Morphological prediction of worker size discrimination and relative abundance of sympartic species of Pseudacteon (Dipt., Phoridae) parasitoids of the fire ant, Solenopsis saevissima (Hym., Formicidae) in Brazil

Patterns of attack for collected species of phorids are predicted using multivariate morphometrics of female Pseudacteon species and worker size distributions of parasitized fire ants, Solenopsis saevissima. The model assumes that there is a direct correlation between phorid size and the size range of the worker ant attacked, and presumes that worker sizes are a resource that is divided by sympatric phorid species to minimize joint parasitism. These results suggest that the community of sympatric Pseudacteon species on only one host species coexists by restricting the size of workers attacked, and secondarily by differing diel patterns of ovipositional activity. When we compared relative abundance of species of Pseudacteon with the size distribution of foragers of S. saevissima, our observed distribution did not differ significantly from our predicted relative abundance of females of Pseudacteon. The activity of Pseudacteon may be a factor determining forager size distributions.

Intercontinental Differences in the Abundance of Solenopsis Fire Ants (Hymenoptera: Formicidae): Escape from Natural Enemies?

The absence of natural enemies often allows exotic pests to reach densities that are much higher than normally occur in their native habitats. When Solenopsis fire ants were introduced into the United States, their numerous natural enemies were left behind in South America. To compare intercontinental fire ant densities, we selected 13 areas in South America and another 12 areas in North America. Sample areas were paired with weather stations and distributed across a broad range of climatic conditions. In each area, we measured fire ant densities at 5 preselected roadside sites that were at least 5 km apart. At each site, we also measured foraging activity, checked for polygyne colonies, and recorded various kinds of environmental data. In most areas, we also measured fire ant densities in lawns and grazing land. Fire ant populations along roadsides in North America were 4-7 times higher than fire ant populations in South America. Similar intercontinental differences were found in lawns and on grazing lands. These intercontinental differences in fire ant abundance were not associated with sampling conditions, seasonal variability, habitat differences, or the frequency of polygyny. Although several correlations were found with long-term weather conditions, careful inspection of the data suggests that these correlations were probably more coincidental than causal. Cultural differences in roadside maintenance may explain some of the intercontinental differences in fire ant abundance, but they did not account for equivalent intercontinental differences in grazing land and mowed lawns. Bait tests showed that competition with other ants was much more important in South America; however, we were not able to determine whether this was a major cause of intercontinental differences or largely a consequence of other factors such as the numerous pathogens and parasites that are found in South America. Because this study was correlational, we were unable to determine the cause(s) of the large intercontinental difference in fire ant abundance that we observed. However, we were able to largely exclude a number of possible explanations for the differences, including sampling, season, polygyny, climate, and aspects of habitat. By a process of elimination, escape from natural enemies remains among the most likely explanations for the unusually high densities of fire ants found in North America.

Effect of lithium on behavioral disinhibition induced by electrolytic lesion of the median raphe nucleus

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Aerial line transect survey to estimate abundance of marsh deer (Blastocerus dichotomus) (Illiger, 1815)

A população de cervo-do-pantanal (Blastocerus dichotomus) está drasticamente reduzida no Brasil. O nosso objetivo foi o de estimar a abundância do cervo-do-pantanal na bacia do Rio Paraná e discutir a metodologia aplicada. Os resultados darão suporte para uma análise do impacto do enchimento da represa de Porto Primavera sobre essa população. Sessenta e nove animais foram registrados através de sobrevôo utilizando-se a metodologia de transecção linear com amostragem das distâncias. Os dados não corrigidos resultaram em uma densidade estimada de 0,0035ind/ha e uma população de 636 indivíduos. A correção de g para os animais que não foram vistos apresentou uma densidade de 0,0049 ind/ha e uma abundância de 896 (CV=0,27) indivíduos. A metodologia foi aplicada com sucesso na estimativa de cervo-do-pantanal. Esse resultado é importante para avaliarmos a população do cervo-do-pantanal na área e para futuramente analisarmos o impacto do enchimento da represa.

