Stink bugs (Heteroptera, Pentatomidae) and an unique host plant in the Brazilian subtropics

Stink bugs are seed/fruit sucking insects feeding on an array of host plants. Among them, an exotic tree called privet, Ligustrum lucidum Ait. (Oleaceae), is very common in the urban areas of the Brazilian subtropics, where it is utilized as food source and shelter for over a decem species of bugs, year round. The species composition, their performance and abundance on this host, and possible causes for this association are discussed and illustrated.

Abundancia y distribución de las especies ícticas (Osteichthyes) del río San Francisco-Cosquín, Córdoba, Argentina

It was made the characterization of the San Francisco-Cosquín Mountain River fish community, Córdoba, Argentina. Samples of fish were taken from selected sites from November 1998 to November 1999. Eleven species were recorded, eight of which are first reports for this river. Relative abundance for each species, species richness, diversity and dominance were estimated. Bryconamericus iheringi (Boulenger, 1887) y Jenynsia multidentata (Jenyns, 1842) were the most abundant.

Efectos del herbicida Paraquat sobre el zooplancton

The effects of 0.1; 0.2; 0.4 and 0.8 mlPQ/L were analized on a zooplankton community, to determine the most sensitive species and to analize the occurence of physical abnormalities. A total of 40 taxa were determined. Paraquat affected significantly the zooplankton density but not the species richness. A progressive state of deformation of these organisms was also observed. Paraquat showed to be highly toxic for the zooplankton, so this herbicide should be strictly regulated in aquatic and terrestrial ecosystems.

Ecologia da ictiofauna de um córrego de cabeceira da bacia do alto rio Paraná, Brasil

Ecological studies were conducted in the ichthyofauna of Cedro, a small headwater stream located in a degraded area of State of São Paulo, Brazil, situated in the upper Paraná River basin. These are the results of two non-consecutive years observations and collections in two biotopes of that stream: a pool and a rapid. The ecological characteristics studied change in space and time. The present richness of species is high (21 species), nine of which are constant, six accessory and six accidental. The diversity is low (0.69 to 2.38), and the numeric predominance, from one to three species, occurred in both biotopes. The most frequent species are Poecilia reticulata (Peters, 1859) (28.1%), Corydoras cf. aeneus (Gill, 1858) (20.3%) and Hypostomus cf. ancistroides (Ihering, 1911) (19.8%). The density ranges from 0.7 to 19.8 specimens/m³. The similarity index indicates high similarity between the ichthyofauna (45.0% to 95.0%) inside the same or contiguous biotopes. The evenness (0.46 to 1.0) is comparable to those found in similar studies carried out in other streams.

Mudanças temporais na abundância e diversidade da fauna de peixes do infralitoral raso de uma praia, sul do Brasil

Abundance and diversity of the fish fauna in the shallow infralittoral region of Atami Beach, Paraná, Brazil, were studied through monthly collections between July 1998 and June 1999. A total of 7553 fishes from 70 species and 26 families, mainly juvenile forms, was captured in the area. The mean captures in number of species, number of fish and biomass were larger from the end of spring to the middle of autumn; seasonal tendency in richness, diversity (number) and equitability indices were not observed. The largest mean dissimilarity in the composition of the ichthyofauna occurred between June and May in comparison to the period between July and October. The species that contributed most to this dissimilarity were Selene setapinnis (Mitchill, 1815), Conodon nobilis (Linnaeus, 1758) and Stellifer rastrifer (Jordan, 1889). Three great groups reflecting patterns of temporal occurrence of the most abundant species were identified.

