Revisionary notes on the fungus-growing ant genus Mycetarotes Emery (Hymenoptera, Formicidae)

Mycetarotes is a small genus of the exclusively Neotropical fungus-growing ants, that includes M. parallelus (Emery), M. senticosus Kempf, M. acutus Mayhé-Nunes and M. carinatus Mayhé-Nunes. We hereby revise historical and recent information regarding Mycetarotes species for the first time, providing an identification key to workers, diagnoses, synoptic illustrated redescriptions of the species, including those of sexuals when known, updates of distributional records, and nest pictures of M. carinatus and M. parallelus. We comment the taxonomy and phylogenetic relationships among Mycetarotes and related genera, and on their geographical distribution. The available biological information on the genus is summarized.

Morphological studies on castes of Protopolybia chartergoides (Hymenoptera, Vespidae, Epiponini) observed in colonies during male production stage

Social wasps are important for the study of social behavior evolution because their colonies present different degrees of caste differentiation, from morphologically similar to highly conspicuous, associated with the occasional presence of intermediate females, which bears developed ovaries but no insemination. In the Polistinae, depending on the taxon, such differentiation can be discreet or conspicuous. This work intended to study morphological and physiological differences between castes in Protopolybia chartergoides by using morphometric analyses associated with multivariate statistical analyses and physiological evaluations from females' ovarian development. Results evidence low morphological and physiological differences among the castes in P. chartergoides, indicating three groups of females: queens, workers and intermediates. In this way, it was possible to suggest that Protopolybia chartergoides presents post-imaginal caste differentiation (or a very subtle form of pre-imaginal determination).

A 15-year post evaluation of the fire effects on ant community in an area of Amazonian forest

Fire represents an important disturbance to ant communities in areas of fire regime. Otherwise, little is known about the effects of fire on ant communities in areas of non-fire regimes, such as in the Amazonian region. We evaluated the long-term effect of fire on ant species richness in a rain forest (Bacaba Plateau) burned 15-years ago and compare our data with the data of primary unburned forest. A total of 85 ant species distributed in 21 genera and 14 tribes were collected; among them, 72 and 44 species were found on the litter and vegetation, respectively. The fire damaged forest studied supports an intermediate richness of ants when compared to a primary unburned rain forest in the same region. A comparative analysis of ant species richness showed that the Bacaba Plateau presented a different ant fauna when compared with the primary unburned forests, suggesting that fire can alter ant species composition. Although, our results cannot be conclusive on the effects of fire on ant community, they represent a pioneer data on human induced fire in tropical rain forests.

A new species of the fungus-farming ant genus Mycetagroicus Brandão & Mayhé-Nunes (Hymenoptera, Formicidae, Attini)

The fungus-farming ant genus Mycetagroicus Brandão & Mayhé-Nunes was proposed based on three species from the Brazilian "Cerrado": M. cerradensis, M. triangularis and M. urbanus. Here we describe a new species of Attini ant of the genus Mycetagroicus, M. inflatus n. sp., based on two workers collected in eastern Pará State, Brazil. A new key for species identification, comments on differences among species and new geographical distribution data are furnished.

Rediscovery of the putatively extinct ant species Simopelta minima (Brandão) (Hymenoptera, Formicidae), with a discussion on rarity and conservation status of ant species

Simopelta minima (Brandão, 1989) was originally described based on four workers collected in soil samples from a small cocoa plantation in Ilhéus, state of Bahia, northeastern Brazil. In the subsequent years after the description, this cocoa plantation was eliminated and the species was then considered extinct by the Brazilian environmental institutions. The recent rediscovery of S. minima workers in subterranean pitfall trap samples from Viçosa, state of Minas Gerais, southeastern Brazil, over 1.000 km distant from type locality, suggests that the rarity and vulnerability status of some ant species may be explained by insufficient sampling of adequate microhabitats, in time and space.

