Analysis of Ant Communities Comparing Two Methods for Sampling Ants in an Urban Park in the City of São Paulo, Brazil

This study aimed to analyze the species composition and functional groups of the ant community and to assess the efficiency of two sampling methods, pitfall and leaf litter sampling, in an urban park. A total of 1,401 ants were collected, which belonged to six subfamilies and 36 species. The predominant species was Wasmannia auropunctata (present in 45.36% of the samples), while the functional group of opportunistic ants were the most frequent (present in 83.75% of the samples) and abundant (95.29% of the total collected specimens) functional group. The Jaccard Similarity Index showed a low similarity between the two sampling methods, as the difference of the number of individuals for each species between these two methods was not significant in only one case (Linepithema sp. 1, p = 0.4561). The fungus-growing and cryptic ants were more collected in leaflitter samples (p<0.0001; p = 0.0348 respectively). Although there was no significant difference (p = 0.6397) between the two sampling methods for the total individuals of opportunistic ants, more species of this group were collected in pitfall traps. This difference was not significant because of the high presence of W. auropunctata, an opportunistic ant, in samples of leaf litter. Due to the predominance of tramp ants in the studied area, this article illustrates the importance of green urban areas in ant control strategies, since these sites could be used as a source of new colonization for these ants. Furthermore, the combination of the two sampling methods seems to be complementary for obtaining a more complete picture of the ant community.

Nest architecture and population dynamics of the Ponerinae ant, Ectatomma opaciventre Roger (Hymenoptera : Formicidae)

Eleven nests of Ectatomma opaciventre were collected from January to December, 1994, in Rio Claro, SP, southeastern Brazil. This species excavates their nests up to 68 cm deep, containing 3, 4 or 5 chambers. The hole of entrance has a chimney-like rigid structure, with up to 2/5 cm high. The most numerous colonies were found in January and February, with 47 and 62 adult ants, respectively. The quantity of individuals decreased from March, being observed colonies with only 9 adult ants in June and July. The colony population increased again since September. Reproductive forms (winged ants) were observed between October and February. We did not observed immature stages in July, but they were numerous between September and March. There was a significant correlation between the number of colony individuals and temperature, but not between the number of colony individuals and relative humidity and rainfall. E. opaciventre is a species of hunter ants which have not an efficient recruitment system for food collecting, consequently their colonies are small due to the scarcity of food resources during the colder and dry months.

Nest defense behavior against ant attacks in post-emergent colonies of wasp Mischocyttarus cerberus (Hymenoptera, Vespidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Revision of the Neotropical ant subfamily Leptanilloidinae

The rare Neotropical ant subfamily Leptanilloidinae is revised and its internal phylogeny and biogeography discussed. A new genus, Asphinctanilloides gen.n., including three new species, A, amazona, A. anae and A. manauara, and three new species of Leptanilloides, L. improvisa, L. legionaria and L. sculpturata are described. The only previously known species of the subfamily, L. biconstricta Mann (1923), is redescribed, and the larva of L, legionaria sp.n, is described. Keys to the genera and the species, and a phylogeny of the group are provided. Emphasis has been placed on the study of abdominal and sting characters.

Predaceous ant fauna in new sugarcane fields in the state of São Paulo, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Manipulation of fire ant density, Solenopsis spp., for short-term reduction of Diatraea saccharalis larval densities in Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Nest architecture of the leaf-cutting ant Acromyrmex rugosus rugosus

The prominent nests mounds of many ant species are one of the most obvious signs of their presence, yet the subterranean architecture of nests is often poorly known. The present work aimed to establish the external and internal structure of nests of a species of leaf-cutting ant, Acromyrmex rugosus rugosus, by either marking the interior of nests with talcum powder, or forming casts with cement. Twelve nests were excavated and surveyed, with eight being marked with talcum powder and four cast with cement. The external and internal structure of the nests was highly variable. The largest and smallest nests had mound areas of 9.89 m(2) and 0.01 m(2) respectively. The number of chambers found ranged from I to 26, with maximum dimensions of between 6 and 70 cm. Chambers were found close to the soil surface (6 cm) down to a maximum depth of 3.75 m. In addition to chambers containing fungus garden, some chambers were found to be empty, filled with soil or filled with waste, the first time this has been recorded in a species of Acromyrmex. The nests of A. rugosus rugosus appear to be unusually complex for the genus, containing a diversity of irregular chambers and tunnels.

RAPD analysis of the sexual state and sterile mycelium of the fungus cultivated by the leaf-cutting ant Acromyrmex hispidus fallax

That the symbiotic fungus of leaf-cutting ants only occasionally produces the sexual phase makes their identification confusing. This has occurred so rarely, either in laboratory nests, or in unbalanced field nests. that the possibility of contamination of the fungal garden by other fungi cannot be disregarded. In this paper we describe the formation of several basidiomata in a healthy and free-living nest of the leaf-cutting ant Acromyrmex hispidus fallax. The cultivation in vitro of the sterile mycelia (isolated from the fungal garden) with their typical inflated tips, and the similarity of both forms confirmed by RAPD analysis of their genomic DNA. The fungus was identified as Leucoagaricus gongylophorus.

