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The connection between plant species and nest site preference for the Asian weaver ant Oecophylla smaragdina remains poorly understood despite their common occurrence in the urban areas of tropical regions. We predicted that plant species with specific leaf characteristics influence the nesting preference of Asian weaver ants, given that plant foliage is the main component of their nest structure. We studied the leaf characteristics of the tree species in which their nests were detected, including leaf shape, leaf apex shape, and leaf arrangement. Of the 206 total trees among the 20 tree species sampled, 185 trees from 18 tree species had at least one nest. Trees of the genus Lagerstroemia had the highest median nest abundance, whereas all Roystonea regia and Caryota no trees, and some Samanea saman trees, were not occupied by O. smaragdina. For the trees found to have O. smaragdina nests, the nest abundance in each tree ranged between 1 and 16 nests, with the majority having fewer than 10 nests per tree (4.38 ± 4.45). Based on nest abundance, the oblong and elliptic leaf shapes (LS), the cuspidate leaf apex shape (LX), and the opposite leaf arrangement (LR) were the most used for nest construction, consisting of more than 50% of the total in each respective category. A Kruskal-Wallis test revealed that O. smaragdina nest site preference is influenced by LX and LR but not by LS. Additionally, O. smaragdina nest abundance was negatively correlated to leaf surface ratio but insignificant for leaf surface area. These preferred qualitative and quantitative leaf characteristics determine the species of plants used as nesting sites to facilitate nest-building efficiency and the establishment of Asian weaver ant colonies. [ABSTRACT FROM AUTHOR]

Ant assemblages have been used as bioindicators of biodiversity response to different types of anthropogenic disturbances. However, usual diversity metrics (e.g., ant species richness and composition) sometimes seem limited in showing an overall panorama of human impacts. Thus, we checked habitat-use guilds of ants as a complementary predictable parameter, based on the ant fauna reported in thirteen forest fragments and pastures in the southwestern Brazilian Amazon. Specifically, we hypothesized that forest specialist, open-habitat specialist, and generalist ants would have distinct responses to forest-pasture shifting. We expected that forest-pasture shifting would cause a decrease in species richness of forest specialists and an increase in open-habitat specialists, while the generalists would have few changes in their richness because they can live in both habitats. As expected, the species richness of forest specialist ants decreased, and open-habitat ants increased with forest-pasture shifting, while generalists had little change. This indicates that human-induced open habitats (e.g., pastures) are essentially comprised of generalist ants and open-habitat ant specialists, which replace forest specialists. Additionally, considering the plasticity of generalist ants, they can be considered as primary elements of ant assemblages. Therefore, a future step is to quantify the limit of forest-cover clearing in human-induced land uses, which might ensure a higher species richness of forest-specialist ants than other habitat-use guilds. Implications for insect conservation: Habitat-use ant guilds (forest specialists, open-habitat specialists, and generalists) have been used as a complementary parameter on bioindication. Here, we provided a standard protocol to classify the ant fauna in these habitat-use guilds, which allows for objective, reproducible and broad use in monitoring programs that consider ant assemblages as bioindicators. [ABSTRACT FROM AUTHOR]

This study examined how chronic anthropogenic disturbance impacts the spatiotemporal dynamics of ant foraging activity and the role played by behavioral traits. Ten plots (0.1 ha) along a gradient of chronic disturbance intensity were sampled in Catimbau National Park (Caatinga vegetation, Brazil). Vegetative structure, ground surface temperature, and ant communities in shaded and sun-exposed microhabitats were characterized during the day and at night. Each ant species' degree of nocturnality and shaded microhabitat use were determined. Along the disturbance gradient, the frequency of sun-exposed microhabitats increased, as did the daytime ground surface temperatures; also, community composition, but not ant abundance or species richness, changed. Independent of disturbance intensity, community composition differed between day and night, and ant abundance and species richness were higher during the day. Interestingly, most species did not display strictly diurnal habits, nor did they avoid foraging in sun-exposed habitats. However, species common in more disturbed areas were more diurnal and used sun-exposed microhabitats more than species common in less disturbed areas. Many species displayed marked behavioral plasticity that was unrelated to disturbance intensity. Disturbance intensity did influence shaded microhabitat use but not the degree of nocturnality. We conclude that Caatinga ants are already morphologically, behaviorally and physiologically adapted to harsh environmental conditions; that species with different behavioral traits replace each other along the disturbance gradient; and that more plastic species can persist by shifting their microhabitat use. [ABSTRACT FROM AUTHOR]

With urbanisation increasing globally, conservation ecologists need to characterise the functioning of ecosystems embedded in urban landscapes. Ubiquitous and hyperdiverse, ants are an ideal model taxon for this purpose. Here we compared the diversity, richness, and abundance of ants in a forest fragment and a green urban area within the City of São Paulo, characterising relationships among ant species. We found higher species abundance and richness in the urban area, whereas diversity was greater in the secondary forest fragment. Transect sampling revealed higher heterogeneity in the more urban area, with a number of species not found in the secondary forest. Bait sampling suggested that, in the urban area, the dominance of one or a few species was stronger than in the secondary forest, possibly because the dominant species outnumbered other species at resources and behaved aggressively. We found that a limited number of species dominated in both the forest and the urban area. Although this study only relies on a limited sample size taken in relatively narrow geographic and climatic conditions, it suggests that ant community traits in urban environments vary depending on human-related disturbance. [ABSTRACT FROM AUTHOR]