More than one inseminated female in colonies of the independent-founding wasp Mischocyttarus cassununga von Ihering (Hymenoptera, Vespidae)

In the primitively eusocial wasps, especially Polistini and Mischocyttarini tribes, the physiological condition of each individual is strongly associated with its dominance status in the colonial hierarchy. As a rule, in independent-founding wasps, female wasps are all morphologically alike, and their role is apparently quite flexible even as adults. However, some studies have shown that differences in body size can exist between reproductive and non-reproductive females. Thus, the present study aimed at detecting differences between reproductive (inseminated) and non-reproductive (uninseminated) individuals based on morphological and physiological parameters. We tape-recorded the daily behavioural repertory of six colonies of Mischocyttarus cassununga for determining the hierarchical dominance in the field, and then collected these colonies (in different cycle stages) for measuring 13 set characters, and assessing the physiological condition of each individual by inspecting their fat bodies and ovaries. Our results revealed that inseminated and uninseminated females are not significantly different in relation to body size, in spite of first group shows higher average than second in almost all measured parts. The physiological evaluation of each individual demonstrated more than one inseminated female per colony during all stages of the colony cycle, suggesting a strategic condition of this species against difficulties (predation and parasitism of the colony) in nature.

Seasonal flight and resource collection patterns of colonies of the stingless bee Melipona bicolor schencki Gribodo (Apidae, Meliponini) in an Araucaria forest area in southern Brazil

Melipona bicolor schencki occurs in southern Brazil and at high elevations in southeastern Brazil. It has potential for use in meliponiculture but this stingless bee species is vulnerable to extinction and we have little knowledge about its ecology. In order to gather essential information for species conservation and management, we made a study of seasonal flight activities in its natural environment. We sampled bees entering the nests with pollen, nectar/water and resin/mud, in five colonies during each season. In parallel, we analyzed the influence of hour of the day and meteorological factors on flight activity. Flights were most intense during spring and summer, with daily mean estimates of 2,100 and 2,333 flights respectively, while in fall and winter the daily flight estimate was reduced to 612 and 1,104 flights, respectively. Nectar and water were the most frequently-collected resources, followed by pollen and building materials. This preference occurred in all seasons, but with variations in intensity. During spring, daily flight activity lasted over 14 hours; this period was reduced in the other seasons, reaching eight hours in winter. Meteorological factors were associated with 40.2% of the variation in flight and resource collection activity. Apparently, other factors that we did not measure, such as colony needs and availability of floral resources, also strongly influence the intensity of resource collection.

Epigean ant communities in Atlantic Forest remnants of São Paulo: a comparative study using the guild concept

Epigean ant communities in Atlantic Forest remnants of São Paulo: a comparative study using the guild concept. The guilds constitute a valuable ecological tool, because they allow conducting comparisons among environments under different conditions. The ants can be used as ecological indicators, mainly for the monitoring of degraded forest areas. The aim of this research was to study guild organization among the epigeous Formicidae living in Atlantic forest remnants of the State of São Paulo, Brazil. Ant collections were performed in three distinct Atlantic forest biome areas: arboreal littoral vegetation ("restinga") (Cananéia), semideciduous seasonal forest (Piracicaba) and dense ombrophylousforest (Pariquera-Açu). After identification, the ants were grouped into guilds, based on the ecological attributes of behavior and habit, according to the literature. Nine guilds were found; the semideciduous seasonal forest ecosystem presented eight of them, followed by the arboreal sandbank (7) and dense ombrophylous forest (6). The guilds found were: litter omnivorous and scavengers, granivorous species, specialist predators living in litter and soil, litter generalist predators, subterranean mealybug-dependent species, army ants, dominant or subdominants arboreal, that occasionally forage on the ground, soil or litter dominant and fungus-growers, using feces and insect body fragments. The guilds found can be used in the monitoring of the mirmecofauna in the Atlantic Forest biome, supplying insights for further ecological studies.

