Ant Species Research Articles

Harmony under threat: does resource-mediated stress affect the (caste-based) social network of leaf-cutting ant colonies?

Managing pest species of eusocial insects, such as leaf-cutting ants, poses significant challenges. Controlling them requires understanding of how toxic plant substrates and ant baits are recognized by foragers, transported to the nest, shared among workers and managed by gardeners cultivating the symbiont fungus garden. Despite this, little is known about how unsuitable resources might impact social interactions within ant colonies. This study aims to investigate whether the provision of a suitable substrate (copperleaf) and a toxic substrate (nasturtium leaves) affects the social network dynamics within colonies of two leaf-cutting ant species: Acromyrmex molestans and Acromyrmex subterraneus. The interactions between castes were recorded and subjected to social network analyses. Initial foraging duration increased for A. subterraneus provided with copperleaf, although no difference was observed for the other species and resource combinations. The social network structure was similar for both species when copperleaf leaves were provided as a substrate. However, notable alterations occurred with nasturtium leaf provision, leading to higher integration of gardeners in interactions and noticeable changes in the generalist worker network centrality, particularly in A. subterraneus. The observed changes in social interactions, particularly in A. subterraneus, suggest that increasing gardener interactions with other castes expedites the movement of the substrate within the colony. This maximizes the potential toxic effect on the colony. © 2024 Society of Chemical Industry.

Discovering Native Ant Species with the Potential to Suppress Red Imported Fire Ants

Native ants have long been considered for their potential to suppress the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), a highly invasive and destructive species. However, the knowledge in this field is limited to behavioral observations of a few related native ants. In this study, by setting up a series of ant combinations of three native ants, i.e., Monomorium chinense Santschi, the robust crazy ant Nylanderia bourbonica Forel, and Iridomyrmex anceps Roger, with S. invicta, we observed the aggression levels and mortality rates. Using baited vials, we also investigated the abundance of native ants in four types of habitats in Eastern China that are preferred by S. invicta (woodland, green belts on roadsides, grassland, and farmland), as well as their seasonal abundance when co-existing with S. invicta and their spatial distribution before and after control of S. invicta. We found that M. chinense and N. bourbonica show a degree of aggression towards S. invicta and can kill substantial proportions of S. invicta under laboratory conditions, but I. anceps does not. Both M. chinense and N. bourbonica can occur in each type of habitat investigated and are more abundant in green belts (particularly lawns with turf) and grasslands relative to other habitats. In grasslands with S. invicta, M. chinense maintained a low density before early July; however, its abundance increased thereafter and reached a peak in September. N. bourbonica also had a low density early in the season and increased steadily from April. Its abundance began to decrease substantially from November. In grasslands invaded by S. invicta, both M. chinense and N. bourbonica were restricted to sites close to the margins before S. invicta was controlled; however, they spread to a larger range within a few weeks after control of S. invicta. In conclusion, M. chinense and N. bourbonica have the potential to suppress S. invicta invasion in habitats that are abundant with these two native ants.

Chromosome Mapping of Ribosomal DNA Clusters in Four Leaf-cutting Ant Species of the Genus Acromyrmex, with Description of a Triploid Individual in A. laticeps

The increase of cytogenetic data in the leaf-cutting genus Acromyrmex has shown interesting contributions to the evolutionary and taxonomic approaches, including the creation of a new genus and the description of chromosomal patterns allowing comparative studies within Acromyrmex as well as between this genus and other similar taxa. The conserved chromosome number in Acromyrmex is a notable feature, with some distinguishable chromosomes among the species. In this study, we describe the diploid karyotype of Acromyrmex laticeps in addition to an individual with all the metaphases triploids, suggesting a triploid individual. To the best of our knowledge, this is the first report of polyploidy in a fungus-growing ant. Furthermore, we mapped 18S ribosomal DNA on the chromosomes of A. laticeps and three other Acromyrmex species. Among them, three species showed the ribosomal DNA cluster pattern observed in other previously studied members of this genus, with a terminal location in the largest subtelocentric pair. Meanwhile, Acromyrmex balzani had these ribosomal DNA clusters in its entire short arm. The role of triploidy in ant evolution has also been discussed. The increase in chromosomal data of leaf-cutting ants may provide significant insights into the evolution of this peculiar ant group.