Mutually beneficial associations are widespread in ecological networks. They are typically assembled as multispecies guilds of symbionts that compete for one or more host species. The ant Lasius flavus engages in an intriguing and obligate mutualistic association with a community of aphids that are cultivated on plant roots in its nests. The ant displays a repertoire of amicable behaviors toward the aphids, including their transport. I examined whether L. flavus preferentially carried some of the root aphids. Using a no-choice and a choice experiment, I comparatively analyzed the transport rate of 5 obligate and one loosely associated species back to the ant nest and used the transport rate of the ant larvae as a reference. All associated root aphids were carried back to the nest, but in a clear preferential hierarchy. Geoica utricularia, Forda Formicaria , and Trama rara were rapidly transported, but slower than the own larvae. Tetraneura ulmi and Geoica setulosa were collected at a moderate rate and the loosely associated Aploneura lentisci was slowly retrieved. In contrast, different species of unassociated aphids were not transported and even provoked aggressive behavior in L. flavus. This study revealed that co-occurring symbionts may induce different degrees of host attraction, which ultimately may affect the coexistence and assembly of ant-symbiont communities. [ABSTRACT FROM AUTHOR]

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To understand species' responses to climate change, we must better comprehend the factors shaping physiological critical thermal limits. One factor of potential importance is nutrient availability. Carbohydrates are an energy source that can directly affect an organism's physiological state. Ants are among the most omnipresent and ecologically relevant animal groups on Earth, and many ant species consume carbohydrate‐based diets. Additionally, as ectotherms, ants are highly vulnerable to the effects of climate change. Here, we examined the relationship between foraging temperature, carbohydrate availability, and critical thermal maximum (CTmax) in ants (Hymenoptera: Formicidae). First, we conducted a laboratory experiment using 3–4 colonies of two species that forage at high temperatures (Camponotus blandus Smith and Dorymyrmex thoracicus Gallardo) and two species that forage at lower temperatures (Nylanderia fulva Mayr and Dolichoderus quadridenticulatus Roger). Each colony was divided into two experimental subcolonies, which were given diets containing different carbohydrate concentrations (5 vs. 20% sucrose solutions). We then measured CTmax. We also collected ants belonging to these species in the field and measured their CTmax. We found that CTmax was highest for the two species that forage at higher temperatures. For C. blandus and D. thoracicus, workers given 20% sucrose had higher CTmax than workers given 5% sucrose. No diet‐mediated differences in CTmax were seen for N. fulva and D. quadridenticulatus workers. Additionally, the experimental ants in both treatment groups had higher CTmax than their field‐collected conspecifics, except in the case of C. blandus. If carbohydrate‐rich diets can boost heat tolerance in some species, it is possible that changes in resource availability could determine how climate change affects ants, especially species with carbohydrate‐based diets. Furthermore, these impacts could ripple across the entire trophic network. [ABSTRACT FROM AUTHOR]

Itaipu Hydroelectric Power Plant initiated a large reforestation programme after the expropriation of the areas destined for the formation of the reservoir. This study aimed to evaluate the effectiveness of forest restoration of the Seasonal Semideciduous Forest in the Upper Paraná Atlantic Forest ecoregion, Brazil, using epigaeic ant assemblages as bioindicators, by comparing ant species richness and composition in the Reservoir Protection Strip with adjacent areas, such as the primary forest of the Iguaçu National Park and the Permanent Preservation Area located on a rural property and agricultural areas. In total, 171 ant species were identified. Ant species richness was higher in forest than in agricultural areas and did not differ among forest areas. However, ant species composition in forest areas, regardless of the restoration technique used, was not similar to the primary forest, possibly due to variation in forest recovery time. This study highlights the great value of the Iguaçu National Park as a conservation unit. Also, it reveals that the efforts for the creation and maintenance of the Reservoir Protection Strip, which remains without anthropic interventions for years, might indeed lead to a complete recovery of the ant species composition over time, reinforcing their great importance for biodiversity conservation. [ABSTRACT FROM AUTHOR]

Many old fields are undergoing ecological restoration aiming to return lost biodiversity and ecosystem functions. However, there is scant evidence that this outcome is achieved. Here we investigate the effects of tree planting following cessation of cropping on ant communities. Ants are a dominant faunal group, functionally important for ecosystem recovery and widely used as indicators of ecosystem restoration. Using a space‐for‐time approach, we surveyed eight fallow croplands, 10‐year‐old planted old fields, and reference woodlands in semi‐arid south‐western Australia. We tested the extent ant communities in planted old fields diverged from those of fallow cropland and converged with those of reference woodlands, distinguishing areas under tree canopies and open patches to account for a direct tree effect. We analyzed ant community data at species, genus, and functional‐group levels. Ant species composition in planted old fields substantially converged from fallow croplands toward reference woodlands. Abundance and richness of genera in the tree‐associated functional group Subordinate Camponotini was higher under trees than in open areas in planted old fields and reference woodlands. Unlike in reference woodlands, abundance and richness of Hot Climate Specialists was not higher in open areas than under trees in planted old fields, indicating that planted trees did not yet strongly impact the microclimate beneath them. Although old field restoration had positive effects on ant assemblages, full convergence to reference woodlands had not been achieved after 10 years. This was particularly evident for functional groups. Research on older plantings is needed to test if and when full convergence occurs. [ABSTRACT FROM AUTHOR]

