Ant Diversity Research Articles

An overview of the ant fauna (Hymenoptera: Formicidae) of the state of Maranhão, Brazil

The state of Maranhão, located in northeastern Brazil, comprises three biomes: Amazonian, Caatinga, and the Cerrado. To date, 99 ant species have been recorded in the literature from the state. In the present work, we provide for the first time a profile of the ant fauna in the state based on data from the historical literature and Brazilian institutional collections. The updated records on ant diversity for the state of Maranhão revealed a total of 279 species, belonging to 71 genera and 10 subfamilies. In total, 180 species are recorded for the first time in the state, of which four species recorded for the first time in Brazil. In summary, apart from documenting the ant fauna of the region, these results provide a basis for further studies and may contribute to future conservation efforts for the biomes present in this complex landscape.

The costs and benefits of decentralization and centralization of ant colonies.

A challenge faced by individuals and groups of many species is determining how resources and activities should be spatially distributed: centralized or decentralized. This distribution problem is hard to understand due to the many costs and benefits of each strategy in different settings. Ant colonies are faced by this problem and demonstrate two solutions: 1) centralizing resources in a single nest (monodomy) and 2) decentralizing by spreading resources across many nests (polydomy). Despite the possibilities for using this system to study the centralization/decentralization problem, the trade-offs associated with using either polydomy or monodomy are poorly understood due to a lack of empirical data and cohesive theory. Here, we present a dynamic network model of a population of ant nests which is based on observations of a facultatively polydomous ant species (Formica lugubris). We use the model to test several key hypotheses for costs and benefits of polydomy and monodomy and show that decentralization is advantageous when resource acquisition costs are high, nest size is limited, resources are clustered, and there is a risk of nest destruction, but centralization prevails when resource availability fluctuates and nest size is limited. Our model explains the phylogenetic and ecological diversity of polydomous ants, demonstrates several trade-offs of decentralization and centralization, and provides testable predictions for empirical work on ants and in other systems.

The role of natural vegetation strips in sugarcane monocultures: Ant and bird functional diversity responses

Simplification of landscapes due to the increase of monocultures negatively impacts biodiversity and its functions. In tropical landscapes that are dominated by sugarcane monocultures, some small natural vegetation patches still exist, yet little is known about their capacity to harbor functional biodiversity that may complement agroecological management of the crop. We compared ant and bird diversity in natural vegetation strips to diversity within sugarcane monocultures at increasing distances from the vegetation strips. We also compared functional groups of ants and birds in order to evaluate the role of vegetation strips in regulating pests of economic importance. During two seasons between 2015 and 2016, we studied 12 sites in the Cauca Valley, Colombia, with both natural vegetation strips and sugarcane monoculture and then sampled ants and birds in natural vegetation strips and at four distances towards the interior of the sugarcane matrix (up to 150 m and 350 m respectively). Species richness of ants and birds differed in vegetation strips and sugarcane matrix with decreases in richness as the distance from vegetation strips increased. Furthermore, predatory functional groups of ants and birds were less abundant in the sugarcane matrix, with important implications for key predation services on key sugarcane pests (e.g., Diatraea spp. – Lepidoptera: crambidae). Our results provide evidence that even in highly modified landscapes dominated by monocultures, the conservation of small patches of natural vegetation favors functional biodiversity. Therefore, maintaining and promoting and natural vegetation strips is especially important in highly industrialized monoculture landscapes in order to promote beneficial biodiversity for ecosystem services without sacrificing production area.

DIVERSITAS SEMUT (Hymenoptera : Formicidae) PADA LAHAN GAMBUT DI DESA KUALA DUA KABUPATEN KUBU RAYA