Mamíferos carnívoros e sua relação com a diversidade de hábitats no Parque Nacional dos Aparados da Serra, sul do Brasil

A survey of carnivore mammals was accomplished in Aparados da Serra National Park from February 1998 to March 2000. The park has 10,250 ha and is considered a biodiversity core area of the Atlantic Forest Biosphere Reserve in the Rio Grande do Sul State, Brazil. The landscape is characterized by relatively well preserved relicts of Araucaria angustifolia (Bertol.) Kuntze forest, grasslands and Atlantic Forest, which have contributed for the survival of endangered carnivore mammals. The National Park was divided in a grid of 16 km² cells using a 1:50,000 scale map. The animals were recorded using indirect methods, by identifying signs (scats, tracks) and direct observation in 2.5 km long and 5 m wide transects, with 10 replicates in each grid cell. Interviews with local people were also used to confirm the animal presence. A total of 13 species was recorded: Procyon cancrivorus (Cuvier, 1798), Pseudalopex gymnocercus (G. Fischer, 1814), Leopardus pardalis (Linnaeus, 1758) and Cerdocyon thous (Linnaeus, 1766) were the most frequent species registered. Nasua nasua (Linnaeus 1766), Herpailurus yaguarondi (Lacépède, 1809), Chrysocyon brachyurus (Illiger, 1815), Eira barbara (Linnaeus, 1758), Leopardus sp., Puma concolor (Linnaeus, 1771), Galictis cuja (Molina, 1782), Conepatus chinga (Molina, 1892) and Lontra longicaudis (Olfers, 1818) showed lower frequencies. The Park presented areas with significant differences (Mantel Test, P< 0.05) in species richness and composition related to habitat classes. Areas with high habitat richness presented high species richness. The Araucaria forest was the habitat that presented the higher carnivore richness. The border areas of the Park are influenced by several environmental degradation factors that could be affecting the distribution of carnivores.

Ecology of colonizing populations of the figfly Zaprionus indianus (Diptera, Drosophilidae) in Porto Alegre, Southern Brazil

Ecological parameters such as trophic niche overlap and niche breadth were computed from the frequency of all drosophilid species collected in 2001 and 2002, in the urban area of Porto Alegre city, Brazil. Independently of place, drosophilids community composition and components breeding or feeding sites, the highest frequencies of Zaprionus indianus (Gupta, 1970) were obtained during seasons with higher average temperatures, especially during summer. From a total of the 19,146 individuals of Z. indianus sampled, 80% were found in this season. The data of trophic niche breadth suggest a higher opportunism of adult flies in feeding substrate use, but the females are still selective in oviposition substrate choice. For the values of niche overlap, only for some species, did we find any correlation between these and species richness and/or number of resources, and the most of the correlation values considering breeding and feeding sites were positive. The colonization of Z. indianus in Porto Alegre could be leading to adjustments in the survival strategies of the resident species, but it is possible that many species have conditions for coexisting with the invader.

Composition and diversity of Trichoptera (Insecta) larvae communities in the middle section of the Jacuí river and some tributaries, State of Rio Grande do Sul, Brazil

The taxonomic composition and diversity of Trichoptera larvae communities were studied in four lotic sites in central region of State of Rio Grande do Sul. Sampling was done monthly from June, 2001 to May, 2002 in four sites located at the middle section of Jacuí River (Point 4) and in three tributaries (Carijinho River - Point 1; Lajeado da Gringa - Point 2 and Lajeado do Gringo - Point 3), with a Surber sampler. The total number of larvae collected was 29,143, belonging to 25 genera distributed in nine families; twenty of these genera are new records for the State. The highest abundance was found at Point 2 (n = 12,547). The highest standardized richness, for a 1,177 specimens sample chosen by chance, was recorded at Point 1, followed by Point 4 (17.7 and 16 genera, respectively). The highest diversity was found at Point 1, and the lowest at Point 3 (H' = 1.31 and H' = 0.77, respectively). Point 1 had the lowest anthropic influence and the best preserved riparian vegetation, while Point 3 presented the highest anthropic impact, and a very reduced riparian vegetation. The diversity of Trichoptera observed in this study is low, compared to the estimated maximum theoretical diversity. Low diversity values are related to the low evenness, since the richness was relatively high. The Trichoptera larvae communities seem to be related to the food availability and physical features (riparian vegetation and anthropic influence) of the study sites.