Abundance of sedentary consumers and sessile organisms along the wave exposure gradient of subtropical rocky shores of the south-west Atlantic

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

Ephemeroptera, Plecoptera and Trichoptera assemblages from riffles in mountain streams of Central Brazil: environmental factors influencing the distribution and abundance of immatures

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

Application of the Potentiometric Stripping Analysis with Constant Current for the Determination of Lithium Ions Using a Spinel-Type Manganese (IV) Oxide-Modified Carbon Paste Electrode

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Electrochemical evaluation of the a carbon-paste electrode modified with spinel manganese(IV) oxide under flow conditions for amperometric determination of lithium

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

Use of lithium niobate detector for measuring X-ray intensity in mammographic range

A detector system that can measure X-ray intensity in the mammographic range of 22 to 36 kVp (equivalent photon energies ofthe beam between 11 and 15 keV) is presented. It consists of a lithium mobate detector and a high-sensitivity current-to-voltage converter.

Messenger ribonucleic acid abundance of intestinal enzymes and transporters in feed-restricted and refed chickens at different ages

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of lithium additive on the microstructure and electrical responses of 0.9PMN-0.1PT ceramics

Structural effects of lithium additive on 0.9PMN-0.1PT powders prepared by Ti-modified columbite route were studied. The substitution of Li+ ions for Mg2+ ions in the B-site sub-lattice of 0.9PMN-0.1PT perovskite structure was explained in terms of lead and oxygen vacancies generation originated as consequence of the ionic compensation of negatively charged Li'(Mg) sites. The rise in mass transport as consequence of the increasing of Pb2+ and O2- vacancies produces more agglomerated particles during the powder synthesis and changes the mechanical characteristics between grain and grain boundary of sintered ceramic. The relation between K-m and T-m values, the difference between ionic radii of B cation and the molar volume were used to explain the changes in the relaxor behavior and diffusiveness of phase transition as function of lithium doping, which are corroborated by the results obtained through the ferroelectric characterization.

Composition and abundance of shrimp species (penaeidea and caridea) in Fortaleza Bay, Ubatuba, São Paulo, Brazil

The abundance and spatio-temporal distribution of the caridean and penaeid fauna from Fortaleza Bay, Ubatuba, São Paulo, Brazil, were analyzed. Seven transects were sampled over a one year period from November 1988 to October 1989. A total of 17047 shrimps were captured, representing 13 species belonging to 5 families. The interaction of temperature and type of sediment was fundamental in determining the presence and abundance of shrimp species in the area.

Annual, seasonal and spatial variation of abundance of the shrimp Artemesia longinaris (Decapoda : Penaeoidea) in south-eastern Brazil

The influence of several environmental factors oil the abundance and spatial-temporal distribution of the shrimp Artemesia longinaris were investigated from January 1998 to December 1999 in the Ubatuba region of São Paulo State, Brazil. Collections were performed monthly in the bays of Ubatumirim (UBM), Ubatuba (UBA) and Mar Virado (MV). Six sampling transects were estabilshed in each bay, four were parallel to the shore line, and two were next to the rocky shores. A commercial shrimp fishing boat equipped with two 'double-rig' nets was used. A total of 11,503 individuals was collected, including 1633 from UBM, 6344 from UBA and 3526 from MV the majority of the captured specimens came from the deeper areas (15 to 20 m) with high salinity (34 to 36 ppt). The highest abundance of A. longinaris in Ubatuba bay was recorded in areas where fine and very fine sand comprised more than 70% of the sediment. Moreover, the abundance of A. longinaris followed a seasonal trend, being higher during the summer, when intrusions of cold South Atlantic Coastal Waters (SACW) are frequent. Thus, type of sediment, temperature and salinity are determinant factors in the distribution of A. longinaris in the studied region.

Temporal variation in the abundance of two species of thrushes in relation to fruiting phenology in the Atlantic rainforest

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

Factors regulating diversity and abundance of fish communities in Pantanal lagoons, Brazil

The factors effecting fish species richness, evenness and relative abundance in 19 floodplain lagoons in the Pantanal (Brazil) were examined. Richness and evenness were strongly correlated with the lagoon's: (i) isolation time from the main river; (ii) depth; and (iii) distance from the main river. Abundance of the five dominant fish species was correlated mainly with: (a) macrophyte cover; (b) the distance from the main river; and (c) piscivore abundance. These results suggest that the species select lagoons to avoid or minimize their confinement in inappropriate floodplain habitats. A combination of strategies, together with variations in the lagoon's connection period, determines the diversity and abundance of the fish species in the Nhecolandia Pantanal.