Secondary peatlands located in Kuala Dua Village, Kubu Raya Regency have various types of insects, one of which dominates is ants. Ants are members of the Order of Hymenoptera which have high diversity and complexity as social animals. Ants play a role in spreading seeds, other insect predators, spore spreaders, decomposers, ecological controllers. Information about the diversity of ants in Kubu Raya Regency is still very limited, especially those on peat land in Kuala Dua Village, Kubu Raya District, therefore research on ant diversity needs to be done with the aim to record the diversity of ants on these peatlands. Laying down the observation path is done intentionally (Purposive sampling). The method used is hand collecting and leaf litter sifting. The results shows that seven genera and four subfamily were obtained. Subfamily found is Formicinae, Ponerinae, Myrmicinae, and Dolichoderinae. The Subfamily Formicinae consists of the genus Camponotus, Colobobsis, Polyrhachis, Anoplolepis. The Ponerinae subfamily consists of the genus Leptogenys. Subfamily Myrmicinae consists of the genus Pheidole. The Dolichoderinae subfamily consists of the genus Ecphorella. The diversity index value on line 1 (1.30) is classified as medium category, line 2 (0.80) is classified as low category and line 3 (0.34) is classified as low category. The abundance index on line 1 (0.80) is classified as high category, line 2 (0.73) is classified as low category, line 3 (0.50) is classified as low category. The similarity index of ant species on line 1 and line 2 are (25%) which classified as low category. Line 1 and 3 are (57.14%) classified as medium category. The similarity index of ant species on line 2 and 3 (40%) were also classified as medium category.Keywords: ants, diversity, Kubu Raya District, peat land.

Ant diversity patterns across tropical elevation gradients: effects of sampling method and subcommunity

AbstractLocal diversity may be influenced by niche assembly processes involving competition for limited resources, or by niche conservatism and the length of time clades have had to diversify. Mid‐elevation peaks in ant diversity on wet forest elevational gradients are most consistent with niche conservatism effects. However, it is possible that subsets of the ant community vary in the degree to which niche assembly processes are important, and this may be revealed by sampling methods that bias toward particular subsets. A previous study of ant‐elevation patterns in Middle American wet forest relied on Winkler sampling, a method that samples much of the ant community that occurs in leaf litter and rotten wood on the forest floor. Here, we evaluate richness patterns at the same sites as the previous study, using two alternative methods: baiting and beating. Baiting attracts ants to a concentrated resource and might be expected to attract a community more shaped by competitive interactions. Diversity patterns at baits were nearly identical to patterns from Winkler samples, for all ants combined and for the genus Pheidole, which are abundant omnivorous ants that are among the most common at baits. There was no evidence that stronger competitive effects influenced the shape of the diversity curve. Beating samples capture ants that forage on low vegetation, a distinct arboreal community with lower phylogenetic diversity than litter ants and inhabiting a more variable microclimate. Arboreal ants differed from litter ants in having a less distinct mid‐elevation peak, with less of a decline from 500 m to sea level. The lowland decline in litter ant diversity may be caused by the recent upslope shift in temperature associated with the current interglacial period. Arboreal ants may be buffered from this effect by adaptation to canopy life, tolerating broader extremes of temperature, or by high rates of dispersal from warmer regions.

Secondary succession has surprisingly low impact on arboreal ant communities in tropical montane rainforest

AbstractUnderstanding forest regeneration processes is increasingly important as disturbed forests spread rapidly in tropical landscapes. While successional dynamics are relatively well‐understood for plants, they remain poorly known for tropical insects, particularly in montane rainforests and tree canopies. We studied the effect of montane forest succession on arboreal ant communities in New Guinea near their natural elevational limit (1800 m a.s.l.). We censused ant species and nests in replicated 0.1‐ha plots of primary, old and young secondary forests, destined to be felled for gardens by the local landowners. Overall, 1249 felled trees were dissected for all ant‐associated microhabitats. We used rarefaction‐based models manipulating vegetation structure and multivariate randomizations to assess the effects of tree density, tree size, and nesting microhabitats on the ant communities. We expected increased ant species diversity, microhabitat specialization, and species turnover among trees throughout the succession, with distinct community composition among the stages. In contrast to our expectations, ant species composition and diversity per plot did not change during succession, and species similarity among trees was significantly higher only in old secondary forest. The number of ant species per tree increased with forest age, but trees of similar size hosted only slightly more species in primary than secondary forests. Many ant species were associated with particular nesting microhabitats; however, the same microhabitat types occurred in all stages and thus did not generate successional trends in ant communities. Secondary succession had an unexpectedly low impact on tree‐dwelling ant communities in this montane ecosystem, in contrast with our previous findings from lowland rainforests. These results highlight the need to study successional processes along entire elevational gradients, as montane taxa may react differently to vegetation changes than their lowland counterparts.

A new species and new record of the cryptobiotic ant genus Ponera Latreille, 1804 (Hymenoptera, Formicidae) from Hong Kong.