Landscape changes in tropical environments result in long-lasting and complex changes in biodiversity that involve several biological responses (e.g., loss of species diversity and functional diversity). Both taxonomic and functional diversity might respond differently to land-use change, and this response might also vary depending on several factors, such as the taxonomic group or landscape context. Even though each level of diversity expresses different properties of the community structure, studies characterizing the species community in human-dominated landscapes have often only focused on patterns involving taxonomic diversity. Here, we evaluated different descriptors of taxonomic (i.e., richness, diversity, and dominance) and functional entropy (i.e., richness, diversity, and redundancy) and the taxonomic and functional composition of ants in a forest cover gradient (%) in 16 highly fragmented tropical humid forest landscapes in Mexico. We found that all descriptors of taxonomic diversity decreased along a gradient of forest loss. Furthermore, functional redundancy was the only component of functional diversity that was positively associated with forest cover (%). These findings suggest an ecological backup of functions provided by species in landscapes with higher forest cover, protecting these landscapes against habitat disturbance or species loss. We also observed that landscapes with larger forest cover were inhabited by ant species with larger interocular distances and smaller femurs, which could allow predator ants the exploitation of ground cracks and higher mobility in leaf-litter microhabitats. Our results highlight the importance of the primary forest as a reservoir of the taxonomic and functional diversity of ants in highly fragmented tropical rainforest landscapes. [ABSTRACT FROM AUTHOR]

We explored the structure of plant assemblages that settles around the anthills of a guild of Hymenoptera Formicidae (Messor wasmanni Krausse 1910, Tapinoma nigerrimum Nylander 1856 and Aphaenogaster spinosa Emery 1878), observable in urban grasslands dominated by Dasypyrum villosum (Rome, Central Italy). Since it is known that ants act as a disturbing factor on plant assemblages of grasslands, our hypothesis was that vegetation structures suffer from some stressors that affect, in this plant association, the dominant plant structure. We compared the plant assemblages observed in the plots of the anthills with the control grassland assemblages using a diversity/dominance diagram. We recorded 63 plant taxa. The average number of plant species was found to be significantly lower in anthill plots than in control grassland plots. In anthill plots, dominant plant species (Polygonum romanum, Poa trivialis Vulpia myuros, Aira elegantissima and Vulpia ligustica) have been found to be different from control grassland plots (Convolvolus arvensis, Dasypyrum villosum, Poa trivialis and Sheradia arvensis). Anthill plant assemblages were found to be significantly different (One-way PERMANOVA) and poorer in terms of species richness, less diversified, and with a reduced species turnover than control grassland plots. Whittaker plot analysis seems to show that the plant assemblages of the control, with greater evenness, emphasize a stressed condition in anthill plant assemblages. Non-metric multidimensional scaling shows a set of species strictly linked to anthills. Our data seem to confirm the role of ants as a stressor in the plant assemblage structures of Mediterranean urban grasslands. However, our results also show that the peculiar ant nest conditions may favor plant species less represented in the Dasypyretum grasslands (i.e. Polygonum romanum) or even absent in this plant assemblage (i.e. Aira elegantissima, Cynodon dactylon and Poa annua), thus increasing the overall local plant diversity. [ABSTRACT FROM AUTHOR]

Major shifts in the availability of palatable plant resources are of key relevance to the ecology of leaf-cutting ants in human-modified landscapes. However, our knowledge is still limited regarding the ability of these ants to adjust their foraging strategy to dynamic environments. Here, we examine a set of forest stand attributes acting as modulating forces for the spatiotemporal architecture of foraging trail networks developed by Atta cephalotes L. ( Hymenoptera: Formicidae: Attini). During a 12-month period, we mapped the foraging systems of 12 colonies located in Atlantic forest patches with differing size, regeneration age, and abundance of pioneer plants, and examined the variation in five trail system attributes (number of trails, branching points, leaf sources, linear foraging distance, and trail complexity) in response to these patch-related variables. Both the month-to-month differences (depicted in annual trail maps) and the steadily accumulating number of trails, trail-branching points, leaf sources, and linear foraging distance illustrated the dynamic nature of spatial foraging and trail complexity. Most measures of trail architecture correlated positively with the number of pioneer trees across the secondary forest patches, but no effects from patch age and size were observed (except for number of leaf sources). Trail system complexity (measured as fractal dimension; Df index) varied from 1.114 to 1.277 along the 12 months through which ant foraging was monitored, with a marginal trend to increase with the abundance of pioneer stems. Our results suggest that some leaf-cutting ant species are able to generate highly flexible trail networks (via fine-tuned adjustment of foraging patterns), allowing them to profit from the continuous emergence/recruitment of palatable resources. [ABSTRACT FROM AUTHOR]

Leaf-cutting ants ( LCA) are polyphagous and dominant herbivores throughout the Neotropics that carefully select plant individuals or plant parts to feed their symbiotic fungus. Although many species-specific leaf traits have been identified as criteria for the choice of food plants, the factors driving intraspecific herbivory patterns in LCA are less well studied. Herein, we evaluate whether or not drought-stressed native plants are a preferred food source using free-living colonies of two leaf-cutting ants, Atta sexdens L. ( Hymenoptera: Formicidae: Attini), in combination with five plant species, Ocotea glomerata Nees ( Lauraceae), Lecythis lurida S. A. Mori ( Lecythidaceae), Miconia prasina DC ( Melastomataceae), Tovomita brevistaminea Engl. ( Clusiaceae), and Tapirira guianensis Aubl. ( Anacardiaceae), and Atta cephalotes L., in combination with two plant species, O. glomerata and Licania tomentosa Benth. ( Chrysobalanaceae). In dual-choice bioassays, ants removed about three times more leaf area from drought-stressed plants compared to control plants. Both leaf-cutting ant species consistently preferred drought-stressed plants for all species tested, except T. guianensis. The mean acceptability index - expressing the preference for one of two options on a scale of 0 to 1 - of drought-stressed plants ranged from 0.65 to 0.86 across plant species, and the preference did not differ significantly among the tested plant species. Our results suggest that selection of drought-stressed individuals is a general feature of food plant choice by leaf-cutting ants irrespective of ant or plant species. As human-modified forest assemblages across the Neotropics are increasingly prone to drought stress, the documented preference of Atta for drought-stressed plants may have tangible ecological implications. [ABSTRACT FROM AUTHOR]