Stinging Ant Anaphylaxis: Advances in Diagnosis and Treatment

Stinging ants represent a wide range of over 200 different species across the world, of which Solenopsis, Myrmecia, Pogonomyrmex, and Brachyponera genera, account for a substantial economic and healthcare burden. S. invicta (red imported fire ant; IFA) and M. pilosula (jack jumper ant; JJA) are 2 species of high clinical importance, known to cause anaphylaxis in humans, with numerous reported fatalities. Diagnostic testing should be performed in patients with a history of a systemic reaction with skin testing and/or in vitro specific-IgE testing. In vitro testing is commercially available for IFA through whole-body extract (WBE) specific-IgE and JJA venom specific-IgE, but not widely available for other stinging ant species. Commercial venom component testing for IFA and JJA is currently not available. Patients with a clinical history and positive specific-IgE testing, should undergo treatment with specific immunotherapy, which is currently available for IFA and JJA. Build-up may be performed using conventional, semi-rush, rush, or ultra-rush schedules with similar risk profiles for IFA. Optimal duration for WBE immunotherapy for IFA and specific JJA venom immunotherapy is not well-studied, but generally recommended for at least 3-5 years. Sting challenges are used in research settings, primarily to assess treatment efficacy of immunotherapy.

Nasturtium leaf compounds, diphenyl disulfide and lyral, against Atta sexdens (Hymenoptera: Formicidae)and their symbiotic fungi.

Social insect pests, particularly leaf-cutting ants, present a considerable challenge in terms of control. Leaf-cutting ants are significant agricultural, forestry, and pasture pests, and understanding their behavior and defense mechanisms is essential for managing their colonies effectively. While toxic ant baits are a primary control method, the limited availability of effective insecticides and concerns over their hazardous nature has spurred the search for alternative solutions, particularly natural compounds, which aligns with the goals of forest certification groups. In the light of previous evidence demonstrating the efficacy of nasturtium leaves (Tropaeolum majus L. (Brassicales: Tropaeolaceae)) in suppressing leaf-cutting ant colonies, this study investigates 2 active components of nasturtium leaf extracts: diphenyl disulfide and lyral. We tested their impact on Atta sexdens (L.) (Hymenoptera: Formicidae), the most prevalent leaf-cutter ant species in Brazil, and their symbiotic fungus, Leucoagaricus gongylophorus (Möller) Singer (Agaricales: Agaricaceae). We conducted experiments with increasing concentrations of diphenyl disulfide and lyral, assessing their effects on the symbiotic fungus and on forager workers and gardeners of A. sexdens colonies. Our findings revealed no fungicidal activity, and ant mortality was minimal in both topical and ingestion bioassays with the exception of gardeners topically exposed to diphenyl sulfide. Furthermore, the compounds did not affect leaf ingestion, but diphenyl disulfide did increase interactions among foragers. These results suggest that neither diphenyl disulfide nor lyral are the primary contributors to the suppression of leaf-cutting ant colonies by nasturtium leaves. However, they may enhance the formicidal activity of other compounds present in nasturtium leaves.

Prve najdbe mirmekofilnega pajka <i>Thyreosthenius biovatus</i> (O. Pickard-Cambridge, 1875) za Slovenijo in nove slovenske najdbe mirmekofilnega pajka <i>Mastigusa arietina</i> (Thorell, 1871)

Ants from the Formica rufa group, also known as red wood ants, build large mound nests and play an important role in their environment, especially in forests. Their nests harbour a species rich and abundant myrmecophilous fauna, including a few European spider species. Myrmecophilous spiders in 40 nests of red wood ants from 25 sites were searched for in Slovenia. In each mound nest, four to five litres of material were collected, which were placed in a sifter, with the sifted material examined for the presence of spiders. Two myrmecophilous spider species were found in the nests: Thyreosthenius biovatus (fam. Linyphiidae), representing first records for Slovenia, and Mastigusa arietina (fam. Cybaeidae), previously known from several sites in western Slovenia, but never purposefully searched for in ant nests. The first spider species was found in half of the examined nests, belonging to all sampled species of red wood ants, most of them to F. aquilonia, and M. arietina was detected in 37.5% of the examined nests, belonging to F. aquilonia and F. lugubris. The two spider species are presumably not rare in Slovenia, especially in the areas with a high number of red wood ant nests.

