homing-aversive events on their journeys exhibited lower rates of avoidance behavior and scans than those experiencing aversive events in both outbound and homebound journeys. The foraging-aversive and homing-aversive ants exhibited similar levels of avoidance and scanning as those that experienced the foraging-aversive and homing-appetitive. We found that foragers showed evidence of context specificity in their scanning behavior, but not in other measures of aversive learning. The foragers did not increase their meandering and scans while approaching the views associated with aversive events. In addition to shedding light on the role of aversive views in navigation, our finding has important implications for understanding the learning mechanisms triggered by handling animals. [ABSTRACT FROM AUTHOR]

When foraging, internal needs for particular nutrients might affect food choice, and external constraints, such as predation risk, might impact trade-offs between foraging and risk avoidance. Examining both internal and external constraints simultaneously can provide important insights into how animals make decisions. We examined how internal nutritional needs and external cues of mortality risk jointly impact the foraging behavior of ants. Ant colonies require carbohydrates to support workers energetically and proteins to raise brood. Furthermore, colonies adjust their foraging activity in response to the environment, such as food availability and the presence of predators or heterospecifics. Here we examine the foraging decisions of groups of Argentine ants Linepithema humile , which differ in their nutritional needs in high-risk environments. We starved groups of ants for either proteins or carbohydrates and determined the foraging choices that ants made when cues of heterospecifics were present. We found that ants preferentially forage for carbohydrates in high-risk conditions. Furthermore, starvation for carbohydrates increased the ants' preference for carbohydrates, even when cues of heterospecifics were present at both carbohydrates and protein resources. Starvation for protein also resulted in preferential foraging for carbohydrates, but it increased visitation to a protein food source in high-risk environments compared to when ants were starved for carbohydrates or for both resources. Examining the effect of both nutrition and mortality risk on foraging simultaneously provides insights about state-dependent risk-taking behavior that may have important implications for predicting the invasion of species into novel habitats. [ABSTRACT FROM AUTHOR]

Hepatic encephalopathy (HE) implies high morbidity and mortality. The assessment of covert HE (CHE) [i.e. minimal HE (MHE) plus grade 1 HE] is often neglected in Taiwan. Therefore, the aim was to investigate the potential of the animal naming test (ANT1 and simplified ANT1 (S-ANT1)) for assessing CHE in Chinese-speaking regions, specifically Taiwan. A prospective cohort study was conducted, comprising 65 cirrhotic patients and 29 healthy controls (relatives of the patients). Patients were followed up every three months and censored after two years or until death. Hospitalization for overt HE (OHE) and mortality were considered. All subjects underwent ANT1, psychometric HE score (PHES), and mini-mental state examination (MMSE). The patients underwent an electroencephalogram (EEG) to detect slowing indicative of MHE. Cut-off values for ANT1 and S-ANT1 were assessed by ROC analysis and Youden's index, considering CHE as a reference. The prognostic values for OHE and OHE-free survival were assessed. Preliminary analysis confirmed that PHES ≤-4 is a good discriminant point for abnormal results. CHE was found in 29 patients: 9 had MHE (PHES ≤ -4 or altered EEG) and 20 had grade 1 HE. ANT1 and S-ANT1 were found to have diagnostic values for CHE: AUC = 0.807, 0.786; cut off: 18 and 19, respectively. ANT1 and S-ANT1 were found to have prognostic value for OHE, number of hospitalization episodes for OHE, and OHE recurrence-free survival. ANT1 shows promise as a tool for CHE detection, quantification, and follow-up in Taiwan and other Chinese-speaking regions. The animal naming test (ANT1) is a simple and valid semantic fluency test that can be easily performed in outpatient or bedside settings in one minute and can also be used as a tool for covert hepatic encephalopathy (CHE) detection, quantification, and follow-up in Taiwan, other Chinese-speaking regions, and many other countries. The diagnostic value of ANT1 and S-ANT1 for CHE were found to be significant, with area under the receiver operating characteristic curve (AUROC) values of 0.807 and 0.786 respectively, and cut-off scores of 18 and 19. ANT1 and S-ANT1 have prognostic value for the first breakthrough of overt hepatic encephalopathy (OHE), number of hospitalization episodes for OHE, and OHE recurrence-free survival, independent of the MELD score. [ABSTRACT FROM AUTHOR]

