Terrestrial isopod diversity in the subtropical neotropics: Itapuã State Park, southern Brazil

We analysed species abundance and composition during one year of sampling at Itapuã State Park, a conservation unit in the State of Rio Grande do Sul, southern Brazil. Samples were collected monthly from May 2003 to April 2004 along a 4 km forest trail divided in three transects along the slopes of a small hill. Terrestrial isopods were hand searched by three people for 40 minutes at two sampling sites along each transect, summing 240 minutes of sampling effort per transect per month. Six species distributed in six families were found. The collector curve stabilised when half the samples were taken, demonstrating sampling sufficiency: analytical estimates did not predict more species to be found in the trail. Atlantoscia floridana (van Name, 1940) was dominant in all transects. Abundance varied along the year with a summer and a winter peak, but peaks were not consistent among transects. The first part of the trail, used for ecotourism, was less diverse, had less species (4 as compared to 6 in the other transects), and was thus also less similar in composition.

Climate and nest opening orientation in Furnarius rufus (Furnariidae)

The Rufous Hornero (Furnarius rufus) is one of the most common bird species in Brazil. Anecdotal information indicates that nest opening orientation in this species is contrary to wind or rainfall direction. To check for the existence of such a pattern, F. rufus nests were randomly sampled within an urban area in central Brazil to assess whether factors such as wind and vegetation cover influence nest opening orientation. Using circular statistics, no evidence was found that nest-opening orientation was important for the species. These results refuse the expected pattern for tree hollow or enclosed nests. The results suggest that factors such as nesting architecture, nest material, nest microclimate or a combination of these, instead of local climate, must be conditioning nesting behavior in this species.

Spatio-temporal variation of the pink shrimp Farfantepenaeus paulensis (Crustacea, Decapoda, Penaeidae) associated to the seasonal overture of the sandbar in a subtropical lagoon

On the southern Brazilian coast, the penaeid pink shrimp Farfantepenaeus paulensis (Pérez-Farfante, 1967) is intensively captured by both artisanal and industrial fisheries. In the Ibiraquera Lagoon, artisanal fishing of juvenile stocks has declined sharply over the last 15 years. The traditional management methods used by fishermen are no longer sustainable due to conflicts with the demands of tourism and weak environmental and public agencies. The dynamics of the timing of the artificial opening and natural reformation of a sandbar across the mouth of the lagoon are regarded as a central socio-ecological problem. We evaluated the abundance and biomass variation of F. paulensis throughout the year and along a spatial gradient measured from the sandbar into the lagoon. We also explored the influence of opening the sandbar on the shrimp population. Samples were collected monthly from February 2004 to February 2005, using a 27 mm mesh cast net, in four different areas, with three sites being sampled per area. Small numbers of large shrimps were captured in the upper area, while greater biomass and abundance of small shrimps were observed near the sandbar, suggesting the role of the inner area as a refuge for growing. The highest records for biomass and abundance were recorded during warm months, regardless if the lagoon was open or closed by the sandbar. The Ibiraquera Lagoon could be more productive for fishermen if the sandbar opening was coincident to the period of natural post-larvae influx. Furthermore, coastal stocks could be improved by opening the sandbar again during summer in conjunction with fishing quotas.

Can climate shape flight activity patterns of Plebeia remota Hymenoptera, Apidae)?

Flight activity of foragers of four colonies of Plebeia remota (Holmberg, 1903) was registered from December 1998 to December 1999, using an automated system (photocells and PLC system). The colonies originated from two different regions: Cunha, state of São Paulo, and Prudentópolis, state of Paraná, Brazil. Flight activity was influenced by different climatic factors in each season. In the summer, the intensity of the correlations between flight activity and climatic factors was smaller than in the other seasons. During the autumn and winter, solar radiation was the factor that most influenced flight activity, while in the spring, this activity was influenced mainly by temperature. Except in the summer, the various climatic factors similarly influenced flight activity of all of the colonies. Flight activity was not affected by geographic origin of the colonies. Information concerning seasonal differences in flight activity of P. remota will be useful for prediction of geographic distribution scenarios under climatic changes.