Updated list of ant species (Hymenoptera, Formicidae) recorded in Santa Catarina State, southern Brazil, with a discussion of research advances and priorities

Updated list of ant species (Hymenoptera, Formicidae) recorded in Santa Catarina State, southern Brazil, with a discussion of research advances and priorities. A first working list of ant species registered in Santa Catarina State, southern Brazil was published recently. Since then, many studies with ants have been conducted in the state. With data compiled from published studies and collections in various regions of the state, we present here an updated list of 366 species (and 17 subspecies) in 70 ant genera in Santa Catarina, along with their geographical distribution in the seven state mesoregions. Two hundred and seven species are recorded in the Oeste mesoregion, followed by Vale do Itajaí (175), Grande Florianópolis (150), Norte (60), Sul (41), Meio Oeste (23) and Planalto Serrano (12). The increase in the number of records since 1999 results from the use of recently adopted sampling methods and techniques in regions and ecosystems poorly known before, and from the availability of new tools for the identification of ants. Our study highlights the Meio Oeste, Planalto Serrano, Sul and Norte mesoregions, as well as the deciduous forest, mangrove, grassland and coastal sand dune ecosystems as priority study areas in order to attain a more complete knowledge of the ant fauna in Santa Catarina State.

Emigration of a colony of the leaf-cutting ant Acromyrmex heyeri Forel (Hymenoptera, Formicidae)

Emigration of a colony of the leaf-cutting ant Acromyrmex heyeri Forel (Hymenoptera, Formicidae). Colony migration is a poorly studied phenomenon in leaf-cutting ants. Here we report on the emigration of a colony of the leaf-cutting ant A. heyeri in Brazil. The colony emigrated to a new location 47.4 m away from the original nest site, possibly because it had undergone considerable stress due to competitive interactions with a colony of Acromyrmex crassispinus.

Temporal variation in the composition of ant assemblages (Hymenoptera, Formicidae) on trees in the Pantanal floodplain, Mato Grosso do Sul, Brazil

Temporal variation in the composition of ant assemblages (Hymenoptera, Formicidae) on trees in the Pantanal floodplain, Mato Grosso do Sul, Brazil. In this paper we investigate how seasonal flooding influences the composition of assemblages of ants foraging on trees in the Pantanal of Mato Grosso do Sul. During the flood in the Pantanal, a large area is covered by floods that are the main forces that regulate the pattern of diversity in these areas. However, the effects of such natural disturbances in the ant communities are poorly known. In this sense, the objective of this study was to evaluate the effect of temporal variation in assemblages of ants foraging on trees in the Pantanal of Miranda. Samples were collected during a year in two adjacent areas, one who suffered flooding during the wet period and another that did not suffer flooding throughout the year. In 10 sites for each evaluated habitat, five pitfall traps were installed at random in trees 25 m apart from each other. In the habitat with flooding, the highest richness was observed during the flooding period, while there was no significant change in richness in the area that does not suffer flooding. The diversity of species between the two evaluated habitats varied significantly during the two seasons. Most ants sampled belong to species that forage and nest in soil. This suggests that during the flood in flooded habitats, ants that did not migrate to higher areas without flooding adopt the strategy to search for resources in the tree canopy.

Ant species (Hymenoptera, Formicidae) from the seasonally dry tropical forest of northeastern Brazil: a compilation from field surveys in Bahia and literature records

Ant species (Hymenoptera, Formicidae) from the seasonally dry tropical forest of northeastern Brazil: a compilation from field surveys in Bahia and literature records. The Caatingas occur predominantly in northeastern Brazil and comparatively it is the biome that received less attention than any other ecosystem in Brazil, representing the region where invertebrate groups are less known. We present here the first list of ant species of the Caatingas, compiling information from the literature, from a study of samples preserved in alcohol in the Laboratory of Entomology (Universidade Estadual de Feira de Santana), and from a field survey conducted in Milagres, Bahia, submitting standardized 1-m² samples of the leaf-litter to Winkler extractors. Summing all information, 11 subfamilies, 61 genera and 173 species (plus one subspecies) of ants are recognized in the biome. This species number does not consider morphospecies that could not be named due to the lack of reliable recent taxonomic information for some Neotropical ant genera. The list presented here for ant species of the Caatingas is therefore underestimated, but it is relevant because it allows the identification of areas to be sampled in order to improve our knowledge of the diversity of ants in this biome.