Colour pattern diversity and evolution in Oriental velvet ants (Hymenoptera: Aculeata: Mutillidae)

Abstract The Mutillidae (Hymenoptera: Aculeata) are a family of solitary ectoparasitoid wasps, famous for their sting and conspicuous coloration. The occurrence of Müllerian mimicry complexes has been demonstrated in both Africa and North America. Müllerian mimicry is the resemblance between several harmful species, advertising their defence to would-be predators by sharing a conspicuous colour pattern. Various colour patterns are known to occur in Oriental (Asian) velvet ants, but potential Müllerian mimicry complexes have not yet been inferred. We analysed the coloration of the females of 283 Oriental velvet ant species (52 genera), characterized by 12 phenotypic traits, and we identified shared colour patterns. Morphological differences between groups were tested using non-metric multidimensional scaling and permutational multivariate analysis of variance. We also inferred the geographical range of these colour patterns, and we investigated whether the shared patterns are the result of convergent evolution or common ancestry. We identified six distinct shared colour patterns, of which four can be associated with Müllerian mimicry. We also studied the position and shape of metasomal markings, and we found no association with mimicry rings. Our results improve the understanding of colour evolution in Oriental velvet ants and extend the previously described Müllerian mimicry complex to the south Asiatic landmass.

Nest Biota and Composition of Household Ants in Lafia Local Government Area, Nasarawa State

Household ants are an important group of insect pests because of their close association with man. However, there is less data on their role in the mechanical spread of diseases in the study area. Therefore, this study investigated ant species and the soil microbes in their nest in Lafia Local Government Area of Nasarawa State, Nigeria in August, 2023. A cross-sectional study was carried out in 60 households across three developmental areas using hand-picking methods for ants’ collection as well as soil samples collection from available nests which were transferred in sample containers and transported to the laboratory for ants’ identification, parasitological analysis and culture. 3,015 ants belonging to five subfamilies, 15 genera and 17 species were collected. The most dominant ant was Brachyponera sennaarensis (21.43%), while Solenopsis spp. was least dominant (0.23%). Of the selected ants screened, none had ecto and endo-parasites. Although three (3) species of soil transmitted helminths were found in the soil analyzed using sedimentation method and the modified Baermann’s funnel technique in which Strongyloides starcoralis 16(26.67%) was more prevalent. Ants were also contaminated with (13) species of bacteria of which Escherichia coli was the most frequent (22.63%) pathogenic bacteria. Candida spp. was also recorded in the study. Consequently, Households in the study sites show increasingly high number of ants due to their efficient feeding and nesting activities; this may support the mechanical spread of helminths and soil pathogenic microbes, therefore proper sanitation as well as integrated control measures against ant infestation should be given due consideration.

Common ant species dominate morphospace: unraveling the morphological diversity in the Brazilian Amazon Basin

Rare plant and vertebrate species have been documented to contribute disproportionately to the total morphological structure of species assemblages. These species often possess morphologically extreme traits and occupy the boundaries of morphological space. As rare species are at greater risk of extinction than more widely distributed species, human‐induced disturbances can strongly affect ecosystem functions related to assemblage morphology. Here, we assess to what extent the distributions of ant morphological traits are supported by morphologically extreme species and how they are distributed among habitats in a global biodiversity hotspot, the Brazilian Amazon. We used a morphological database comprising 15 continuous morphological traits and 977 expert‐validated ant species distributed across the Brazilian Amazon. We produced species range estimates using species distribution models or alpha hulls (when few records were available). Next, we conducted a principal components analysis to combine traits into a space with reduced dimensionality (morphospace). Then, we identified morphologically extreme species in this space and quantified their contributions to morphological diversity across different habitat types in the Brazilian Amazon Basin. We identified 114 morphologically extreme ant species across the Amazon ant morphospace. These species also accounted for a large percentage of morphospace filling, exceeding 99% representation in the most disturbed habitats in the Amazon. Our results suggest that a few morphologically extreme species capture most of the variation in ant morphology and, therefore, the spectrum of ecosystem functions performed by ants in the Brazilian Amazon Basin. Further, unlike in many other groups, these extreme morphologies were represented by the set of most common species. These results suggest greater functional redundancy and resilience in Brazilian Amazon ants, but more broadly, they contribute to our understanding of ecological processes that sustain ecosystem functions.