The study of the foraging behavior of group animals (especially ants) is of practical ecological importance, but it also contributes to the development of widely applicable optimization problem-solving techniques. Biologists have discovered that single ants exhibit lowdimensional deterministic-chaotic activities. However, the influences of the nest, ants' physical abilities, and ants' knowledge (or experience) on foraging behavior have received relatively little attention in studies of the collective behavior of ants. This paper provides new insights into basic mechanisms of effective foraging for social insects or group animals that have a home. We propose that the whole foraging process of ants is controlled by three successive strategies: hunting, homing, and path building. A mathematical model is developed to study this complex scheme. We show that the transition from chaotic to periodic regimes observed in our model results from an optimization scheme for group animals with a home. According to our investigation, the behavior of such insects is not represented by random but rather deterministic walks (as generated by deterministic dynamical systems, e.g., by maps) in a random environment: the animals use their intelligence and experience to guide them. The more knowledge an ant has, the higher its foraging efficiency is.When young insects join the collective to forage with old and middle-aged ants, it benefits the whole colony in the long run. The resulting strategy can even be optimal. [ABSTRACT FROM AUTHOR]

In Shapotou, northeast of the Tengger Desert in China, Formica cunicularia Lat. proliferated after mobile sand dune stabilization by artificial revegetation. In the present paper, the anthill properties of F. cunicularia after sand stabilization were systematically investigated along a chronosequence. The soil properties and soil seed banks in the anthill and adjacent soils without anthills were also examined. The results showed that the revegetation age, landform, and their interactions significantly affected the anthill density, anthill coverage, and soil turnover capacity of F. cunicularia. The longer the dunes were stabilized, the more ant nests proliferated in the dunes. More nests were located in the hollow and windward slopes than in the dune top and leeward slopes. Soil organic matter, total and available N, P, and K, electrical conductivity, as well as soil water content were all significantly higher in the nests than in the adjacent soils without anthills. The soil seed bank in the anthill was much greater than in the adjacent soil for both moss- and algal-crusted soils. The current research suggested that the occurrence of F. cunicularia after mobile sand dune stabilization greatly influenced both soil properties and soil seed bank. [ABSTRACT FROM PUBLISHER]

A wide range of group-living animals construct tangible infrastructure networks, often of remarkable size and complexity. In ant colonies, infrastructure construction may require tens of thousands of work hours distributed among many thousand individuals. What are the individual behaviours involved in the construction and what level of complexity in inter-individual interaction is required to organize this effort? We investigate this question in one of the most sophisticated trail builders in the animal world: the leafcutter ants, which remove leaf litter, cut through overhangs and shift soil to level the path of trail networks that may cumulatively extend for kilometres. Based on obstruction experiments in the field and the laboratory, we identify and quantify different individual trail clearing behaviours. Via a computational model, we further investigate the presence of recruitment, which--through direct or indirect information transfer between individuals--is one of the main organizing mechanisms of many collective behaviours in ants. We show that large-scale transport networks can emerge purely from the stochastic process of workers encountering obstructions and subsequently engaging in removal behaviour with a fixed probability. In addition to such incidental removal, we describe a dedicated clearing behaviour in which workers remove additional obstructions independent of chance encounters. We show that to explain the dynamics observed in the experiments, no information exchange (e.g. via recruitment) is required, and propose that large-scale infrastructure construction of this type can be achieved without coordination between individuals. [ABSTRACT FROM AUTHOR]