Effects of anthropogenic impacts on benthic macroinvertebrates assemblages in subtropical mountain streams

The nature of the riparian and surrounding landscape has been modified by anthropogenic activities, which may subsequently alter the composition and functional structure of macroinvertebrate assemblages. The effect of these changes on function of benthic fauna is difficult to assess due to the scarce knowledge on functional structures in tropical streams. In this study we evaluate whether sites impacted and unimpacted by anthropogenic alterations differed in assemblage composition and density, richness and diversity of each functional feeding group. The selection of the sites was related to their distinct riparian characteristics, following the QBRy riparian quality index. Collector-gatherer was the dominant functional feeding group, comprising 91% of total density, whereas the proportion of shredders was very low, representing less of 0.5% of total density. Asemblage composition of macroinvertebrates differed between impacted and unimpacted sites. Predators were dominant in taxa number, representing about 60% of total taxa richness. In addition, the diversity and richness of collector-gatherers differed significantly between degraded and unimpacted sites, reflecting the sensitivity of this group to environmental changes and the utility to be used in the assessment of anthropogenic modifications. The results of this study reinforce the idea that riparian corridor management is critical for the distribution of macroinvertebrate assemblages as well as functional organization of lotic streams.

Climate and land-use changes effects on the distribution of a regional endemism: Melanophryniscus sanmartini (Amphibia, Bufonidae)

ABSTRACT Amphibians are the most threatened vertebrate group according to the IUCN. Land-use and land cover change (LULCC) and climate change (CC) are two of the main factors related to declining amphibian populations. Given the vulnerability of threatened and rare species, the study of their response to these impacts is a conservation priority. The aim of this work was to analyze the combined impact of LULCC and CC on the regionally endemic species Melanophryniscus sanmartini Klappenbach, 1968. This species is currently categorized as near threatened by the IUCN, and previous studies suggest negative effects of projected changes in climate. Using maximum entropy methods we modeled the effects of CC on the current and mid-century distribution of M. sanmartini under two IPCC scenarios - A2 (severe) and B2 (moderate). The effects of LULCC were studied by superimposing the potential distribution with current land use, while future distribution models were evaluated under the scenario of maximum expansion of soybean and afforestation in Uruguay. The results suggest that M. sanmartini is distributed in eastern Uruguay and the south of Brazil, mainly related to hilly and grasslands systems. Currently more than 10% of this species' distribution is superimposed by agricultural crops and exotic forest plantations. Contrasting with a recent modelling study our models suggest an expansion of the distribution of M. sanmartini by mid-century under both climate scenarios. However, despite the rise in climatically suitable areas for the species in the future, LULCC projections indicate that the proportion of modified habitats will occupy up to 25% of the distribution of M. sanmartini. Future change in climate conditions could represent an opportunity for M. sanmartini, but management measures are needed to mitigate the effects of habitat modification in order to ensure its survival and allow the eventual expansion of its distribution.

Plate tectonics, seaways and climate in the historical biogeography of mammals

The marsupial and placental mammals originated at a time when the pattern of geographical barriers (oceans, shallow seas and mountains) was very different from that of today, and climates were warmer. The sequence of changes in these barriers, and their effects on the dispersal of the mammal families and on the faunas of mammals in the different continents, are reviewed. The mammal fauna of South America changed greatly in the Pliocene/Pleistocene, when the newly-complete Panama Isthmus allowed the North American fauna to enter the continent and replace most of the former South American mammal families. Marsupial, but not placental, mammals reached Australia via Antarctica before Australia became isolated, while rats and bats are the only placentals that dispersed naturally from Asia to Australia in the late Cenozoic. Little is known of the early history of the mammal fauna of India. A few mammal families reached Madagascar from Africa in the early Cenozoic over a chain of islands. Africa was isolated for much of the early Cenozoic, though some groups did succeed in entering from Europe. Before the climate cooled in the mid-Cenozoic, the mammal faunas of the Northern Hemisphere were much richer than those of today.