Despite its small size, Hong Kong hosts a surprising level of ant diversity. Through faunal studies on arthropods conducted in Hong Kong over recent years, a new record and species of the genus Ponera have been discovered, which are introduced here. Ponera guangxiensis Zhou, 2001 is reported for the first time from Hong Kong, and Ponera tudigongsp. nov. is here described as a new species, easily distinguishable from other Ponera species and unique within the genus for its four mandibular teeth.

Diversity of Ants and Termites of the Botanical Garden of the University of Lomé, Togo.

Ants and termites are used as bioindicators in many ecosystems. Little knowledge is available about them in Togo, especially ants. This study aimed to find out how ants and termites could be used to assess the restoration of former agricultural land. These insect groups were sampled within six transects of 50 × 2 m2 (using pitfall traps, monoliths, baits for ants and hand sampling for termites) in two consecutive habitats: open area (grassland) and covered area (an artificial forest). Seventeen termite species and 43 ant species were collected. Seven ant species were specific to the covered area against four for the open area, while four unshared species of termite were found in the open area against three in the covered area. The presence of unshared species was linked to vegetation, as Trinervitermes (Holmgren, 1912), a grass feeding termite, was solely found in open area. Also, for some ant species like Cataulacus traegaordhi (Santschi, 1914), Crematogaster (Lund, 1831) species, Oecophylla longinoda (Latreille, 1802) and Tetraponera mocquerysi (Brown, 1960), all arboreal species, vegetation was a determining factor for their presence. The occurrence of these species together with Basidentitermes mactus (Sjöstedt, 1911), Strumigenys bernardi (Brown, 1960) and S. sistrura (Bolton, 1983), suggest a more advanced level of restoration of the covered area.

ANTS OF GRENADA (HYMENOPTERA, FORMICIDAE)

On West Indian islands, as elsewhere in the world, ants are a very important component of virtually every terrestrial ecosystem. Nonetheless, the ants of most West Indian islands have remained largely unknown and unstudied. Now several destructive exotic ant species are spreading through the region, threatening native biodiversity. Here, we have compiled published and unpublished ant records and collected new specimens to document the diversity of ants on the island of Grenada. Our investigations increased the list of ant taxa known from the island to 82 (65 New World and 17 Old World species). Of these, 71 species are represented among specimens we collected, whereas 11 are New World species known from Grenada solely on the basis of earlier records. Some species recorded earlier, including at least nine not seen for more than 100 years, may now be extinct on Grenada. Grenada has more New World ant species than are known for Barbados (46), a neighboring island that has 34% more land area. Factors that may contribute to this difference include: 1) during low sea levels 15,000 years ago, Grenada was part of a larger island about 10 times Grenada's current size; 2) Grenada is more mountainous than Barbados; and 3) Grenada has more remaining forest cover than Barbados (50.0% vs. 14.7%). Conversely, Grenada has fewer Old World ant species than are known for Barbados (24). Factors that may contribute to this difference include: 1) lower human population density, 2) lower levels of imported lumber products, and 3) lower tourism levels. Records for only four of the 17 Old World exotic ants found in Grenada date to before 1995. Major tramp ant species that are known from the West Indies but have not yet been recorded from Grenada include Old World species such as the pharaoh ant (Monomorium pharaonis), the African big-headed ant (Pheidole megacephala), and the difficult white-footed ant (Technomyrmex difficilis), as well as the red imported fire ant (Solenopsis invicta).

Diversity of ants (Hymenoptera, Formicidae) along a heavy metal pollution gradient: Evidence of a hump-shaped effect

Abstract Ants, as indicators of ecological changes, are widely used in land management and environmental monitoring. At the same time, effects of industrial pollution are less known compared to many other stressors. We studied variations in habitat variables and ant diversity near the Karabash copper smelter (KCS) in Russia, in 2009 and 2014. Pitfall traps were set up at 10 birch forest sites (3 plots per site and 5 traps per plot) located to the north and south of the smelter within a 1–32-km range, with two samplings per season (June and August). The tree height, stand basal area, species richness of the field and moss layers, and the cover of the field layer decreased towards the smelter. The vegetation almost disappeared at the industrial barren close to KCS. In total, 21 ant species of 7 genera were registered. The highest species richness, diversity, and total occurrence of ants were observed in the transitional zone between moderately polluted forest habitats and industrial barren. Ant diversity and occurrence showed the same pattern in different years. Our results conform to the intermediate disturbance hypothesis predicting the greatest diversity at intermediate frequencies or intensities of disturbance or environmental change. Apparently, contaminant exposure affects ant communities near KCS indirectly, through habitat transformation. The study emphasizes the need for thorough planning of field studies of pollution effects on ants with examination of the full range of exposures. In addition, the nonlinear pattern of diversity and abundance of the ant community along the pollution gradients suggests caution, when assessing the magnitude of human impact and the state of ecosystems with ants as bioindicators.