Ants are generally believed to follow an intensive work routine. Numerous tales and fables refer to ants as conscientious workers. Nevertheless, biologists have discovered that ants also rest for extended periods of time. This does not only hold for individual ants. Interestingly, ant colonies exhibit synchronized activity phases that result from self-organization. In this work, self-synchronization in ant colonies is taken as the inspiring source for a new mechanism of self-synchronized duty-cycling in mobile sensor networks. Hereby, we assume that sensor nodes are equipped with energy harvesting capabilities such as, for example, solar cells. We show that the proposed self-synchronization mechanism can be made adaptive depending on variable energy resources. The main objective of this paper is to study and explore the swarm intelligence foundations of self-synchronized duty-cycling. With this purpose in mind, physical constraints such as packet collisions and packet loss are generally not considered. [ABSTRACT FROM AUTHOR]

Although helping behavior is ubiquitous throughout the animal kingdom, actual rescue activity is particularly rare. Nonetheless, here we report the first experimental evidence that ants, Cataglyphis cursor, use precisely directed rescue behavior to free entrapped victims; equally important, they carefully discriminate between individuals in distress, offering aid only to nestmates. Our experiments simulate a natural situation, which we often observed in the field when collecting Catagyphis ants, causing sand to collapse in the process. Using a novel experimental technique that binds victims experimentally, we observed the behavior of separate, randomly chosen groups of 5 C. cursor nestmates under one of six conditions. In five of these conditions, a test stimulus (the ''victim'') was ensnared with nylon thread and held partially beneath the sand. The test stimulus was either (1) an individual from the same colony; (2) an individual from a different colony of C cursor; (3) an ant from a different ant species; (4) a common prey item; or, (5) a motionless (chilled) nestmate. In the final condition, the test stimulus (6) consisted of the empty snare apparatus. Our results demonstrate that ants are able to recognize what, exactly, holds their relative in place and direct their behavior to that object, the snare, in particular. They begin by excavating sand, which exposes the nylon snare, transporting sand away from it, and then biting at the snare itself. Snare biting, a behavior never before reported in the literature, demonstrates that rescue behavior is far more sophisticated, exact and complexly organized than the simple forms of helping behavior already known, namely limb pulling and sand digging. That is, limb pulling and sand digging could be released directly by a chemical call for help and thus result from a very simple mechanism. However, it's difficult to see how this same releasing mechanism could guide rescuers to the precise location of the nylon thread, and enable them to target their bites to the thread itself. [ABSTRACT FROM AUTHOR]

In this paper, a novel swarm intelligent algorithm is proposed called ant nesting algorithm (ANA). The algorithm is inspired by Leptothorax ants and mimics the behavior of ants searching for positions to deposit grains while building a new nest. Although the algorithm is inspired by the swarming behavior of ants, it does not have any algorithmic similarity with the ant colony optimization (ACO) algorithm. It is worth mentioning that ANA is considered a continuous algorithm that updates the search agent position by adding the rate of change (e.g., step or velocity). ANA computes the rate of change differently as it uses previous, current solutions, fitness values during the optimization process to generate weights by utilizing the Pythagorean theorem. These weights drive the search agents during the exploration and exploitation phases. The ANA algorithm is benchmarked on 26 well-known test functions, and the results are verified by a comparative study with genetic algorithm (GA), particle swarm optimization (PSO), dragonfly algorithm (DA), five modified versions of PSO, whale optimization algorithm (WOA), salp swarm algorithm (SSA), and fitness dependent optimizer (FDO). ANA outperformances these prominent metaheuristic algorithms on several test cases and provides quite competitive results. Finally, the algorithm is employed for optimizing two well-known real-world engineering problems: antenna array design and frequency-modulated synthesis. The results on the engineering case studies demonstrate the proposed algorithm's capability in optimizing real-world problems. [ABSTRACT FROM AUTHOR]