Oviposition activity and seasonal pattern of a population of Aedes (Stegomyia) aegypti (L.) (Diptera: Culicidae) in subtropical Argentina

Monthly oviposition activity and the seasonal density pattern of Aedes aegypti were studied using larvitraps and ovitraps during a research carried out by the Public Health Ministry of Salta Province, in Tartagal, Aguaray and Salvador Mazza cities, in subtropical Argentina. The A. aegypti population was active in both dry and wet seasons with a peak in March, accordant with the heaviest rainfall. From May to November, the immature population level remained low, but increased in December. Ae. aegypti oviposition activity increased during the fall and summer, when the relative humidity was 60% or higher. Eggs were found in large numbers of ovitraps during all seasons but few eggs were observed in each one during winter. The occurrence and the number of eggs laid were variable when both seasons and cities were compared. The reduction of the population during the winter months was related to the low in the relative humidity of the atmosphere. Significant differences were detected between oviposition occurrences in Tartagal and Aguaray and Salvador Mazza cities, but no differences in the number of eggs were observed. Two factors characterize the seasonal distribution pattern of Ae. aegypti in subtropical Argentina, the absence of a break during winter and an oviposition activity concomitant of the high relative humidity of the atmosphere.

Study of the relationship between Aedes (Stegomyia) aegypti egg and adult densities, dengue fever and climate in Mirassol, state of São Paulo, Brazil

The purpose of this study was to examine the relationship between Aedes aegypti egg and adult density indices, dengue fever and climate in Mirassol, state of São Paulo, Brazil, between November 2004-November 2005. Weekly collections of adults and eggs were made using, respectively, manual aspirators and oviposition traps that produced four entomological indices (positivity and average of females and eggs). Weekly incidence coefficients were calculated based on dengue cases. Each week, the data obtained from entomological indices were related to each other, dengue, and climate variables. The first index to show an association with dengue transmission was the female average, followed by female positivity and egg average. Egg positivity did not show a relationship with risk for dengue, but was sensitive to identifying the presence of the vector, principally in dry seasons. The relationship between climatic factors, the vector and the disease found in this study can be widely employed in planning and undertaking dengue surveillance and control activities, but it is a tool that has not been considered by the authorities responsible for controlling the disease. In fact, this relationship permits the use of information about climate for early detection of epidemics and for establishing more effective prevention strategies than currently exist.

Association of Lutzomyia longipalpis (Diptera: Psychodidae) population density with climate variables in Montes Claros, an area of American visceral leishmaniasis transmission in the state of Minas Gerais, Brazil

In the present paper, we evaluate the relationship between climate variables and population density of Lutzomyia longipalpis in Montes Claros, an area of active transmission of American visceral leishmaniasis (AVL) in Brazil. Entomological captures were performed in 10 selected districts of the city, between September 2002-August 2003. A total of 773 specimens of L. longipalpiswere captured in the period and the population density could be associated with local climate variables (cumulative rainfall, average temperature and relative humidity) through a mathematical linear model with a determination coefficient (Rsqr) of 0.752. Although based on an oversimplified statistical analysis, as far as the vector is concerned, this approach showed to be potentially useful as a starting point to guide control measures for AVL in Montes Claros.