KEANEKARAGAMAN SEMUT (Famili Formicidae) PADA LAHAN GAMBUT DI LINGKUNGAN GEDUNG BARU FAKULTAS KEHUTANAN UNIVERSITAS TANJUNGPURA PONTIANAK

Ants have an important role in an ecosystem such as seed spreaders, pollinators, decomposers, and soil growers. Ants can live on peatlands that have acidic pH. The new building of the Faculty of Forestry is an area of peatland where there is one of the fauna, namely ants. The ants in the environment of the Faculty of Forestry’s new biulding are unknown. The research aims to record the types of ants found on peatland in the environment of the new building of the Faculty of Forestry, Tanjungpura University. Takingthe samples of ants was done with sifting hand collecting and leaf litter sifting methods. This study found 4 subfamilies and 7 genera of ants. The subfamilies found were Subfamily Formicinae consisting of the genera Anoplolepis, Camponotus, Echinopla, and Polyrhachis, Subfamily Ponerinae consisting of Genus Diacamma; Subfamily Pseudomyrmecinae consisting of genus Tetraponera; and Subfamily Myrmicinae consisting of the Crematogaster Genus. Diversity index has a value of H ̅ = 1.44 which indicates that the research location has moderate diversity. The overall index of species richness has a DMg value = 5.58 indicating the wealth of ant species is in the high category. Evenness index with a value of 0.73, evenness of ant species is quite even. Keywords: Diversity of ants, Faculty of Forestry, Family Formicidae, Peatlands

Effects of Urbanization on the Diversity, Abundance, and Composition of Ant Assemblages in an Arid City.

Cities within arid regions make up a significant but understudied subset of the urban ecosystems of the world. To assess the effects of urbanization, fragmentation, and land-use change in an arid city, we sampled the ant assemblages in three habitat types in Tucson, Arizona: irrigated neighborhood parks, urban desert remnants, and preserved desert. We analyzed the abundance, species richness, evenness, as well as the species and functional group composition of ant assemblages. We found no significant differences in species richness or evenness. However, irrigated parks had significantly greater ant abundances. Although some exotic species were present in the urban habitats, they did not have significant effects on ant diversity. Ant assemblages from all three habitat types were distinct from each other in their composition. Irrigated parks included a significantly higher proportion of species typically found in cooler and wetter climates. The differences in abundance and species composition between irrigated parks and the other habitats are likely the effect of irrigation removing water as a limiting factor for colony growth and increasing resource availability, as well as producing a localized cooling effect. Our results show that arid urban ecosystems may include considerable biodiversity, in part thanks to increased landscape heterogeneity resulting from the irrigation of green areas.

Biodiversity conservation in urban parks: a study of ground-dwelling ants (Hymenoptera: Formicidae) in Rio de Janeiro City

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.

Xerothermic Grassland Protection by Means of Sheep Grazing: What is the Short-Term Effect on Ants?

Livestock grazing is a common management practice recommended to protect biodiversity of semi-natural grasslands. However, the effects of specific management regimes on species diversity can differ considerably among taxonomic groups. We studied short-term effects of sheep grazing on species diversity of ants. We investigated whether one season of sheep grazing affects the species richness of ants and causes a compositional change in species occurrence. We conducted our study in southern Poland at five Natura 2000 sites that create favourable habitats for thermo- and xerophilic ants. The average number of ant species detected in grazed plots was slightly but insignificantly higher as compared with that in ungrazed ones. Three species were detected only in ungrazed plots. Our results are in accordance with other reports, leading to the conclusion that the variation in ant diversity may be primarily driven by site-specific conditions rather than grazing per se.