1. The major aim of this paper was to explore the mechanistic basis of induced defensive ant response in myrmecophytic Piper species and their ant-partner Pheidole bicornis by combining experimental trials and chemical analysis. 2. In field experiments, the response of Pheidole ants to simulated stem-damage of their host plant was documented. Their reaction to other myrmecophytic and non-myrmecophytic Piper species was explored by fixing respective stem sections onto inhabited Piper fimbriulatum individuals. After artificial damage to stems of P. fimbriulatum and stem sections from other myrmecophytic Piper, the number of ants increased to a maximum of 63 individuals on the damaged internode within the first 10 min. By contrast, no or only a poor reaction was elicited by stem sections from the selected non-myrmecophytic Piper species. 3. Solid-phase microextraction/gas chromatography–mass spectrometry identified 68 volatile organic compounds (VOCs) which were emitted from wounded stem bark of three myrmecophytic ( P. fimbriulatum, P. obliquum, P. sagittifolium) and two non-myrmecophytic ( P. hispidum, P. riparense) Piper species, comprising monoterpenes, sesquiterpenes, simple aromatic compounds, and green leaf volatiles (GLVs, oxylipins). Despite considerable variation in the VOC profiles, an analysis of similarities (anosim) classified the accumulation of the sesquiterpenes β-caryophyllene, germacrene D and emission of the oxylipin reactive electrophilic species (RES) compounds hexanal, cis-3-hexene-1-ol, 2-hexenal, 2-undecanone and 1-hexanol as characteristic of the myrmecophytic species. 4. Synthesis. Field experiments showed that mechanical disturbance of myrmecophytic Piper stems is not sufficient to elicit recruitment and alertness of the ant-partner Ph. bicornis, but that specific volatiles released from the host plant are responsible. Analyses of the VOCs identified after simulated stem damage of three myrmecophytic and two non-myrmecophytic Piper species revealed differences in their VOC emission profiles: Only in the myrmecophytic species were induced stress compounds found, such as various oxylipin RES or the sesquiterpene β-caryophyllene, which are typically emitted after plant damage for interplant signalling. Some of these compounds (e.g. hexanal, 1-hexanol) are known to induce alerting and alarm behaviours in several ant species. Our study provides evidence that the VOCs of the Piper host plant may signal stem damage and induce recruitment and alert behaviour of associated Pheidole ants. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach to solve feature subset selection problems using an Ant Colony Optimization (ACO) algorithm. ACO is one of the important naturally inspired intelligent techniques. It is based on the foraging behavior of real ants in nature. The proposed ACO is combined with a number of nearest neighbor classifiers. The resulting ACO algorithm is applied to classify credit risk using data belonging to 1,411 firms obtained from a leading Greek commercial bank. The objective is to classify subject firms into several groups representing different levels of credit risk. The results of the proposed algorithm are compared with those of others including SVM, CART, and with two other metaheuristic algorithms using tabu search and genetic algorithms, both of which use nearest neighbor classifiers in the classification phase. The results suggest that the proposed method is more accurate than others that have been tested in classifying credit risk. [ABSTRACT FROM AUTHOR]

Certain groups of organisms are capable of improving their collective performance with experience. In a recent study, we demonstrated that, over successive emigrations, colonies of the ant Temnothorax albipennis are able to improve their collective performance by reducing the time taken to complete an emigration (Langridge et al., Behav Ecol Sociobiol 56:523–529, 2004). In this paper, by recording the performance of individually marked workers during repeated emigrations, we were able to analyse some of the ways in which time gains are achieved. We found that: (1) those transporters that also transported in the preceding emigration began to transport earlier in the current emigration and, in the majority of emigrations, transported more items than those transporters that had not transported in the preceding emigration; (2) the time that elapsed before the first item was transported into the new nest reduced over successive emigrations, and this first item was, in the majority of emigrations, carried by a transporter that had also transported in the preceding emigration; (3) the number of adults that were transported reduced over successive emigrations. Our results strongly suggest that the behaviour of transporters that also transported in a preceding emigration may be modified as a result of their experience and that, consequently, their efforts in the next emigration make a major contribution to the improved performance of the colony as a whole. [ABSTRACT FROM AUTHOR]