Understanding how communities respond to anthropogenic disturbance is considered a stepping-stone to support decision-making by environmental managers and restoration ecology. In endangered biodiverse regions, such as the Neotropics, ecological indicators are particularly useful, by enlighten possible diversity trends and functional shifts. Our objectives were to deepen our understanding on the soil ant assemblages/habitat relationships in the Brazilian Amazon, particularly relevant for a data-deficient and fast changing region, and evaluate if regional ant assemblages, collected within a gradient of disturbance, could fulfill the surrogate role. A sampling effort of 630 pitfall traps and litter collection were used for monitoring ant communities within the gradient of habitats considered. Sequential reductions in ant richness, abundance and simplification of assemblage compositions were detected along the disturbance gradient comprising pristine forests, secondary forests, agriculture and pastures. Additionally, indicator species identified could be used to assess the disturbance level but also to guide restoration efforts in this region. Finally, even though late secondary forests displayed diverse assemblages, old-growth/pristine forests support distinct communities, highlighting its critical contribution for the conservation of ants. [ABSTRACT FROM AUTHOR]

The fungus-growing ant Mycetomoellerius (previously Trachymyrmex) zeteki (Weber 1940) has been the focus of a wide range of studies examining symbiotic partners, garden pathogens, mating frequencies, and genomics. This is in part due to the ease of collecting colonies from creek embankments and its high abundance in the Panama Canal region. The original description was based on samples collected on Barro Colorado Island (BCI), Panama. However, most subsequent studies have sampled populations on the mainland 15 km southeast of BCI. Herein we show that two sibling ant species live in sympatry on the mainland: Mycetomoellerius mikromelanos Cardenas, Schultz, & Adams and M. zeteki. This distinction was originally based on behavioral differences of workers in the field and on queen morphology (M. mikromelanos workers and queens are smaller and black while those of M. zeteki are larger and red). Authors frequently refer to either species as "M. cf. zeteki," indicating uncertainty about identity. We used an integrative taxonomic approach to resolve this, examining worker behavior, chemical profiles of worker volatiles, molecular markers, and morphology of all castes. For the latter, we used conventional taxonomic indicators from nine measurements, six extrapolated indices, and morphological characters. We document a new observation of a Diapriinae (Hymenoptera: Diapriidae) parasitoid wasp parasitizingM. zeteki. Finally, we discuss the importance of vouchering in dependable, accessible museum collections and provide a table of previously published papers to clarify the usage of the name T. zeteki. We found that most reports of M. zeteki or M. cf. zeteki-including a genome-actually refer to the new species M. mikromelanos. [ABSTRACT FROM AUTHOR]

Several studies have evaluated the impacts of intensified human activities on biodiversity, but far less effort has been directed toward evaluating the maintenance of ecosystem functions in human-modified landscapes. We investigated the impacts of habitat shifts from forest to pasture on assemblages of seed-removing ants in the southwestern Brazilian Amazon. We specifically addressed the following hypotheses regarding assemblages of seed-removing ants: (i) pasture ant assemblages have fewer species than do forest ant assemblages and are composed of a markedly different set of species; (ii) pasture ant assemblages remove less seeds than do forest ant assemblages; and (iii) forest and pasture ant assemblages contain different sets of key species for seed removal. We collected ants that were baited with artificial seeds in 10 forest areas and 10 adjacent pastures and found that shifting from forest to pasture reduced the number of species of seed-removing ants and altered species composition. We also found that, although seed removal percentage of was higher in pasture, these species were low quality seed dispersers, which was supported by our identification of key species for seed removal. We conclude that when considering the removal of seeds by ants as a proxy to assess the role of biodiversity in ecosystems, it is necessary to consider the importance of each species for removal according to habitat type affinity. Implications for insect conservation: Our findings highlight the importance of forest habitat for the effective conservation of ant diversity and their ecological functions in human-modified ladscapes. [ABSTRACT FROM AUTHOR]

The Brazilian savanna (Cerrado biome), now reduced to about 173,500 km2 of its original two million km2 range, is one of the most threatened biomes in the world. In the meridional limit of this biome is the Cerrado State Park (CSP), state of Paraná, Brazil, the only savanna conservation unit in Southern Brazil. This survey of the arboreal and ground-dwelling ants of the park obtained 136 species in 36 genera and eight subfamilies, an expressive diversity given the size, degree of isolation and location of the park. There was a high stratification of the ant community with a dominance of ground-dwelling species. Camponotus crispulus, Pheidole exigua, and Pheidole scapulata are new records for Southern Brazil. The ponerine genus Mayaponera and 13 species from several genera are recorded for the first time for the state of Paraná. The great number of ant species found and the presence of rarely collected elements of the Neotropical ant fauna indicate that this is one of the most diverse areas of savanna in Brazil. However, the CSP is severely threatened by anthropic activities, such as monocultures, cultivation of exotic plants, and livestock. Even more concerning is a recent new law approved by the government of Paraná that allows the touristic exploitation of reserves like the CSP by private companies. If an effective conservation effort to preserve the park area is not taken, we will certainly witness the extinction of the last assembly of ants from the Brazilian Cerrado in Southern Brazil, along with other elements of the biodiversity associated with the CSP. [ABSTRACT FROM AUTHOR]