Taxonomic and Functional Ant Diversity Along tropical, Subtropical, and Subalpine Elevational Transects in Southwest China.

Although elevational gradients of biodiversity have long been the topic of scientific research, information on patterns of, and processes that shape insect community structure across elevation is still lacking. Addressing this gap requires the use of both taxonomic and functional approaches when studying diversity across elevational gradients. In this study, we examined taxonomic and functional alpha and beta diversity of ant assemblages sampled along tropical, subtropical, and subalpine elevational transects in Yunnan Province, southwest China. Species richness was used to quantify taxonomic alpha diversity, and two indices (FD and FRic) were calculated using morphological measurements to quantify functional alpha diversity. Taxonomic and functional beta diversity were partitioned into their turnover- and nestedness-resultant components. Though temperature and functional alpha diversity decreased linearly with increasing elevation, taxonomic alpha diversity showed a significant logarithmic decrease, with few species present at elevations greater than 3000 m a.s.l. The turnover-resultant component of taxonomic beta diversity increased with increasing elevational distance, while the nestedness-resultant component of functional beta diversity increased with increasing elevational distance in the subtropical transect. The observed patterns of taxonomic and functional diversity reflected ants’ thermophilic nature, implying functional adaptations (i.e., nested functional diversity) at higher elevations where environmental conditions were unfavorable.

Species-level predation network uncovers high prey specificity in a Neotropical army ant community.

Army ants are among the top arthropod predators and considered keystone species in tropical ecosystems. During daily mass raids with many thousand workers, army ants hunt live prey, likely exerting strong top-down control on prey species. Many tropical sites exhibit a high army ant species diversity (>20 species), suggesting that sympatric species partition the available prey niches. However, whether and to what extent this is achieved has not been intensively studied yet. We therefore conducted a large-scale diet survey of a community of surface-raiding army ants at La Selva Biological Station in Costa Rica. We systematically collected 3,262 prey items from eleven army ant species (genera Eciton, Nomamyrmex and Neivamyrmex). Prey items were classified as ant prey or non-ant prey. The prey nearly exclusively consisted of other ants (98%), and most booty was ant brood (87%). Using morphological characters and DNA barcoding, we identified a total of 1,103 ant prey specimens to the species level. One hundred twenty-nine ant species were detected among the army ant prey, representing about 30% of the known local ant diversity. Using weighted bipartite network analyses, we show that prey specialization in army ants is unexpectedly high and prey niche overlap very small. Besides food niche differentiation, we uncovered a spatiotemporal niche differentiation in army ant raid activity. We discuss competition-driven multidimensional niche differentiation and predator-prey arms races as possible mechanisms underlying prey specialization in army ants. By combining systematic prey sampling with species-level prey identification and network analyses, our integrative approach can guide future research by portraying how predator-prey interactions in complex communities can be reliably studied, even in cases where morphological prey identification is infeasible.

Invertebrate community response to fire and rodent activity in the Mojave and Great Basin Deserts.

Recent increases in the frequency and size of desert wildfires bring into question the impacts of fire on desert invertebrate communities. Furthermore, consumer communities can strongly impact invertebrates through predation and top‐down effects on plant community assembly. We experimentally applied burn and rodent exclusion treatments in a full factorial design at sites in both the Mojave and Great Basin deserts to examine the impact that fire and rodent consumers have on invertebrate communities. Pitfall traps were used to survey invertebrates from April through September 2016 to determine changes in abundance, richness, and diversity of invertebrate communities in response to fire and rodent treatments. Generally speaking, rodent exclusion had very little effect on invertebrate abundance or ant abundance, richness or diversity. The one exception was ant abundance, which was higher in rodent access plots than in rodent exclusion plots in June 2016, but only at the Great Basin site. Fire had little effect on the abundances of invertebrate groups at either desert site, with the exception of a negative effect on flying‐forager abundance at our Great Basin site. However, fire reduced ant species richness and Shannon's diversity at both desert sites. Fire did appear to indirectly affect ant community composition by altering plant community composition. Structural equation models suggest that fire increased invasive plant cover, which negatively impacted ant species richness and Shannon's diversity, a pattern that was consistent at both desert sites. These results suggest that invertebrate communities demonstrate some resilience to fire and invasions but increasing fire and spread of invasive due to invasive grass fire cycles may put increasing pressure on the stability of invertebrate communities.