The invasive African big-headed ant, Pheidole megacephala, is a dominant species in the many areas it has invaded. We examined whether one potential reason for its ecological success might be its predatory efficiency. We compared the density of termite nests in an area of Mexico invaded by P. megacephala with an adjacent area where P. megacephala is not present. We also compared the success of P. megacephala in preying on termites with that of 13 native ant species. We found that termite nest density was significantly lower in areas invaded by P. megacephala (0.33 vs. 1.05 nests per 30 m transect). In field trials, we established that P. megacephala workers were significantly more successful at capturing termite workers from termite nest fragments than even the most successful native ant species, Dorymyrmex pyramicus. For both P. megacephala and D. pyramicus, single scouts could trigger the mass recruitment of nestmates, but P. megacephala was able to recruit greater numbers of nestmates. Combined with their aggressiveness towards other ant species, their highly efficient predatory capacities help explain the ecological success of P. megacephala and demonstrate how it can be a major threat to invertebrate biodiversity in the areas it invades. [ABSTRACT FROM AUTHOR]

Ants exhibit collective behaviour in performing tasks that cannot be carried out by an individual ant. When ants are working, they must communicate with each other through a kind of chemical substance—pheromones. Ants look for food and lay the way back to their nest with pheromones, and the other ants can follow the pheromone to find the food efficiently. Using the analogy of foraging behaviour and pheromones, Marco Dorigo proposed the ant algorithm and applied it to solving the travelling salesman problem (TSP) and solving job-shop scheduling. In this paper, we simulate real ants with more aspects. Updating of pheromones is more likely to be the real situation in the natural world. Our algorithm shows a better performance than the original algorithm. [ABSTRACT FROM AUTHOR]

Insect social parasites are characterized by exploiting the hosts' social behaviour. Why exactly hosts direct their caring behaviour towards these parasites and their offspring remains largely unstudied. One hypothesis is that hosts do not perceive their social environment as altered and accept the parasitic colony as their own. We used the ant Leptothorax acervorum, host of the dulotic, obligate social parasite Harpagoxenus sublaevis, to shed light on molecular mechanisms underlying behavioural exploitation by contrasting tissue‐specific transcriptomes in young host workers. Host pupae were experimentally (re‐)introduced into fragments of their original, another conspecific, heterospecific or parasitic colony. Brain and antennal mRNA was extracted and sequenced from adult ants after they had lived in the experimental colony for at least 50 days after eclosion. The resulting transcriptomes of L. acervorum revealed that ants were indeed affected by their social environment. Host brain transcriptomes were altered by the presence of social parasites, suggesting that the parasitic environment influences brain activity, which may be linked to behavioural changes. Transcriptional activity in the antennae changed most with the presence of unrelated individuals, regardless of whether they were conspecifics or parasites. This suggests early priming of odour perception, which was further supported by sensory perception of odour as an enriched function of differentially expressed genes. Furthermore, gene expression in the antennae, but not in the brain corresponded to ant worker behaviour before sampling. Our study demonstrated that the exploitation of social behaviours by brood parasites correlates with transcriptomic alterations in the central and peripheral nervous systems. [ABSTRACT FROM AUTHOR]

Simple Summary: Alcoholism (addiction to ethanol, a common alcohol present in our beverages) is among the most important problems encountered in the domain of human mental health. The research devoted to behavioural effects of exposure to/consumption of ethanol is carried out largely with the help of animal models that include not only vertebrates such as rats and mice, but also insects, in particular fruit flies and honeybees. The effects of ethanol on ant behaviour remain, however, little known. In the present field study, we investigated the behaviour displayed by workers of the narrow-headed ant (Formica exsecta) in the vicinity of cotton pads soaked either in water or in water solutions of ethanol or acetic acid. Both ethanol and acetic acid induced significant modifications of ant behaviour, influencing various aspects of ant locomotion, exploratory behaviour, self-grooming behaviour, and aggressive social behaviour. We confirmed that acetic acid is aversive for the ants, but ethanol induces their interest. We also found out that field studies may discover more effects of experimental compounds than laboratory ones, as the tested animals may escape from aversive substances. Our present results also broadened the general knowledge about behavioural responses to ethanol and acetic acid encountered in animals. Ethanol addiction belongs to the most important problems encountered in the domain of human mental health. The research on the behavioural effects of exposure to/consumption of ethanol are investigated largely with the help of animal models that also include insects, mainly fruit flies and honeybees. The effects of ethanol on ant behaviour remain, however, little known. In the present field study, we investigated the behaviour of workers of the narrow-headed ant (Formica exsecta) displayed in the vicinity of cotton pads soaked in water or in water solutions of ethanol or acetic acid during 5 min tests (n = 30 tests in each group). Both ethanol and acetic acid induced significant modifications of ant locomotion, exploratory behaviour, self-grooming behaviour, and aggressive social behaviour. We confirmed that acetic acid is aversive for the ants, but ethanol enhances their exploratory behaviour. We also found out that field studies may document more types of responses to experimental compounds than laboratory ones, as the tested animals may also escape from aversive substances. Our findings documented a wide spectrum of behavioural effects of exposure to ethanol and acetic acid in a highly social animal species and broadened the general knowledge about behavioural responses to these compounds encountered in animals. [ABSTRACT FROM AUTHOR]