Common ant species dominate morphospace: unraveling the morphological diversity in the Brazilian Amazon Basin

Common ant species dominate morphospace: unraveling the morphological diversity in the Brazilian Amazon Basin

An assemblage-level comparison of genetic diversity and population genetic structure between island and mainland ant populations.

Island biotas provide unparalleled opportunities to examine evolutionary processes. Founder effects and bottlenecks, for example, typically decrease genetic diversity in island populations, while selection for reduced dispersal can increase population structure. Given that support for these generalities mostly comes from single-species analyses, assemblage-level comparisons are needed to clarify how (i) colonization affects the gene pools of interacting insular organisms, and (ii) patterns of genetic differentiation vary within assemblages of organisms. Here, we use genome-wide sequence data from ultraconserved elements (UCEs) to compare genetic diversity and population structure of mainland and island populations of nine ant species in coastal southern California. As expected, island populations (from Santa Cruz Island) had lower expected heterozygosity and Watterson's theta compared to mainland populations (from the Lompoc Valley). Island populations, however, exhibited smaller genetic distances among samples, indicating less population subdivision. Within the focal assemblage, pairwise Fst values revealed pronounced interspecific variation in mainland-island differentiation, which increases with gyne body size. Our results reveal population differences across an assemblage of interacting species, and illuminate general patterns of insularization in ants. Compared to single-species studies, our analysis of nine conspecific population pairs from the same island-mainland system offers a powerful approach to studying fundamental evolutionary processes.

Confirmed presence of the enigmatic ant Aphaenogaster gemella (Hymenoptera: Formicidae) in Iberia

BackgroundWhile the Iberian Peninsula has been relatively well-studied from a myrmecological standpoint, the true presence of certain ant species has remained obscure for decades. In this context, the case of A. gemella (Roger, 1862) stands out as one of the most intriguing examples. Initially described from the Balearic Islands, this conspicuous species seemingly vanished from the archipelago by the 1980s, confining its current distribution to the Maghreb region. However, lingering doubt has persisted regarding its potential presence in Iberia, based on some old bibliographic records from Spain and Portugal.ResultsThis study confirms the first known established population of A. gemella in the Iberian Peninsula (Tarifa, Southern Iberia). Two colonies were detected in an urban grass patch within the city center. The validity of other Iberian records regarding the species and its status as an exotic species are also discussed.ConclusionsThe presence of A. gemella in Southern Iberia highlights the need for targeted sampling efforts to delineate its actual range and distinguish it from morphologically similar species in the region.

Ant Colony Optimization for solving Directed Chinese Postman Problem

AbstractThe Chinese Postman Problem (CPP) is a well-known optimization problem involving determining the shortest route, modeling the system as an undirected graph, for delivering mail, ensuring all roads are traversed while returning to the post office. The Directed Chinese Postman Problem (DCPP) extends the Chinese Postman Problem (CPP), where the underlying graph representing the system incorporates exclusively directed edges. Similarly to CPP, this problem has plenty of applications in route optimization, interactive system analysis, and circuit design problems. However, due to the added constraint (directionality of edges), DCPP results are more challenging to solve. Although methods to solve it in literature are proposed, typically by using minimum-cost-flow algorithms, the meta-heuristics approaches proposed to deal with it are very limited. In this paper, we propose an innovative meta-heuristic approach to solve DCPP by using an ant colony optimization (ACO) algorithm, i.e., an algorithm that simulates in a simplified way the behavior of some species of ants to solve optimization problems. The efficiency of our ant colony optimization for solving the Directed Chinese Postman Problem (ACO-DCPP) is measured by comparing the ACO outcomes with the results obtained by a recursive algorithm that explores all the possible solutions. Results show that ACO-DCPP is stable and gets the global optimum frequently by using an extremely limited number of solutions explored.