Functional ultrastructure of the midgut of the fire ant Solenopsis saevissima Forel 1904 (Formicidae : Myrmicinae)

Solenopsis saevissima has a midgut composed of columnar, regenerative, and goblet cells. The midgut epithelium was covered by a basal lamina. Outside the basal lamina, layers of inner oblique, circular, and outer longitudinal muscles were present. Columnar cells showed a basal plasma membrane containing numerous folds, mitochondria, and the nucleus. Rough endoplasmic reticulum, Golgi bodies, membrane bounded vacuoles, and spherocrystals were found in this region. The apical plasma membrane was constituted by microvilli, which were above a region rich in mitochondria. Regenerative cells were found in groups lying by the basal lamina. Goblet cells were associated with an ion-transporting mechanism between the haemolymph and the midgut epithelium. These cells were lying by the midgut lumen and large microvilli were evident, but the cytoplasmic features were similar to the columnar cells.

SEASONAL SPACE USAGE BY THE INTRODUCED PHARAOHS ANT, MONOMORIUM-PHARAONIS (L) (HYM, FORMICIDAE), IN INSTITUTIONAL SETTINGS IN BRAZIL AND ITS RELATION TO OTHER STRUCTURAL ANT SPECIES

In an institutional setting in Brazil, the pharaoh's ant, Monomorium pharaonis was found to be the dominant and most abundant ant present throughout the year. The only other regularly collected ant was the exotic Tapinoma melanocephalum. However, M. pharaonis dominated bait station visitations, although locally concentrated, with other species restricted to regions in which M. pharaonis was not found.

LARVAL INSTARS AND IMMATURE DEVELOPMENT OF A BRAZILIAN POPULATION OF PHARAOHS ANT, MONOMORIUM-PHARAONIS (L) (HYM, FORMICIDAE)

The immature development of pharaoh's ant, Monomorium pharaonis, workers was s died in a naturally collected Brazilian population. Three larval instars were confirmed by measuring maximal cephalic widths in cohorts of known age. Minimum egg to adult duration was 25 days, while the maximum duration was 54 days, both of which are larger than those reported for European populations. Larval instar development is cyclical at the colony level, suggesting reproductive bursts followed by lower reproductive activity of the queens.

Age polyethism in the leaf-cutting ant Acromyrmex subterraneus brunneus Forel, 1911 (Hym., Formicidae)

This study describes and quantifies the behavioural acts of two laboratory colonies of Acromyrmex subterraneus brunneus by investigating worker age polyethism. Twenty-nine behavioural acts were recorded during the 19-week observation period. Young individuals performed tasks inside the nest related to brood care and care for the fungus garden, whereas older individuals performed activities outside the nest such as foraging and activities in the waste chamber. The average longevity (+/- SD) was 108.21 +/- 3.30, 109.15 +/- 1.92 and 122.71 +/- 1.55 days for large, medium and small workers, respectively. The small-sized workers presented a higher probability of reaching older age than large- and medium-sized workers. This study describes task switching according to age polyethism and the relationship of physical and temporal subcastes.

THE POPULATION STATUS OF THE ENDANGERED BRAZILIAN ENDEMIC LEAF-CUTTING ANT ATTA-ROBUSTA (HYMENOPTERA, FORMICIDAE)

The population status of the endemic leaf-cutting ant Atta robusta was assessed using extensive field surveys. In the coastal plain of the state of Rio de Janeiro, we found localized populations of A. robusta, bur no evidence of population recruitment. In disturbed habitats, A. robusta is apparently being displaced by Atta sexdens rubropilosa.

SOLENOPSIS (HYMENOPTERA, FORMICIDAE) FIRE ANT REACTIONS TO ATTACKS OF PSEUDACTERON FLIES (DIPTERA, PHORIDAE) IN SOUTHEASTERN BRAZIL

We studied the responses of Solenopsis fire ants to Pseudacteon phorid fly attacks in southeastern Brazil. The presence of these phorid parasites triggered a suite of phorid-specific defense responses including reduced foraging, bait guarding, a curled defensive posture, and general colony immobility. The existence of these phorid-specific defenses indicates that Pseudacteon phorids exert substantial evolutionary pressure on South American fire ant populations.

Yeasts associated with nests of the leaf-cutting ant Atta sexdens rubropilosa Forel, 1908

A total of 137 yeasts associated with the leaf-cutting ant Atta sexdens rubropilosa Forel, 1908 were characterized, being selected 93 for analysis. Twenty four species belonging to seven genera(Candida, Cryptococcus, Rhodotorula, Sporobolomyces, Tremella, Trichosporon, Pichia) were isolated from the different analysed material. The genus Candida was widely distributed, with C. homilentoma, C. colliculosa-like, C. famata and C. colliculosa being the most prevalent. A few isolates did not fit the standard descriptions and probably some of them could be new biotypes or even new species. Three strains of black yeasts were also isolated, and four others were identified as being Candida spp. The effective number of yeast species was higher in newer sponge. The origin, distribution and relative importance of these microorganisms for the ants are discussed.