This article examines the semantic and syntactic properties of French deverbal adjectives ending in ¬-ant, and shows that a subpart of these forms, while behaving as adjectives with regards to agreement and predicative position, are episodic and imperfective, similarly to present participles, whose suffix is formally similar. We first observe the various readings of -ant adjectives, i.e. dispositional, potential and habitual (Fábregas, Antonio. 2016. Deconstructing the non-episodic readings of Spanish deverbal adjectives. Word Structure 9-1. 1–41; Fábregas, Antonio. 2020. Morphologically derived adjectives in Spanish. John Benjamins), and show that they parallel those of the corresponding verbs when they occur in generic sentences. We then show that some of these -ant adjectives refer to specific events and that the sentences in which they occur are semantically equivalent to those containing imperfective or progressive verbs forms, as shown by their positive reaction to the imperfective tests. Turning to the verbal bases of episodic -ant adjectives, we observe that they derive from a restricted number of atelic verbs, that surface without direct objects, have non-active subjects, and include a degree component in their lexical meaning. We finally provide a syntactic analysis of -ant adjectives, that relies on the idea that they contain both verbal and adjectival projections in their inner structure. We hypothesize that episodic adjectives are built by the means of a particular adjectival -ant marker, that maintains the imperfective value of the present participle marker. By contrast, other -ant adjectives are built by a homophonous adjectival suffix. [ABSTRACT FROM AUTHOR]

Animals construct and inhabit nests that can exhibit dramatic intra- and interspecific variation due to differences in behaviour, the biotic and abiotic environment, and evolutionary history. In ants, variation in nest architecture reflects both differences in ecology and in the collective behaviour of the colonies that live in the nests. Each component of the nest (such as depth, and the number, size and connectivity of chambers) reflects selective pressures for different functions, or structural constraints that are imposed by the environment or evolutionary history. To determine potential drivers of nest structure variation in subterranean nests, we performed a meta-analysis of measures of published ant nests to compare different structural elements within and across species. We complemented this survey with 42 nest casts of two closely related species. We quantified nest features that can potentially impact ant foraging behaviour and examined whether phylogeny or foraging strategy are better explanatory variables for the variation we observed. We found that foraging strategy better explained nest features than evolutionary history. Our work reveals the importance of ecology in shaping nest structure and provides an important foundation for future investigations into the selective pressures that have shaped ant nest architecture. This article is part of the theme issue 'The evolutionary ecology of nests: a cross-taxon approach'. [ABSTRACT FROM AUTHOR]

Nature-inspired metaheuristics of the swarm intelligence field are a powerful approach to solve electromagnetic optimization problems. Ant lion optimizer (ALO) is a nature-inspired stochastic metaheuristic that mimics the hunting behavior of ant lions using steps of random walk of ants, building traps, entrapment of ants in traps, catching preys, and re-building traps. To extend the classical single-objective ALO, this paper proposes four multiobjective ALO (MOALO) approaches using crowding distance, dominance concept for selecting the elite, and tournament selection mechanism with different schemes to select the leader. Numerical results from a multiobjective constrained brushless direct current (DC) motor design problem show that some MOALO approaches present promising performance in terms of Pareto-optimal solutions. [ABSTRACT FROM AUTHOR]

The article examines the antennal movements of ants that undergo an ontogenetic process. The repertoire of antennal movements of the callow worker, whether it is receiving or giving food, is mixed, combining the behavioral units of both the mature receiver and donor. This paper, thus, reports the results of a study of antennal activity in callow worker ants during liquid food transfers from mouth to mouth, and of the ontogenesis of this activity with respect to the early social experience.