A soluble model for synchronized rhythmic activity in ant colonies

Synchronization is one of the most striking instances of collective behavior, occurring in many natural phenomena. For example, in some ant species, ants are inactive within the nest most of the time, but their bursts of activity are highly synchronized and involve the entire nest population. Here we revisit a simulation model that generates this synchronized rhythmic activity through autocatalytic behavior, i.e., active ants can activate inactive ants, followed by a period of rest. We derive a set of delay differential equations that provide an accurate description of the simulations for large ant colonies. Analysis of the fixed-point solutions, complemented by numerical integration of the equations, indicates the existence of stable limit-cycle solutions when the rest period is greater than a threshold and the event of spontaneous activation of inactive ants is very unlikely, so that most of the arousal of ants is done by active ants. Furthermore, we argue that the persistent oscillations observed in the simulations for colonies of finite size are due to resonant amplification of demographic noise.

Ant social network structure is highly conserved across species.

The ecological success of social insects makes their colony organization fascinating to scientists studying collective systems. In recent years, the combination of automated behavioural tracking and social network analysis has deepened our understanding of many aspects of colony organization. However, because studies have typically worked with single species, we know little about interspecific variation in network structure. Here, we conduct a comparative network analysis across five ant species from five subfamilies, separated by more than 100 Myr of evolution. We find that social network structure is highly conserved across subfamilies. All species studied form modular networks, with two social communities, a similar distribution of individuals between the two communities, and equivalent mapping of task performance onto the communities. Against this backdrop of organizational similarity, queens of the different species occupied qualitatively distinct network positions. The deep conservation of the two community structure implies that the most fundamental behavioural division of labour in social insects is between workers that stay in the nest to rear brood, and those that leave the nest to forage. This division has parallels across the animal kingdom in systems of biparental care and probably represents the most readily evolvable form of behavioural division of labour.

Physical chromosomal mapping of major ribosomal genes in 15 ant species with a review of hypotheses regarding evolution of the number and position of NORs in ants.

Recently, hypotheses regarding the evolutionary patterns of ribosomal genes in ant chromosomes have been under discussion. One of these hypotheses proposes a relationship between chromosomal location and the number of rDNA sites, suggesting that terminal locations facilitate the dispersion of rDNA clusters through ectopic recombination during meiosis, while intrachromosomal locations restrict them to a single chromosome pair. Another hypothesis suggests that the multiplication of rDNA sites could be associated with an increase in the chromosome number in Hymenoptera due to chromosomal fissions. In this study, we physically mapped rDNA sites in 15 new ant species and also reviewed data on rDNA available since the revision by Teixeira et al. (2021a). Our objectives were to investigate whether the new data confirm the relationship between chromosomal location and the number of rDNA sites, and whether the increase in the chromosome number is significant in the dispersion of rDNA clusters in ant karyotypes. Combining our new data with all information on ant cytogenetics published after 2021, 40 new species and nine new genera were assembled. Most species exhibited intrachromosomal rDNA sites on a single chromosome pair, while three species showed these genes in terminal regions of multiple chromosome pairs. On one hand, the hypothesis that the chromosomal location of rDNA clusters may facilitate the dispersion of rDNA sites in the ant genome, as previously discussed, was strengthened, but, on the other hand, the hypothesis of chromosomal fission as the main mechanism for dispersion of ribosomal genes in ants is likely to be refuted. Furthermore, in certain genera, the location of rDNA sites remained similar among the species studied, whereas in others, the distribution of these genes showed significant variation between species, suggesting a more dynamic chromosomal evolution.

Macroecological patterns of functional and phylogenetic diversity vary between ground and arboreal assemblages in Neotropical savanna ants

Macroscale environmental gradients can have contrasting effects on organisms that occupy different vertical niches, but we have little understanding of how this might result in different macroscale diversity patterns in ground and arboreal communities. We also have little understanding of how different dimensions of diversity, such as functional and phylogenetic diversity, vary along macroscale environmental gradients. Here we examine latitudinal and elevational patterns of different dimensions of diversity for both ground and arboreal assemblages in Neotropical savanna ants. The study was based on ant species occurring at 32 sites covering a 22° range of latitude and > 1000 m range in elevation in Brazil. Functional and phylogenetic richness were positively correlated with species richness, all increasing with latitude. However, the greater phylogenetic richness on the ground than in trees did not simply reflect differences in species richness. The mean functional and phylogenetic divergence among species was also greater on the ground than in trees, indicating a stronger role of competition. Both mean functional and phylogenetic divergence showed negative correlations with elevation in trees but not on the ground. In trees, the standardized effect size (taking into account differences in species richness) of mean functional divergence was negatively related to elevation and mean phylogenetic divergence was negatively related to both latitude and elevation. These findings suggest that as temperature decreases the relative importance of environmental filtering in arboreal but not ground communities increases (and that of competition and niche partitioning decreases). Overall, we show that the macroecological patterns of ant species richness that have previously been reported for Brazilian savannas do not adequately represent other dimensions of diversity, and that the representativeness differs between vertical strata. Macroecological patterns of functional and phylogenetic divergence indicate that the relative importance of competition and environmental filtering also differs between vertical strata.