Reproductive ecology of the invader species gekkonid lizard Hemidactylus mabouia in an area of southeastern Brazil

Hemidactylus mabouia Moreau de Jonnés, 1818 is a "fixed" clutch size exotic species well established in Brazil. In this paper we investigate some reproductive strategies adopted to minimize the costs of invariant clutch size to this invader species living in an environment with marked climatic seasonality in Southeastern Brazil (22°56’S; 46°55’W). The study was carried out from April 2002 to March 2003. Females and males attain maturity at 47.9mm and 46.9mm SVL, respectively. Larger females tended to produce larger eggs. The reproduction occurred throughout the year, but only at the wet season the females increase the clutch frequency. There was a significant variation in mean testis volume among the months throughout the year and the largest means were recorded between August and December. Maternal investment on egg size, increase on clutch frequency and seasonal increase on testis volume can represent important reproductive strategies of this invader species living in an non-urban habitat whit climatic seasonality (dry and cold weather season).

Two decades of colonization of the urban environment of Porto Alegre, southern Brazil, by Drosophila paulistorum (Diptera, Drosophilidae)

Drosophila paulistorum Dobzhansky & Pavan, 1949 had initially been considered absent in anthropogenically disturbed environments, but in 1985 the detection of the species in Porto Alegre city, southern Brazil, suggested its potential to colonize new habitats and laid the foundations for ecologic studies on this species' populations. This study followed the variations in D. paulistorum populations in this town almost 20 years after its first local record. Drosophilid specimens were collected in sites with different urbanization grades and the results point to the expressive decline in D. paulistorum populations in Porto Alegre. This decline may be linked to urban growth and to naturally driven population decline, as imputed to climatic changes like variations in maximum and minimum temperatures as a consequence of a global climate warming. Also, the recent introduction of exotic species Zaprionus indianus Gupta, 1970 seems to play a role in this scenario, changing the interactions between native species.

Composition and diversity of Ephemeroptera (Insecta) nymph communities in the middle section of the Jacuí River and some tributaries, southern Brazil

The taxonomic composition and diversity of assemblages of Ephemeroptera nymphs of four lotic environments in the central region of State of Rio Grande do Sul, a subtropical area in southern Brazil, were evaluated. Samplings were done monthly, with a Surber sampler, from June 2001 to May 2002, in the Jacuí River and three of its tributaries. The total number of nymphs collected in the four sampling sites was 11,007 in five families and 19 genera, of these, 11 are new records for the State. The highest diversity occurred in Point 4 (H'=2.41) and the lowest in Point 2 (H'=1.69). Point 4 had the highest environmental stability, conservation of the riparian vegetation and the lowest anthropic impact, while Point 2 presented a large environmental simplification due to a direct anthropic influence (e.g. domestic sewerage, trampling by cattle). The diversity of nymphs observed in the total area is high, compared to the estimated maximum theoretical diversity; a result of the high evenness and richness recorded. Rarefaction curves, calculated for a sample of 1,018 specimens, showed a similar expectation of richness for the four sampling sites. This result seems to be associated with the overall environmental homogeneity of the region caused by long-term alterations (land use and deforestation). In summary, higher diversity of Ephemeroptera nymph assemblages seems to be associated with habitat complexity, a good vegetation cover and a lower anthropic influence.

Seasonal dynamics of a drosophilid (Diptera) assemblage and its potencial as bioindicator in open environments

Drosophila Fallen, 1823 (Diptera, Drosophilidae) is for long a well-established model organism for genetics and evolutionary research. The ecology of these flies, however, has only recently been better studied. Recent papers show that Drosophila assemblies can be used as bioindicators of forested environment degradation. In this work the bioindicator potential of drosophilids was evaluated in a naturally opened environment, a coastal strand-forest (restinga). Data from nine consecutive seasonal collections revealed strong temporal fluctuation pattern of the majority of Drosophila species groups. Drosophila willistoni group was more abundant at autumns, whereas D. cardini and D. tripunctata groups were, respectively, expressive at winters and springs, and D. repleta group at both seasons. The exotic species D. simulans Sturtevant, 1919 (from D. melanogaster group) and Zaprionus indianus Gupta, 1970 were most abundant at summers. Overall, the assemblage structure did not show the same characteristics of forested or urban environments, but was similar to the forests at winters and to cities at summers. This raises the question that this locality may already been under urbanization impact. Also, this can be interpreted as an easily invaded site for exotic species, what might lead to biotic homogenization and therefore can put in check the usage of drosophilid assemblages as bioindicators at open environments.