Abstract. The paper presents a mathematical model to investigate the collective behaviour of an ant colony when memory of the ants interferes with the usual interaction between individuals. The approach is developed in the framework of a simple situation consisting in tandem recruitment in a population of conservative ants, but it is susceptible to be applied also to a wider range of problems. The principle of the method is inspired by the work of Leuthausser and Tarazona who developed the correspondence between a model for macromolecular time evolution and the equilibrium statistical mechanics of a higher-dimensional using system. [ABSTRACT FROM AUTHOR]

For spot-welding process, rational path planning of weld points can improve productivity for welding robot. In basic ant colony optimization, at the beginning of the iteration, the pheromone concentration is only related to the path length, but at this time, the path often contains a lot of redundant parts. Therefore, the pheromone in the initial iteration is almost difficult to reflect the advantages and disadvantages of the node, and it requires multiple iterations to slowly show the advantages and disadvantages of the path. For this shortcoming, a Monte Carlo-based improve ant colony optimization (MC-IACO) is proposed to solve the path planning of welding robots. The MC-IACO algorithm samples the path results generated in each generation and converts them into Monte Carlo indexes of the nodes. By substituting the Monte Carlo index of the feasible node into the sigmoid function, the probability that the corresponding node may constitute the optimal path, namely the Monte Carlo factor, is calculated to help ants make decisions. The new node transfer formula constructed with this factor can effectively improve the path finding efficiency of ants and the efficiency of the algorithm to complete the path planning task. The feedback adjustment factor is introduced to make the judgment of the advantages and disadvantages of feasible nodes also refer to the advantages and disadvantages of subsequent nodes. The simulation results show that compared with the basic ant colony optimization and other improved ant colony optimization, the MC-IACO algorithm in this paper improves significantly in solving the path planning problem of the welding robot, and its overall performance is better. [ABSTRACT FROM AUTHOR]

The complexity of industrial processes has grown exponentially, with high degrees of dependency, non-linearity, imprecision, among other aspects, which motivates the interest in developing distributed control systems for their management. In this sense, this work proposes a bio-inspired distributed control approach, where control actions emerge from the component interactions. The distributed control approach is based on the response threshold model to solve the control problem by imitating the behavior of ants. Particularly, our approach is inspired by the way as the ants carry out the division of labor in a colony. Thus, our control approach based on the threshold response model refers to the possibility of reacting to stimuli associated with the distributed control tasks. It has the ability to stabilize the process in the presence of abrupt/successive changes and various initial conditions, with a minimum effort of the actuators to achieve the objectives. Also, it has shown its versatility in different operational contexts with the same parameter tuning. The bio-inspired control approach is proved in a quadruple tank process, a complex system due to its multivariate nature. In this way, our paper introduces a new domain of application of the response threshold model in industrial processes. Several experiments were carried out in different contexts to evaluate its stability, robustness, etc., and compare it with other similar works. In general, the control performance metrics show satisfactory results, which reflects its ability to adapt to changes in the dynamics of the process, which encourages additional studies. • The response threshold model for the control of the quadruple tank process. • An emerging controller based on the response threshold model. • A distributed control approach for systems with high degree of dependency, non-linearity and imprecision. • The response threshold model based on the behavior of the ant colonies for control tasks. • Collective intelligence techniques for the definition of emerging controllers. [ABSTRACT FROM AUTHOR]