Habitat loss is a leading cause of extinctions, which may occur even before species are recorded or formally described. On the other hand, limitations in species distribution data and sampling biases can hamper inferences about patterns of species richness that form the basis of conservation strategies. Insects, despite their crucial roles in terrestrial ecosystems, are still largely neglected when dealing with biological inventories. Among insects, ants are of unique importance because of their species richness, widespread distribution, and due to their key ecosystem functions such as seed dispersal, soil nutrient cycling, predation, and biological control. In this study, we prioritize different Brazilian biomes and ecoregions for new ant surveys based on information on the distribution of occurrence records and two estimates of habitat loss for the period between 2000 and 2016. We compiled nearly 8000 ant occurrence records, including a total of 1170 species. The Caatinga was the biome showing the greatest urgency for new inventories, whereas the Atlantic Forest had the lowest urgency. However, there were considerable differences of priority between ecoregions belonging to each biome, thus underscoring the need to pay special attention to these geographical units and their characteristic associated with ant species. The prioritization of poorly studied sites with an imminent risk of habitat loss can be a valuable starting point for filling knowledge gaps and can help in formulating new strategies of conservation. The dataset provided here may also be useful in studies on the distribution of ant diversity in Brazil. [ABSTRACT FROM AUTHOR]

Phorid flies (Diptera: Phoridae, Metopinini) are natural enemies of leafcutter ants (Hymenoptera: Formicidae, Attini), which are among the most important pests in the Neotropical region. These parasitoids lay their eggs inside worker ants, causing the death of the parasitized ants, and the oviposition attacks on foraging workers interfere with the collection of vegetal material used in fungal gardens, thereby affecting the whole colony. However, because of the large number of ants per colony, more than one type of biological control agent is needed to have a significant impact. We collected parasitized leafcutter ants Acromyrmex lundii (Guérin‐Méneville), Acromyrmex heyeri (Forel), and Acromyrmex ambiguus (Emery) from various places in Argentina and reared their parasitoids. We recorded developmental times, host and phorid sizes, and other aspects of the biology of the phorids Apocephalus neivai Borgmeier, Apocephalus noetingerorum Brown & Disney, Myrmosicarius gracilipes Borgmeier, Myrmosicarius catharinensis Borgmeier, Myrmosicarius crudelis Borgmeier, and Myrmosicarius cristobalensis Disney et al. This is the first record of A. ambiguus, an important pest of pine plantations, being a host of phorids. We found the first cases of gregarious parasitoidism of a parasitoid with no‐free pupae: M. catharinensis on A. lundii ants. We also evaluated the effect on pupal survival of two cosmopolitan fungi, Beauveria bassiana (Balsamo) Vuill. and Trichoderma lentiforme (Rehm) Chaverri et al., which are also considered as potential biological control agents of leafcutter ants. Suspensions of conidia were tested on Myrmosicarius and Apocephalus parasitoid pupae of different ages. No negative effect on pupal survival was found under either fungal treatment. Therefore, the use of both natural enemies separately but simultaneously, or the introduction of fungi‐inoculated pupae in the pest habitats, seems to be a promising strategy for the multiple biological control of leafcutter ants. [ABSTRACT FROM AUTHOR]

Urban green recreational spaces may provide habitat for animals and plants. We investigated the importance of urban public parks in the city of Rio de Janeiro with regard to the conservation of ant species by comparing both the structure of the ground-dwelling ant community between urban parks and continuous forests and the influence of environmental factors on possible differences. Fifteen urban areas were sampled (5 isolated parks, 5 non-isolated parks and 5 forest areas). Ants were sampled at sardine bait stations and through manual/visual searching in quadrats around the baits. We identified 120 ant species (4 exotic species) distributed across 38 genera and 7 subfamilies. The four exotic species were Monomorium floricola, Paratrechina longicornis, Pheidole megacephala and Tetramorium simillimum. Both the taxonomic and functional diversity of ground-dwelling ants were higher in continuous forests, followed by non-isolated and then isolated urban parks. Environmental factors were found to be key drivers influencing the differences in ant community structure among continuous forests and urban parks. Soil compaction and canopy cover predicted the diversity patterns of the taxonomic and functional compositions of the ant communities. The ant species in the study areas exhibited a non-random pattern of distribution and a spatial association of species segregation. There was high spatial turnover of ant species in the study areas, indicating that conservation efforts are required in all studied urban areas, not just those areas considered to be species rich. Therefore, we need to conserve more species in more areas, not necessarily those high in richness. [ABSTRACT FROM AUTHOR]

Ant inquiline social parasites obligately depend on their hosts for survival and reproduction. Because of their shift from a eusocial to a socially parasitic life history, inquiline social parasites are interesting study systems for exploring the dynamics between conflict and cooperation in eusocial insect colonies. In addition, inquiline social parasites are of interest to evolutionary biology, because some species evolved directly from their hosts via sympatric speciation. With five described species, inquiline social parasites are relatively diverse in the fungus-growing ants. So far, four species have been reported from the leaf-cutting ant genus Acromyrmex and its closely affiliated social parasite genus Pseudoatta. In contrast, only a single parasite species was described from the lower attine genus Mycocepurus. Here, we describe a new species of inquiline social parasite, Acromyrmex fowleri sp. nov., which was discovered 27 years ago in the tropical region of Brazil (State of Bahia), living inside the colonies of its host Acromyrmex rugosus. We also report observations on the behavioral ecology and natural history of A. fowleri and its host. Our study suggests that A. fowleri is an obligate, queen-tolerant, workerless inquiline social parasite of A. rugosus and that A. fowleri represents some but not all morphological and life history characters of the inquiline syndrome, supporting the hypothesis that the complex traits of the inquiline syndrome evolve in a mosaic fashion. Considering that A. fowleri is a new social parasite species from tropical Brazil, we discuss the paradoxical biogeographic distribution of ant social parasites, which we refer to as the "Kutter–Wilson Paradox", and conclude that the Kutter–Wilson Paradox is a genuine biogeographical pattern, instead of being a mere sampling artifact. [ABSTRACT FROM AUTHOR]