Fish assemblages in two sandy beaches in lower Purus river, Amazonas, Brazil

Fish assemblages from two sandy beaches in the lower Purus river (Amazonas, Brazil) were compared. Four sampling groups were represented by: day and night samples in sandy beach inside the Reserva Biológica de Abufari (biological reserve) and day and night samples in the Reserva de Desenvolvimento Sustentável Piagaçu-Purus (sustainable development reserve). Samples were collected during low water levels (November) in 2007. The fish were sampled by means of seines with mesh size of 5 mm between opposing knots, 11 m long and 6 m wide. A total of 112 fish species belonging to nine orders and 27 families was captured. The vast majority of the dominant forms consisted of small fishes (< 100 mm SL) or juveniles. Samples collected in Abufari at night presented more specimens (3,540), higher richness (84 spp.), larger total biomass (76,614 g) and higher diversity (H'= 2.57) than the other groups. The composition of fish assemblages was significantly different among all analyzed groups (ANOSIM, p < 0.0001, R= 0.71). NMDS analysis also clustered all species in four distinct groups according to species composition per period and site. SIMPER analyses showed that 80% of variation of species composition among the groups examined was due to 12 species. However, fish composition did not show any correlation with the abiotic factors examined. Different levels of use in both reserves may explain differences in fish composition.

Composition and structure of a Miridae (Hemiptera, Heteroptera) assemblage from a relict of deciduous rainforest in southern Brazil

A two-year study was carried out to evaluate the composition, abundance and species richness of Miridae from Parque Estadual do Turvo, municipality of Derrubadas, state of Rio Grande do Sul, Brazil. Samplings were made in the springs of 2003 and 2004 (October), and autumns of 2004 and 2005 (May), using a beating tray method, along two trails of the park. Sampling effort (hours x collectors) in the quantitative collections totaled 153 hours. Two-hundred mirid specimens of 50 species were collected. The most abundant mirid was Prepops setosipes (Reuter, 1910), representing 23% of the collected individuals, followed by Collaria capixaba Carvalho & Fontes, 1981 (10.5%) and Tropidosteptes cribratus (Stål, 1860) (7%), the latter recorded in all sampling periods. The highest abundance was observed in the springs of 2003 and 2004, with 53 and 78 individuals, respectively. Rarefaction method showed that estimated species richness was higher in autumn/2004 than in the other sampling periods, and higher along Yucumã than in Garcia trail. Besides a higher species richeness, Yucumã had more exclusive species than Garcia trail. The percent of species represented by one or two specimens in quantitative samplings (singletons and doubletons) was 60%. Additional samplings including hand collection, random beating tray and light trap collections added 20 species not recorded in the quantitative samplings.

Diversity and structure of microcrustacean assemblages (Cladocera and Copepoda) and limnological variability in perennial and intermittent pools in a semi-arid region, Bahia, Brazil

Temporary wetlands undergo recurrent drought due to the scarcity of water, which disrupts the hydrological connectivity with adjacent aquatic systems. However, some environments retain water for longer periods, allowing greater persistence of the community. The current study evaluated differences in the microcrustacean assemblages and limnological variability between perennial and intermittent pools in a semi-arid region of Brazil. The abiotic features (water temperature, pH, total alkalinity, electrical conductivity and depth) of intermittent pools were affected more than perennial pools due to loss of water volume. This may have contributed to a higher average richness and diversity index in some intermittent pools and differences in the structure of the assemblages. The lowest species richness and diversity were recorded where physical factors, such as a large quantity of suspended solids and variability in the electrical conductivity of the water and pH, make the environment unsuitable for these organisms. These results suggest that community development in intermittent pools is interrupted by the dry season; when the water returns, due to rainfall or rising groundwater, each pond undergoes a different process of colonization. In these circumstances, the biological importance of temporary aquatic environments is clear, since such pools provide shelters and have an important role in the maintenance of the regional diversity of aquatic environments.