Epigaeic ant diversity and distribution in the Sandstone Sourveld in KwaZulu‐Natal, South Africa

AbstractAnts are sensitive to habitat change and may be affected by disturbances, such as alien plant invasion. Alien plant invasion is associated with negative effects on the functioning of ecosystems and may have adverse impacts on biodiversity. The aim of this study was to determine the diversity of ground‐dwelling ants in Tanglewood and Giba Gorge Reserves in KwaZulu‐Natal Province, South Africa. Ants were sampled in the wet and dry seasons. Pitfall trap sampling was carried out in an intact grassland, forest and a disturbed grassland. We collected 360 samples resulting in a total of 2,577 occurrences comprising of 54 species. We found that diversity of ants in the two sites was influenced by vegetation type. The intact grassland in the two reserves had greater diversity (40 ± 4.45) of ants compared with forest (22 ± 4.86) and disturbed grassland (27 ± 1.15); however, the disturbed grassland supported higher ant occurrences (50.03 ± 31.6). Opportunists represented the most diverse functional group with 17 species followed by specialist predators with 13 species and generalised Myrmicinae with 10 species. These results suggest that grassland disturbance by alien plant invasion provides suitable environmental conditions that may increase ant occurrences but decrease ant diversity.

Local and regional drivers of ant communities in forest-grassland ecotones in South Brazil: A taxonomic and phylogenetic approach.

Understanding biological community distribution patterns and their drivers across different scales is one of the major goals of community ecology in a rapidly changing world. Considering natural forest-grassland ecotones distributed over the south Brazilian region we investigated how ant communities are assembled locally, i.e. considering different habitats, and regionally, i.e. considering different physiographic regions. We used taxonomic and phylogenetic approaches to investigate diversity patterns and search for environmental/spatial drivers at each scale. We sampled ants using honey and tuna baits in forest and grassland habitats, in ecotones distributed at nine sites in Rio Grande do Sul state, Brazil. Overall, we found 85 ant species belonging to 23 genera and six subfamilies. At the local scale, we found forests and grasslands as equivalent in ant species and evolutionary history diversities, but considerably different in terms of species composition. In forests, the soil surface air temperature predicts foraging ant diversity. In grasslands, while the height of herbaceous vegetation reduces ant diversity, treelet density from forest expansion processes clearly increases it. At a regional scale, we did not find models that sufficiently explained ant taxonomic and phylogenetic diversity based on regional environmental variables. The variance in species composition, but not in evolutionary histories, across physiographic regions is driven by space and historical processes. Our findings unveil important aspects of ant community ecology in natural transition systems, indicating environmental filtering as an important process structuring the communities at the local scale, but mostly spatial processes acting at the regional scale.

Connectivity explains local ant community structure in a Neotropical forest canopy: a large-scale experimental approach.

Understanding how habitat structure and resource availability affect local species distributions is a key goal of community ecology. Where habitats occur as a mosaic, variation in connectivity among patches influences both local species richness and composition, and connectivity is a key conservation concern in fragmented landscapes. Similarly, availability of limiting resources frequently determines species coexistence or exclusion. For primarily cursorial arthropods like ants, gaps between neighboring trees are a significant barrier to movement through the forest canopy. Competition for limited resources such as nest sites also promotes antagonistic interactions. Lianas (woody vines) connect normally isolated neighboring tree crowns and often have hollow stems inhabited by ants. We used two large-scale liana-removal experiments to determine how connectivity and nest site availability provided by lianas affect arboreal ant species richness, species composition, and β-diversity in a lowland tropical forest in Panama. Removing lianas from a tree crown reduced ant species richness up to 35%, and disproportionately affected species that require large foraging areas. Adding artificial connectivity to trees mitigated the effects of liana removal. Ant colonization of artificial nests was higher (73% occupied) in trees without lianas vs. trees with lianas (28% occupied). However, artificial nests typically were colonized by existing polydomous, resident ant species. As a result, nest addition did not affect ant community structure. Collectively, these results indicate that lianas are important to the maintenance of arboreal ant diversity specifically by providing connectivity among neighboring tree crowns. Anticipated increases in liana abundance in this forest could increase the local (tree-level) species richness of arboreal ants, with a compositional bias toward elevating the density of broad-ranging specialist predators.