One of the most effective means of evaluating the effects of habitat loss and landscape configuration is to assess the response of bioindicators. The present study aimed to verify which parameters of ant and dung beetle communities (species richness, abundance, unbiased Shannon diversity, and turnover rates) are most useful for evaluating the relative influence of small forest patches (< 50 ha) and landscape in the tropical rainforest of Los Tuxtlas, Mexico. We recorded a total of 106 species of ants and 30 species of dung beetle. The ant and dung beetle assemblages were related in different ways to patch and landscape attributes. Hypogeic ants were more sensitive to patch attributes, particularly vegetation composition, compared to landscape attributes. Epigeic ant assemblages are likely a disturbance indicator, or the assemblages have already homogenized across the region. Arboreal ant assemblages were particularly sensitive to fragmentation and responded to within-patch vegetation and landscape configuration. Dung beetles were more sensitive to landscape composition than to patch attributes. Given these findings, the biomonitoring of ants and dung beetles should focus on both patch and landscape attributes in fragmented landscapes to maintain the different ecosystem functions provided by them. [ABSTRACT FROM AUTHOR]

The main effects of habitat loss and fragmentation have been addressed through changes in diversity patterns at different spatial levels. Species richness and diversity are the most used descriptors to assess the effect of changes in land use on tropical communities. However, other biological responses such as richness and diversity of trophic guilds may also provide a better understanding about the robustness and resilience of tropical environments to disturbance. In this study, we evaluated how changes in local and landscape characteristics associated to habitat loss and fragmentation affect: (i) species richness and Shannon diversity as well as (ii) trophic guild richness and diversity of leaf litter ants in human-modified tropical rainforest landscapes in Mexico. For this, we sampled ants in 16 sampling sites and recorded a series of descriptors at both local (i.e. elevation, temperature, relative humidity, soil pH, canopy cover, litter volume and vegetation structure) and landscape level (i.e. landscape heterogeneity, forest cover and connectivity). Overall, we observed that increasing primary forest cover within the sampling sites positively influenced richness and diversity of species and trophic guilds. In addition, at the local level, we found that only richness and diversity of ant species were negatively associated with tree density (i.e. number of trees, litter volume and canopy cover). These findings suggest that opportunistic species can be favored in environments with low tree density. In short, our complementary approach highlights the importance of environmental variability and primary forest cover in the maintenance of ant biodiversity in primary rainforest remnants. [ABSTRACT FROM AUTHOR]

Over 40 years ago, the dacetine ant Strumigenys arizonica was discovered in a nest of the fungus-growing ant Trachymyrmex arizonensis at Madera Canyon in the Santa Rita Mountains of the southwestern United States. This discovery suggested that the two species form compound nests, but this hypothesis has not been investigated. Here, we characterize this symbiosis through an analysis of collection records supplemented by recent field and laboratory observations. Our observations show that S. arizonica and T. arizonensis form compound nests that are a type of commensalistic symbiosis. Individuals of S. arizonica forage in galleries and tunnels of T. arizonensis nests but do not steal fungus or brood. Instead, individuals of S. arizonica hunt collembolans in the internal refuse piles of T. arizonensis nests. Interestingly, S. arizonica was never found independent of its host T. arizonensis over a significant portion of the geographic range of T. arizonensis. These results suggest a tight but asymmetric association where compound nesting is obligate for S. arizonica and facultative for T. arizonensis. [ABSTRACT FROM AUTHOR]

Habitat fragmentation can have a high impact on parasitoid-ant interactions. Phorid flies are among the most important groups of natural enemies of leaf-cutting ants. We studied the effects of loss in forest cover upon phorids of the leaf-cutting ant Acromyrmex niger Smith ( Hymenoptera: Formicidae: Attini) in a fragmented area in the Southeastern Atlantic Forest, Brazil. We sampled 10 forest fragments, five large (>75 ha) and five small (<20 ha), as well as three areas of continuous forest (>1 000 ha). We marked 1-5 colonies of A. niger in the interior of each forest location. At each nest, we collected all of the phorids in interaction with the worker ants for a period of 15 min. We then collected ca. 200 worker ants, which we maintained in the laboratory for rearing phorids from them. We identified three phorid genera - Apocephalus, Myrmosicarius, and Neodohrniphora - which we both observed in the field and reared in the laboratory. The abundance and parasitism percentage were significantly greater in continuous forest sites than in forest fragments, whereas there were no significant differences between fragments of different sizes. These results provide further evidence for the effects of habitat size on the phorid- Acromyrmex system in a tropical rain forest, based on the abundance of parasitoids both as adults in the field and as reared immature phorids in the laboratory. [ABSTRACT FROM AUTHOR]

