Energy substrate used by workers of leaf-cutting ants during nest excavation

Energy substrate used by workers of leaf-cutting ants during nest excavation. In this study we aimed to ascertain whether leaf-cutting ant workers lose body reserves (fat or sugars) as a function of nest excavation. For each treatment, we isolated 10 workers of Atta sexdens into two experimental groups, Control (C- without excavation) and Soil (S- with excavation), which were kept for different time intervals (0, 24, 48 or 72 hours), totaling 700 tested workers. We then determined the concentration of soluble carbohydrates and total lipid content in them. The total carbohydrates were determined colorimetrically, based on the reaction between carbohydrates and sulfuric acid-phenol. For determination of lipids, the insects were immersed in organic solvent until they reached a constant weight. Our results showed that carbohydrates are consumed during nest excavation activities. In the experimental groups S24, S48 and S72, there was an average reduction of 5.82 (20.42%), 14.31 (44.96%) and 13.27 (43.96%) µ.mg-1 in soluble sugar when compared with the experimental groups that did not excavate. Furthermore, the lipids were not used during this activity. With respect to dry mass of the workers, their values were C0 = 8%, C24 = 10.4%, C48 = 9.2%, C72 = 10%, S24 = 9.2%, S48 = 8.7% and S72 = 8.5%. Our results show experimentally that the source of energy for nest excavation is carbohydrates, whereas lipids are conserved for other activities.

What is the stimulus for the excavation of fungus chamber in leaf-cutting ants?

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

Micronutrient contents of a revegetated saprolite exposed by excavation of an oxisol

Soils of the Brazilian Cerrado biome have been found to be deficient in copper (Cu) and zinc (Zn). In this area, an Oxisol was deeply excavated in 1962 during the construction of a hydroelectrical plant, and the exposed saprolite material was abandoned, without any reclamation measures. The abandoned land was a harsh environment for plant growth, and the secondary vegetation has not recovered. A field trial was established in 1992 to assess the effects of different grass species and lime amendments on soil reclamation at the degraded site. In 2011 soil samples were collected at three depths (0-10, 10-20, and 20-40cm) from vegetated and bare plots over tilled saprolite, from an untreated area of the saprolite, and from an Oxisol under native forest, used as external reference. Nineteen years after the reclamation effort was begun, the organic carbon (OC) content of the restored saprolite still was much lower than that of the Oxisol under natural vegetation. The undisturbed Oxisol was deficient in extractable Cu (0.16-0.10mgkg(-1)) and Zn (0.10-0.02mgkg(-1)) and exhibited rather low concentrations of extractable iron (Fe; 5.24-1.47mgkg(-1)) and manganese (Mn; 3.21-0.77mgkg(-1)). However, the saprolite under reclamation showed even lower levels of these elements compared to the native forest soil. In the natural soil, OC, N, extractable Fe, Mn, and Cu showed stratification, but this was not the case for extractable Zn. Although the reclaimed saprolite still was far from predisturbance conditions, the revegetation treatments promoted recovery of OC, N, Fe, Mn, and Cu at the surface layers, which resulted in incipient stratification. Extractable Fe, Mn, and Cu were correlated to OC, whereas no association between Zn and OC was detected. Our results also suggest that reclamation of the excavated saprolite may be constrained by micronutrient deficiencies and mostly by the extremely low levels of Zn and Cu.

Distribuição do sistema radicular da goiabeira 'Rica' produzida a partir de estaquia herbácea

O conhecimento da distribuição do sistema radicular de plantas, principalmente de perenes, não é muito estudado, devido a inúmeros fatores, dentre os quais, a dificuldade inerente ao método de amostragem. A presente pesquisa objetivou conhecer o sistema radicular da goiabeira através do método de escavação. Utilizando jatos de água, retirou-se a terra até um volume de 10 m³ (5x5x0,4m), subdivididos em paralelepípedos de 0,1 m³ (0,5x0,5x0,4m), expondo o sistema radical da goiabeira 'Rica'. Verificou-se um vigoroso sistema radicular sem a caracterização da raiz principal e com distribuição homogênea, grande número de raízes primárias, proporcionado pela adequada formação de mudas, através de estaquia herbácea.

Internal Architecture and Population Size of Acromyrmex subterraneus molestans (Hymenoptera, Formicidae) Nests: Comparison Between a Rural and an Urban Area

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Nest Digging by Leaf-Cutting Ants: Effect of Group Size and Functional Structures.