The ManhattAnt: identification, distribution, and colony structure of a new pest in New York City, Lasius emarginatus

AbstractAn unidentified ant species was discovered in the heart of New York City in 2011, which garnered national headlines and created the memorable nickname “ManhattAnt.” New York City is one of the oldest and largest cities in North America and has been the site of introduction for some of North America’s most damaging invasive pests. Nevertheless, there has been little follow up research on the ManhattAnt since its discovery, and it has yet to be formally identified. Here we use genetic and morphological approaches to confirm the identity of the ManhattAnt and characterize its introduced range and colony structure. Results from genetic analyses placed the ManhattAnt within the Lasius emarginatus species complex, and morphological comparisons ruled out closely related species to identify the ManhattAnt as the European ant L. emarginatus with 93–99% certainty depending on the nest sample. Since its initial discovery in the region, the ManhattAnt has become one of the most common ants in New York City and has spread at a rate of 2 km/yr into New Jersey and onto Long Island. Based on the climate it inhabits within its native range, L. emarginatus could expand to cover much of the eastern United states from Massachusetts to Georgia. Although many successful invasive ants display supercoloniality with little aggression between neighboring nests, we found no evidence that L. emarginatus colonies in New York City are supercolonial. Continued monitoring of L. emarginatus is warranted, as it has been increasingly reported as an indoor pest and is known to form mutualisms with honeydew producing pests of street trees.

The Diversity of Ants (Formicidae) in Gunung Palung National Park as a Biology Learning Resource

Gunung Palung National Park (GPNP) has a diversity of ant, but the information as a source of learning is still lacking. This study aims to determine the diversity of ant species in the TNGP area and its potential as a source of learning. Research using descriptive qualitative method. Sampling used a pitfall trap placed on a line transect that passes through an alluvial soil forest. Collecting data on potential learning resources using the results of a questionnaire. The results showed that there were 90 individuals from 9 ant species specifically Dinomyrmex gigas, Polyrhachis bihamata, Rhytidoponera araneoides, Dolichoderus thoracicus, Axinidris Acholli, Hagensia havilandi, Myrmicaria brunnea, Anonychomyrma myrmex, Notostigma carazzii. The diversity of species of ants has the potential as a source of learning with indicators of clarity of potential (85%), ease of access (58.33%), security (91.66%), time efficiency (75%), cost (91.66%), suitability with learning objectives (100%), clarity of material objectives (100%), and clarity of information disclosed (100%). This research shows that information about ant diversity is very suitable as a source of learning biology, especially in the subjects of biology, biodiversity, and the classification of living things.

Nest excavators’ learning walks in the Australian desert ant Melophorus bagoti

The Australian red honey ant, Melophorus bagoti, stands out as the most thermophilic ant in Australia, engaging in all outdoor activities during the hottest periods of the day during summer months. This species of desert ants often navigates by means of path integration and learning landmark cues around the nest. In our study, we observed the outdoor activities of M. bagoti workers engaged in nest excavation, the maintenance of the nest structure, primarily by taking excess sand out of the nest. Before undertaking nest excavation, the ants conducted a single exploratory walk. Following their initial learning expedition, these ants then engaged in nest excavation activities. Consistent with previous findings on pre-foraging learning walks, after just one learning walk, the desert ants in our study demonstrated the ability to return home from locations 2 m away from the nest, although not from locations 4 m away. These findings indicate that even for activities like dumping excavated sand within a range of 5–10 cm outside the nest, these ants learn and utilize the visual landmark panorama around the nest.