While swamps perform valuable functions in coastal ecosystems, terrestrial invertebrates in these fragile habitats are poorly known. The aims of this study were to (1) uncover the ant diversity and functional groups of Cypress-Tupelo swamps; (2) examine the differences of ant assemblages across vertical strata within trees and across tree species within swamps; and (3) determine if the ant mosaic hypothesis applies to observed patterns of arboreal ant distribution. Pitfall traps were set in tree crowns and on trunks to collect the arboreal ants in three swamps in Louisiana. A total of 21 species from 11 genera were collected. Contrary to our hypothesis, ant diversity on trunks was higher than that in the canopy. A multivariate analysis revealed that the canopy and trunk support distinct ant assemblages, whereas ant species composition was not consistently different among the three dominant tree species- bald cypress, water tupelo, and red maples. In addition, evidence of ant mosaic distribution patterns were not detected. Moreover, we did not find dramatic changes of ant diversity or community structure in trees that were infested with invasive red imported fire ants. Our study provides a benchmark to evaluate the effects of disturbances and conservation management in swamp ecosystems. [ABSTRACT FROM AUTHOR]

An organism's morphology is constrained by its evolutionary history and the need to meet a variety of potentially competing functions. The ant genus Pheidole is the most species-rich ant genus and almost every species has a dimorphic worker caste (a few are trimorphic). This separation of workers into two developmentally distinct subcastes (smaller minors and larger majors with distinctively large heads) may partially release individuals from functional constraints on morphology, making Pheidole an ideal genus for addressing questions on the evolution of morphology in relation to ecological specialization. Major workers can perform a variety of tasks, although they are usually specialized for defence, as well as food retrieval and processing. Pheidole species vary in their diet, although many species gather seeds. The major workers mill the seeds using large jaws powered by mandible closer muscles that occupy a large proportion of the head cavity. In the present study, we examined the relationship between seed-harvesting and morphology in Pheidole, hypothesizing that majors of seed-harvesting species would have larger heads relative to non-seed-harvesters to accommodate the powerful mandibular muscles needed to mill seeds. By taking a phylogenetically controlled comparative approach, we found that majors of seed-associated Pheidole did not have larger heads (width and length) than majors of non-seed-harvesting species. However, the head length of minors (and to a lesser extent head width) was smaller in seed-harvesters. Additionally, we found the difference in head size between majors and minors was greater in seed-harvesting species. These morphological differences in diet, however, were not related to changes in the rate of evolution in either seed-harvesting or non-seed-harvesting lineages. These findings suggest that the morphologies of worker subcastes can evolve independently of each other, allowing colonies with polymorphic workers to specialize on new resources or tasks in ways not possible in monomorphic species. [ABSTRACT FROM AUTHOR]

One of the main concerns when collecting data is the bias stemming from the researchers' expertise and training. The precision and accuracy of the data being collected can vary depending on the focus, concentration, mood, and experience of a researcher, and this can generate errors in data collection that can influence the results. We present a software for counting leaf-cutting ants that tracks the number of ants on previously recorded videos. The software was developed in the Python language and uses an image processing library called OpenCV (Open Source Computer Vision). It is based on a low-resolution video (640 × 480 pixels) taken with a camera mounted on a tripod and orientated perpendicularly to the ground. This open access program uses the movement of ants to identify their position and track them. It counts the number of ants that pass through a given point in two directions with respect to the nest entrance: incoming and outgoing. Comparisons between AntCounter and conventional methods used to count ants show that the program has higher accuracy than traditional counting in real time while reducing data collection time. We also report the error in the data collected by AntCounter. Using AntCounter the researcher reduces both the time of data collection in the field and the time to process data. It is also possible to improve the sampling effort (e.g., increase the number of samples, the number of experimental units), and measure the ants for longer periods of time, and at lower prices. [ABSTRACT FROM AUTHOR]

Fluctuating resources and conditions can regulate the community structure of ants, affecting their activities and interactions. This has important implications for the selection of sampling periods during bioindication studies. The aim of this study was to evaluate if the chosen sampling period influences the response of ant assemblage diversity and ecological function to mining impacts and rehabilitation age after mining. We used ant assemblage parameters, including arboreal, epigaeic and hypogaeic ant species richness and composition, seed-removing ant species richness and composition, and seed removal rate in areas impacted by mining and with different rehabilitation ages. We showed that in most cases the response is the same, regardless of sampling period. However, we suggest that ant sampling is best undertaken in the rainy period, when ant species richness reaches higher values and the assemblage composition presents a well-marked difference among the areas. We also indicate that the epigaeic ant assemblage is sufficient for evaluating mining impacts, but arboreal strata should also be sampled in rehabilitation scenarios. [ABSTRACT FROM AUTHOR]

As a self-organizing entity, an ant colony must divide a limited number of workers among numerous competing functions. Adaptive patterns of labor allocation should vary with colony need across each annual cycle, but remain almost entirely undescribed in ants. Allocation to foraging in 55 field colonies of the Florida harvester ant ( Pogonomyrmex badius) followed a consistent annual pattern over 4 years. Foragers preceded larvae in spring and peaked during maximal larval production in summer (0.37). In spring, proportion foraging increased due to an increase in forager number and reduction in colony size, and in late summer, it decreased as colony size increased through new worker birth and a loss of ∼3 % of foragers per day. The removal of 50 % of the forager population revealed that, at the expense of larval survival, colonies did not draw workers from other castes to fill labor gaps. To determine if labor allocation was age specific, whole colonies were marked with cuticle color-specific wire belts and released, and each cohort's time to first foraging was noted. Workers that eclosed in summer alongside sexual alates darkened quickly and became foragers at ∼43 days of age, whereas autumn-born workers required 200 or more days to do so. Following colony reproduction, these long-lived individuals foraged alongside short-lived, summer-born sisters during the next calendar year. Therefore, the large-scale, predictable patterns of labor allocation in P. badius appear to be driven by bimodal worker development rate and age structure, rather than worker responsiveness to changes in colony demand. [ABSTRACT FROM AUTHOR]

The article discusses the results of a study that determined the impact of non-shaded coffee and pasture agriculture on both the predatory and omnivorous leaf-litter ants of Atlantic Forest in Minas Gerais, Brazil. Compared with pasture, coffee was more disruptive in the leaf-litter ant community. Also coffee negatively affects the number of predatory and omnivorous ants as well as disturbed the diversity of predatory ants.