Classification of immature mosquito species according to characteristics of the larval habitat in the subtropical province of Chaco, Argentina

To classify mosquito species based on common features of their habitats, samples were obtained fortnightly between June 2001-October 2003 in the subtropical province of Chaco, Argentina. Data on the type of larval habitat, nature of the habitat (artificial or natural), size, depth, location related to sunlight, distance to the neighbouring houses, type of substrate, organic material, vegetation and algae type and their presence were collected. Data on the permanence, temperature, pH, turbidity, colour, odour and movement of the larval habitat's water were also collected. From the cluster analysis, three groups of species associated by their degree of habitat similarity were obtained and are listed below. Group 1 consisted of Aedes aegypti. Group 2 consisted of Culex imitator, Culex davisi, Wyeomyia muehlensi and Toxorhynchites haemorrhoidalis separatus. Within group 3, two subgroups are distinguished: A (Psorophora ferox, Psorophora cyanescens, Psorophora varinervis, Psorophora confinnis, Psorophora cingulata, Ochlerotatus hastatus-oligopistus, Ochlerotatus serratus, Ochlerotatus scapularis, Culex intrincatus, Culex quinquefasciatus, Culex pilosus, Ochlerotatus albifasciatus, Culex bidens) and B (Culex maxi, Culex eduardoi, Culex chidesteri, Uranotaenia lowii, Uranotaenia pulcherrima, Anopheles neomaculipalpus, Anopheles triannulatus, Anopheles albitarsis, Uranotaenia apicalis, Mansonia humeralis and Aedeomyia squamipennis). Principal component analysis indicates that the size of the larval habitats and the presence of aquatic vegetation are the main characteristics that explain the variation among different species. In contrast, water permanence is second in importance. Water temperature, pH and the type of larval habitat are less important in explaining the clustering of species.

O gênero Xylocopa Latreille no Rio Grande do Sul, Brasil (Hymenoptera, Anthophoridae)

The genus Xylocopa Latreille in Rio Grande do Sul, Brazil (Hymenoptera, Anthophoridae). A survey of the genus Xylocopa Latreille, 1802 is given for Rio Grande do Sul, the southernmost State of Brazil. Data are based on several studies on the bee fauna of southern Brazil and on unpublished observations. A key is provided to the species (males and females) and information on distribution, nesting habits and relation to flowers. Rio Grande do Sul is strikingly rich in species of Xylocopa because of the diversity of habitats and its geographic position in the transition of tropical/subtropical to temperate climate. Nineteen species, classified into ten subgenera, have been recorded in Rio Grande do Sul. Here we maintain the subgenera Ioxylocopa, Megaxylocopa and Xylocospila, which were put into synonymy recently by Minckley (1998). The species are: Xylocopa (Dasyxylocopa) bimaculata Friese, 1903; Xylocopa (Ioxylocopa) chrysopoda Schrottky, 1902; Xylocopa (Megaxylocopa) frontalis (Olivier, 1789); Xylocopa (Nanoxylocopa) ciliata Burmeister, 1876; Xylocopa (Neoxylocopa) augusti Lepeletier, 1841; Xylocopa (N.) brasilianorum (Linnaeus, 1767); Xylocopa (N.) haematospila Moure, 1951; Xylocopa (N.) hirsutissima Maidl, 1912; Xylocopa (N.) nigrocincta Smith, 1854; Xylocopa (N.) ordinaria Smith, 1874; Xylocopa (N.) suspecta Moure & Camargo, 1988; Xylocopa (N.) tacanensis Moure, 1949; Xylocopa (Schonnherria) macrops Lepeletier, 1841; Xylocopa (S.) simillima Smith, 1854; Xylocopa (S.) splendidula Lepeletier, 1841; Xylocopa (S.) varians Smith, 1874; Xylocopa (Stenoxylocopa) artifex Smith, 1874; Xylocopa (Xylocopoda) elegans Hurd & Moure, 1963; Xylocopa (Xylocopsis) funesta Maidl, 1912; Xylocopa (Xylocospila) bambusae Schrottky, 1902. Xylocopa tacanensis is for the first time recorded in Brasil.

