Phoretic dispersal on bumblebees by bromeliad flower mites (Mesostigmata, Melicharidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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.

NEST REUSE AND COMMUNAL NESTING IN MICROTHURGE-CORUMBAE (HYMENOPTERA, MEGACHILIDAE), WITH SPECIAL REFERENCE TO NEST DEFENSE

Observations on the nesting activities of Microthurge corumbae, carried out at the University Campus of Ribeirao Preto, São Paulo, Brazil, from 1977 to 1981, indicated that 61.9% of nests were re-used by succeeding generations. Re-use by one generation was more frequent than by two generations, and re-use by a third was observed only once. Nests were re-used by one or several females. Single females were more frequently in the first re-use. In these cases nest re-use did not differ essentially from the solitary foundation of a new nest, except for the adoption of a pre-existing nest without excavation. In multifemale nests, analysis of relative age (wing wear), ovarian and spermathecal conditions of associated females and the content of nests at excavation indicated that the social pattern in such colonies is communal. There is some evidence that the associated females are relatives. The chalcidoid wasp Leucospis was the principal nest parasite, and ants of the genus Crematogaster were nest predators. In multifemale nests, the rate of parasitism was significantly lower than in solitary nests, indicating that nest-sharing resulted in improved nest defense. on the other hand. The absence of predation on immatures of the first generation of M. corumbue in multifemale nests suggests that such nests are also more resistant to attack by predators.

THAUMATOMYRMEX STRIPS MILLIPEDES FOR PREY - A NOVEL PREDATORY BEHAVIOR IN ANTS, AND THE 1ST CASE OF SYMPATRY IN THE GENUS (HYMENOPTERA, FORMICIDAE)

We describe, for the first time, the predatory behaviour of Thaumatomyrmex ants on millipedes of the family Polyxenidae, based on field observations of T. atrox and a field and laboratory study of T. contumax. The capture of the prey and the removal process of its body-covering setae by the ants before they eat the millipede are described. This specialized behaviour in at least two species of the genus, belonging to two distinct groups of species, indicates a general trend in Thaumatomyrmex. We coupled this study with a comparative morphological analysis of the mouthparts and digestive tube of these and other Thaumatomyrmex species. Also, we report the first case of sympatry in the genus, which suggests that Thaumatomyrmex includes several species. and not only one highly variable taxon, as hypothesized earlier.

THE LEG EXOCRINE SYSTEM IN SERRITERMES-SERRIFER (HAGEN, 1858), PHYLOGENETIC IMPLICATIONS (ISOPTERA, SERRITERMITIDAE

The leg exocrine gland was examined in two species of Neotropical termites. Scanning microscopy studies showed a set of pores on the ventral surface of the first and second tarsomeres in all legs of Serritermes serrifer. In Heterotermes tenuis these pores are present on a sunken plate in all castes. To date, this gland has been observed only in Rhinotermitid species. The presence of leg exocrine gland provides additional evidence supporting a close phylogenetic relationship between the Serritermitidae and Rhinotermitidae.

PATTERNS OF COLONIZATION AND INCIPIENT NEST SURVIVAL IN ACROMYRMEX-NIGER AND ACROMYRMEX-BALZANI (HYMENOPTERA, FORMICIDAE)

Patterns of colonization by queens and incipient nest survival of the leaf-cutting ants Acromyrmex niger and Acromyrmex balzani were studied by means of belt transects and individually marked incipient nests. No relation was found between colony density and the number of colonization attempts. Both species are not claustral, and high rates of queen mortality were attributed to conspecific executions and predation. of other discernable mortality factors, failure of fungal garden establishment was the most important. Only 34 of 296 A. balzani and 13 of 154 A. niger marked colonies were alive at the end of one year. These figures are higher than those reported for species of Atta. These results are contrasted with those of claustral-founding Atta species. Small colonies are occasionally raided by larger colonies which robbed brood.

Electrophoretical studies of proteins of the hypopharyngeal glands and of the larval food of Melipona quadrifasciata anthidioides Lep (Hymenoptera, Meliponinae)

The electrophoretical protein patterns of hypopharyngeal glands, larval food of Melipona, and royal jelly of Apis were compared.Since protein patterns of hypopharyngeal glands from newly emerged workers, brood cell provisioners and foragers are similar to freshly deposited larval food, the identical protein bands probably represent actual gland secretion. This suggests that, as in Apis, the glands secrete proteins to the larval food, and maintain this ability throughout life, although at slightly different intensities, according to the activity of the bees.The similarity on the electrophoretic profiles of the major larval food protein in Apis and Melipona is an interesting finding because of its probable evolutionary significance.

HERBIVORY AND ASSEMBLAGE STRUCTURE OF MYRMECOPHYTOUS UNDERSTORY PLANTS AND THEIR ASSOCIATED ANTS IN THE CENTRAL AMAZON

The species combinations of myrmecophytic plants were compared in three different, neighboring local central Amazon forest sites. The proportional contribution of myrmecophytes in each setting varied significantly, with Maieta guainensis being the most abundant in each locality. This pattern resulted in low site similarity values. Other recorded species were Hirtella physophora, Tachigalia myrmecophila, Duroia sp., Tococa sp., and Cordia nodosa. Little variability was found with respect to associated ants that inhabited the myrmecophytes, and mutual entropies indicated a high degree of mutualistic interactions. However, for the majority of myrmecophytes, no differences in herbivore damage levels could be attributed to the presence of ants, with only M. guianensis and T. myrmecophila demonstrating significantly lower damages when inhabited by ants. Their respective ant associates, Pheidole minitula and Pseudomyrmex concolor, were thus the only plant-ants with a demonstrable ability to reduce the levels of herbivory in their host plant.

Ventilation of the giant nests of Atta leaf-cutting ants: does underground circulating air enter the fungus chambers?

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

Coordination of construction behavior in the termite Procornitermes araujoi: structure is a stronger stimulus than volatile marking

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Comparative study of resistance to heat in two species of leaf-cutting ants

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Acromyrmex charruanus: a new inquiline social parasite species of leaf-cutting ants

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)