Ants are a dominant faunal group in tropical forests, but their responses to human disturbances remain poorly investigated. Here we examine the relative effects of habitat fragmentation (fragment size and amount of forest cover retained in the surrounding landscape) and habitat structure (tree density and richness) on ant species and functional composition in the Atlantic forest of northeast Brazil. Our study was carried out in 19 fragments ranging in size from 10 to 3,500 ha. We recorded 146 ant species from 41 genera. Fragment size and tree density were the most important variables predicting species richness and functional diversity. Additionally, fragment area and tree density also explained the richness of a range of global functional groups (Cryptic Species, Specialists Predators and Tropical-climate Specialists) and Atlantic forest functional groups (Cryptic Predators, Cryptic Omnivores, Epigaeic Predators and Epigaeic Omnivores). Taxonomic composition was influenced by fragment area and tree richness, while functional composition responded to forest cover and tree density. Overall variation of global functional groups was also affected by tree richness. Our results suggest that specialist ants (especially cryptic species, specialist predators and climate specialists) are particularly sensitive to forest fragmentation. Such functional groups would make useful indicators of ant responses to forest fragmentation. [ABSTRACT FROM AUTHOR]

Myrmecochory or seed dispersal by ants is often described as a diffuse mutualism, because many of the ant species that function as partners are considered to be similar in terms of the frequency and consequences of their interactions. In this work, we test this assumption by conducting ant community surveys and seed removal experiments in six study sites located within a semi-arid region of northwest Argentina. At each site, we characterized the ant assemblage that interacted with the seeds of Jatropha excisa Griseb. (Euphorbiaceae), an ant-dispersed native shrub. Our results demonstrate that seed removal was dominated by one species, Pogonomyrmex cunicularius Mayr (Hymenoptera: Formicidae: Myrmicinae), which was responsible of 84% of the observed seed removal events. Although several ant species were attracted to the elaiosome-bearing seeds of J. excisa, seed removal did not depend on ant community composition (species richness and ant activity) but was significantly influenced by the abundance of P. cunicularius. Its physical, behavioral, and ecological attributes are common with other ant species that have been characterized as keystone seed dispersers in other regions of the world. Nest feeding with marked seeds revealed that once P. cunicularius ants consume the elaiosomes, seeds are left inside the nests undamaged and at an appropriate depth for emergence. Our results support the hypothesis that myrmecochory is often an unevenly diffuse mutualism (i.e., one partner species is particularly important) and that at a local scale P. cunicularius is the keystone seed disperser of J. excisa. [ABSTRACT FROM AUTHOR]

Previous studies have shown that leaf-cutting ant populations benefit greatly from living in or near the edges of the Brazilian Atlantic forest. One of the mechanisms responsible for this rise in population density is an edge-mediated increase of pioneer plants, resulting in increased food availability for the ants (i.e., less bottom-up control). Here, we hypothesized that the release from natural enemies (i.e., less top-down control) may also contribute to the phenomenon. We investigated whether parasitism of phorid flies on leaf-cutting ants decreases in colonies located along the forest edge vs. the interior of a large tract of Atlantic forest in northeastern Brazil. For this, we assessed abundance and rates of oviposition attack by phorids in bimonthly intervals over a period of 1 year in 10 adult colonies of Atta cephalotes (L.) (Hymenoptera: Formicidae: Myrmicinae), five at the forest edge and five in the forest interior. The number of phorids attracted by ants at edge colonies was 40% lower than that at interior colonies. The temporal variation in phorid attraction was also significant, with approximately 35% fewer flies in the dry months as compared to the rainy months. As a result of lower phorid abundance, ant workers of edge colonies suffered three times fewer oviposition attacks than those of interior colonies. There was a tendency for fewer attacks during dry months, but the difference in the temporal variation was not significant. Our findings suggest that edge creation contributes to increased leaf-cutting ant abundance, not only via the attenuation of bottom-up forces, but also through an environmentally triggered depression of parasitoid abundance/efficiency, possibly because of adverse environmental conditions in edge habitats. [ABSTRACT FROM AUTHOR]

Gas chromatographic analyses of volatizable material from gaster intersegmental complex glands of P. tridentata revealed the presence of linoleic acid, palmitic acid, methyl oleate, and several long-chain hydrocarbons as major constituents, which form an oily fluid mixture. The nest relocation communication of P. tridentata is tandem running. Tandem following is mediated by pheromones as demonstrated by dummy experiments with isolated gasters and thoraces and with glass balls. The secretions of all gaster complex glands, as well as hind gut contents and metapleural gland secretions, were unable to evoke tandem following. Morphology and position of the glands, lack of pheromonal function, oily properties, low volatility, and lack of antibiotic effects of these secretions strongly suggest a function as lubricants for the ants' gastral segments. [ABSTRACT FROM AUTHOR]