Parasitoids of the endangered leafcutter ant Atta robusta Borgmeier in urban and natural areas

Parasitoids of the endangered leafcutter ant Atta robusta Borgmeier in urban and natural areas. Hosts of parasitoids in urban areas may suffer from a double threat of habitat destruction by urbanization and parasitism pressure. Moreover, the parasitoids themselves might be at risk if they are specialists. Here, we studied whether Atta robusta (Hymenoptera, Formicidae), which is on the red list of Brazilian threatened species, suffers from higher parasitism pressure in an urban area compared to a natural one. In addition, we determined whether their specialist parasitoids, Eibesfeldtphora breviloba and Myrmosicarius exrobusta (Diptera, Phoridae), are in risk and evaluated whether they are influenced by habitat structure, temperature, humidity, ant traffic, and time of the day. The study was carried out in an urban park and in a natural protected area in the city of Rio de Janeiro. In each site we chose an open area and a closed area (forest) and sampled nine nests in each area. We found that parasitism pressure was similar in urban and natural areas, with the same two parasitoid species present in both areas. The main difference was related to habitat structure, since M. exrobusta was mainly present in open areas while E. breviloba was almost exclusively found in closed areas. Myrmosicarius exrobusta was not present during the hottest midday times, and its abundance was negatively correlated to vapor pressure deficit. These results suggest that green areas can be an important component in efforts to conserve diversity in urban areas. However, the complexity of the habitats in those areas is a fundamental issue in designing urban parks.

Energetic cost of digging behavior in workers of the leaf-cutting ant Atta sexdens (Fabricius)

Energetic cost of digging behavior in workers of the leaf-cutting ant Atta sexdens (Fabricius). During nest excavation, leaf-cutting ant workers undergo reduction in their body reserve, particularly carbohydrates. In order to estimate the energetic cost of digging, groups of 30 workers of the leaf-cutting ant Atta sexdens were sealed in a hermetic chamber for 24, 48 and 72 hours, with and without soil for digging, and had the CO2 concentration measured using respirometric chambers as well as volume of soil excavated (g). As expected, the worker groups that carried out soil excavation expelled more carbon dioxide than the groups that did not excavate. Therefore, a worker with body mass of 9.65 ± 1.50 mg dug in average 0.85 ± 0.27 g of soil for 24 hours, consuming ca. 0.58 ± 0.23 J. In this study, we calculate that the energetic cost of excavation per worker per day in the experimental set-up was ca. 0.58 J.

Exon-primed intron-crossing (EPIC) markers as a tool for ant phylogeography

Exon-primed intron-crossing (EPIC) markers as a tool for ant phylogeography. Due to their local abundance, diversity of adaptations and worldwide distribution, ants are a classic example of adaptive radiation. Despite this evolutionary and ecological importance, phylogeographical studies on ants have relied largely on mitochondrial markers. In this study we design and test exon-primed intron-crossing (EPIC) markers, which can be widely used to uncover ant intraspecific variation. Candidate markers were obtained through screening the available ant genomes for unlinked conserved exonic regions interspersed with introns. A subset of 15 markers was tested in vitro and showed successful amplification in several phylogenetically distant ant species. These markers represent an important step forward in ant phylogeography and population genetics, allowing for more extensive characterization of variation in ant nuclear DNA without the need to develop species-specific markers.