Effects of forest conversion on the assemblages' structure of aquatic insects in subtropical regions

The effects of forest conversion to agricultural land uses on assemblages of aquatic insects were analyzed in subtropical streams. Organisms and environmental variables were collected in six low-order streams: three streams located in a forested area, and three in areas converted to agricultural land uses. We expected that the aquatic insects' assemblage attributes would be significantly affected by forest conversion, as well as by environmental variables. Streams in converted areas presented lower species richness, abundance and proportion of sensitive insect taxa. The ANOSIM test evidenced strong difference in EPT assemblage structure between streams of forested and converted areas. The ISA test evidenced several EPT genera with high specificity to streams in forested areas and only one genus related to streams in converted areas. Thus, the impacts of the conversion of forested area to agricultural land uses have significantly affected the EPT assemblages, while environmental variables were not affected. We suggest that the effects detected can be influenced by two processes related to vegetation cover: i) lower input of allochthonous material, and ii) increased input of fine sediments in streams draining converted areas.

Balanço geoquímico de solos derivados de rochas básico-ultrabásicas no ambiente subtropical do Rio Grande do Sul

O balanço de massa da intemperização de solos desenvolvidos de rochas básico-ultrabásicas no Rio Grande do Sul, os menos intemperizados constatados até o presente no estado, mostrou nos horizontes superficiais uma concentração relativa mais elevada dos elementos móveis do que nos subsuperficiais, indicando a existência de descontinuidade entre eles. Tais feições, em conjunto com a mineralogia e com a morfologia dos perfis investigados, indicam a ocorrência de eventos erosivo-deposicionais em um passado pedogeneticamente recente, bem como uma contribuição importante de materiais intempericamente menos evoluídos para a composição mineral dos horizontes superficiais. Esses eventos erosivos e o rejuvenescimento superficial dos perfis explicam o pouco desenvolvimento e a semelhança química e mineralógica desses solos com os desenvolvidos de rochas básico-ultrabásicas em regiões temperadas.

Variabilidade de goethita e hematita via dissolução redutiva em solos de região tropical e subtropical

Dezenove amostras de horizontes B latossólicos, uma de B plíntico, uma de B incipiente e uma de horizonte Cr foram submetidas a dissoluções seletivas da goethita e da hematita por ditionito-citratro-bicarbonato de sódio a 20 ºC em intervalos de tempo entre 5 e 3.840 minutos. O diâmetro médio do cristal (DMC), área superficial específica (ASE) e substituição do ferro por Al (substituição por Al3+) da goethita e da hematita nas amostras foram estimados, por difratometria de raios X (DRX), em subamostras não tratadas e em subamostras tratadas selecionadas ao longo das dissoluções seletivas. O controle das fases de goethita e hematita que persistiram após cada etapa da dissolução seletiva foi realizado pelo método da difratometria diferencial de raios X (DDRX). A cinética dissolutiva dos cristais foi descrita por meio da segmentação das curvas de dissolução do ferro no tempo em intervalos em que o comportamento dissolutivo foi linear. As taxas de dissolução nos diferentes segmentos lineares foram estimadas a partir do coeficiente angular da reta relativa a cada segmento. Em amostras goethíticas latossólicas, a metodologia discriminou diferentes fases de goethita (populações heterogêneas) quanto à substituição por Al3+, DMC e ASE e ofereceu condições para classificar o grau de estabilidade da goethita em baixa, média, alta e muito alta estabilidade. Amostras goethíticas oriundas de ambientes pedogênicos jovens e amostras hematíticas latossólicas caracterizaram-se pela maior homogeneidade de seus cristais, classificados como de baixa e média estabilidade. Nas amostras goethíticas, a proporção de cristais com maior estabilidade (alta substituição por Al3+ e cristalinidade) em cada população mostrou associação positiva com a proporção de gibbsita em relação a caulinita nas amostras. A hematita apresentou menor resistência à dissolução por redução em relação à goethita, exceto quando a última combinou baixa substituição por Al3+ e alta ASE. A caracterização de populações heterogêneas de goethita pode ampliar a utilização deste óxido como indicador de processos pedogênicos em solos poligenéticos, bem como contribuir para um melhor entendimento do comportamento químico e físico desses solos.