Leaf-cutting ant workers dig underground chambers, for housing their symbiotic fungus, interconnected by a vast quantity of tunnels whose function is to permit the entrance of food (leaves), gaseous exchanges, andmovement of workers, offspring, and the queen. Digging is a task executed by a group of workers, but little is known about the group effect and group-constructed functional structures. Thus, we analyzed the structures formed by worker groups (5, 10, 20, and 40 individuals) of the leaf-cutting ant, Atta sexdens rubropilosa, for 2 days of excavation. The digging arena was the same for the 4 groups, with each group corresponding to a different density. Our results verified a pattern of tunneling by the workers, but no chamber was constructed. The group effect is well known, since the 40-worker group dug significantly more than the groups of 5, 10, and 20. These groups did not differ statistically from each other. Analysis of load/worker verified that workers of the smallest group carried the greatest load. Our paper demonstrates the group effect on the digging of nests, namely, that excavation is proportional to group size, but without emergence of a functional structure such as a chamber.

Lipid and energy contents in the bodies of queens of Atta sexdens rubropilosa Forel (Hymenoptera, Formicidae): pre-and post-nuptial flight

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Clinical and microbiological performance of resin-modified glass-ionomer liners after incomplete dentine caries removal

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

Substrate distribution in fungus chambers in nests of Atta bisphaerica Forel, 1908 (Hym., Formicidae)

Substrate distribution was studied in three adult colonies of the leaf-cutting ant Atta bisphaerica Forel, 1908 using dye. Some supply holes were mapped using baits made from small plastic straws impregnated with citric pulp. Two holes, equidistant from one another, were then selected in each nest. The colonies were excavated completely 24 h after bait placement. During excavation, fungus chambers were checked for dye. We observed that the dyed baits were distributed in all sectors and at all depths regardless of where the baits had been placed. This supported the hypothesis that toxic baits placed in a single supply hole are uniformly distributed throughout the colony.

Tunnelling behaviour of the Asian subterranean termite in heterogeneous soils: presence of cues in the foraging area

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

Monoculture of Leafcutter Ant Gardens

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Métodos e técnicas geoelétricas rasas na delimitação de área afetada por ruptura em teto de túnel urbano

Este trabalho apresenta um uso da geofísica aplicada em uma situação de ambiente urbano. O objetivo dos levantamentos foi o de delimitar a extensão da zona afetada por um colapso e desmoronamento do teto de um túnel em construção sob o Parque do Ibirapuera na capital paulista. São descritos e apresentados os resultados obtidos através do emprego dos métodos geofísicos geoelétricos e suas técnicas, em uma situação emergencial e de risco em uma área urbana na cidade de São Paulo. Também são comparadas as técnicas/arranjos de campo e a forma de apresentação e interpretação dos mesmos. Os métodos empregados foram a Eletrorresistividade, Polarização Induzida (IP) e Potencial Espontâneo (SP). Os trabalhos de campo e interpretação preliminar foram efetuados em apwenas um fim de semana (sábado e domingo). Os resultados mostraram-se plenamente satisfatórios e possibilitaram significativa redução nos custos nas obras de remediação da área do incidente, cuja área decresceu da inicialmente estimada pela engenharia (20x20 m) para 3x5 m definida pelos estudos geofísicos.

O jardim de fungo atua como um molde para a construção das câmaras em formigas cortadeiras?

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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.

Placentation in the capybara (Hydrochaerus hydrochaeris), agouti (Dasyprocta aguti) and paca (Agouti paca)

Placentae of three hystricimorph rodents-capybara, agouti and paca-were examined by conventional histology, immunohistochemistry for cytokeratin and vimentin, and TUNEL staining. The placentae were divided into lobules of labyrinthine syncytium separated by interlobular and marginal trophoblast. The subplacenta comprised cytotrophoblasts, supported on lamellae of allantoic mesoderm, and syncytiotrophoblast. The central excavation was still apparent in the definitive placenta of capybara. In agouti and paca, the decidua of the junctional zone formed a mesoplacenta comprising a capsule and a pedicle. Towards term the pedicle formed a tenuous attachment between placenta and uterine wall comprising a few maternal vessels surrounded by degraded tissue. In paca placenta, it was shown by TUNEL staining that breakdown of this tissue occurred by apoptosis. The visceral yolk sac was highly villous and, in agouti, the yolk sac villi were extremely long. Lateral to its attachment to the placenta, the fetal surface was covered with non-vascular yolk sac endoderm. A layer of spongiotrophoblast cells was interposed between the endoderm and the marginal trophoblast. (C) 2002 Elsevier B.V. Ltd. All rights reserved.