At the start of a journey home or to a foraging site, ants often stop, interrupting their forward movement, turn on the spot a number of times, and fixate in different directions. These scanning bouts are thought to provide visual information for choosing a path to travel. The temporal organization of such scanning bouts has implications about the neural organisation of navigational behaviour. We examined (1) the temporal distribution of the start of such scanning bouts and (2) the dynamics of saccadic body turns and fixations that compose a scanning bout in Australian desert ants, Melophorus bagoti, as they came out of a walled channel onto open field at the start of their homeward journey. Ants were caught when they neared their nest and displaced to different locations to start their journey home again. The observed parameters were mostly similar across familiar and unfamiliar locations. The turning angles of saccadic body turning to the right or left showed some stereotypy, with a peak just under 45°. The direction of such saccades appears to be determined by a slow oscillatory process as described in other insect species. In timing, however, both the distribution of inter-scanning-bout intervals and individual fixation durations showed exponential characteristics, the signature for a random-rate or Poisson process. Neurobiologically, therefore, there must be some process that switches behaviour (starting a scanning bout or ending a fixation) with equal probability at every moment in time. We discuss how chance events in the ant brain that occasionally reach a threshold for triggering such behaviours can generate the results. [ABSTRACT FROM AUTHOR]

Wood ants are excellent navigators, using a combination of innate and learnt navigational strategies to travel between their nest and feeding sites. Visual navigation in ants has been studied extensively, however, we have little direct evidence for the underlying neural mechanisms. Here, we perform lateralized mechanical lesions in the central complex (CX) of wood ants, a midline structure known to allow an insect to keep track of the direction of sensory cues relative to its own orientation and to control movement. We lesioned two groups of ants and observed their behaviour in an arena with a large visual landmark present. The first group of ants were naïve and when intact such ants show a clear innate attraction to the conspicuous landmark. The second group of ants were trained to aim to a food location to the side of the landmark. The general heading of naïve ants towards a visual cue was not altered by the lesions, but the heading of ants trained to a landmark adjacent food position was affected. Thus, CX lesions had a specific impact on learnt visual guidance. We also observed that lateralised lesions altered the fine details of turning with lesioned ants spending less time turning to the side ipsilateral of the lesion. The results confirm the role of the CX in turn control and highlight its important role in the implementation of learnt behaviours that rely on information from other brain regions. [ABSTRACT FROM AUTHOR]

Some Ophiocordyceps species infecting ants are able to manipulate the host behavior. The hosts are manipulated in order to move to location that are advantageous for fungal spore transmission. Ophiocordyceps species that are able to manipulate the ant's behavior are called "zombie-ant fungi". They are widespread within tropical forests worldwide, with relatively few reports from subtropical monsoon evergreen broad-leaf forest. Zombie-ant fungi have been described and reported in different countries worldwide. However, there were a few reports from China. This study proposed six new species of zombie-ant fungi from China based on multi-gene (SSU, LSU, TEF, RPB1 and RPB2) phylogenetic analyses and morphological characteristics. Six novel species of Ophiocordyceps from China were identified as the Ophiocordyceps unilateralis core clade, forming a separate lineage with other species. Six novel species of Ophiocordyceps with hirsutella-like asexual morphs exclusively infecting ants were presented herein, namely, Ophiocordyceps acroasca, Ophiocordyceps bifertilis, Ophiocordyceps subtiliphialida, Ophiocordyceps basiasca, Ophiocordyceps nuozhaduensis and Ophiocordyceps contiispora. Descriptions and illustrations for six taxon were provided. Five of these species were collected from the subtropical monsoon evergreen broad-leaf forest, and one was collected from the rainforest and subtropical monsoon evergreen broad-leaf forest. This work proposes that the same host of Camponotus can be infected by multiple ant pathogenic fungi, while multiple ants of Polyrhachis can be infected by the same pathogenic fungi at the same time. This study contributes towards a better understanding of the evolutionary relationship between hosts and fungi, and provides novel insights into the morphology, distribution, parasitism, and ecology of Ophiocordyceps unilateralis sensu lato. We have provided a method for obtaining living cultures of Ophiocordyceps unilateralis complex species and their asexual morphs based on the living cultures, which is of significant value for further studies of Ophiocordyceps unilateralis complex species in the future. [ABSTRACT FROM AUTHOR]