ABSTRACT. This study evaluates the effects of agricultural and urban activities on the structure and composition of benthic communities of streams in the state of Rio Grande do Sul, Brazil. Benthic macroinvertebrates were collected in streams influenced by urbanization and agriculture and in streams with no anthropogenic disturbances (reference streams). Organism density was superior in urban streams when compared with streams in the other two areas. The taxonomic richness and Shannon diversity index were higher in reference streams. The benthic fauna composition was significantly different among land uses. The classification and ordination analyses corroborated the results of variance analyses demonstrating the formation of clusters corresponding to streams with similar land use. Seasonality was also found to influence the benthic community, though in a lesser degree than land use.

AIMS: The objective of this study was to evaluate the effects of urban environments on the distribution and occurrence of aquatic Ephemeroptera, Plecoptera and Trichoptera (EPT) insects in six urban subtropical streams; METHODS: Organisms were collected with a Surber sampler in 2005 and 2006, over two hydrological cycles. We analyzed abundance values, taxonomic richness, Shannon-Wiener diversity and Pielou's evenness. A principal components analysis (PCA) was performed to evaluate the environmental variability of streams. A canonical correspondence analysis (CCA) was performed to evaluate the possible effects of environmental variables; RESULTS: The PCA ordered the streams according to their quality, and Suzana and Nadau streams had higher concentrations of nutrients. The Baetidae (Ephemeroptera) was the family with the highest number of genera (18). Perissophlebiodes Savage, 1983, and Americabaetis Kluge, 1992, were the most common genera. Anacroneuria Klapálek, 1909, was the most abundant Pleocoptera, and Smicridea McLachlan, 1871, was the dominant Trichoptera genus. In the CCA, pH, electrical conductivity and stream velocity were positively correlated with axis 1, whereas dissolved oxygen was negatively correlated with axis 1; CONCLUSIONS: Our results show that the distribution of EPT in urban streams is affected by changes in water physicochemical characteristics. However, these changes are not sufficiently severe to cause the elimination of EPT.

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-Landscape is important in determining the composition of aquatic assemblage, and benthic invertebrates, particularly Chironomidae, are often used as bioindicators of environmental quality because their occurrence and distribution are influenced by different land uses. The objective of this study was to evaluate the influence of different land uses, considering three landscape scales (drainage basins, riparian buffer and streams), on chironomid assemblage. We sampled streams located in an agricultural matrix by collecting chironomid larvae and water samples and performed a landscape analysis using Geographical Information System techniques. The drainage basins had a high percentage of agricultural land use; in all of the drainage basins studied, 79% of the riparian buffer was not in accordance with Brazilian law. Cricotopus proved to be a good indicator of the agricultural conditions, whereas Thienemanniella and Rheotanytarsus proved to be indicators of exposed soil. Lopescladius was more sensitive to disturbance and was positively correlated with the presence of riparian vegetation. Although the variables at the local scale (stream) were responsible for a major change in the assemblage, the landscape attributes at large scales (drainage basin and riparian buffer) generated significant effects on Chironomidae fauna. Our results suggest the importance of the conservation of two larger landscape scales to support the equilibrium and maintenance of aquatic assemblage.

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A produção brasileira de grãos na safra de 2006/2007 foi estimada em 130,5 milhões de toneladas, destacando-se entre outras, as culturas de soja, milho, arroz e trigo, sendo estas de grande importância no cenário agrícola do Brasil (Companhia Nacional de Abastecimento -Conab 2008). Mundialmente, a produção de milho chega a 615,92 milhões de toneladas, atrás apenas do trigo (Cocamar 2004).Os insetos causam freqüentemente danos extensivos aos grãos armazenados e aos produtos destes grãos. As perdas quantitativas podem atingir 5-10% nas regiões temperadas e 20-30% nas regiões tropicais (Haque et al. 2000). De acordo com Silva et al. (2007) ). Countless problems due to the use of chemical insecticides for the control of pests in stored grains have been observed. In order to minimize these problems, alternative measures have been developed, including the use of botanical insecticides. This work was carried out with the objective of evaluating the effect of the essential oil of Tagetes patula L. on, Sitophilus zeamais (Mots., 1855) in corn kernels in laboratory conditions. The T. patula essential oil was obtained through hidrodestilation with the Clevenger device. The chemical characterization of the compounds found in the essential oil of T. patula was carried by gas chromatography connected to the mass spectrometer. The compounds found were: limonene (37.05%), terpinolene (32.61%), piperitone (14.40%), neophitadiene (5.91%), sabinene (2.88%), trans-ocimene (2.02%), beta-cariphilene (1.98%), farnesol (1.84%), and alpha-pinene (1.30%). The insects used in the bio-test were kept under controled temperature and relative humidity environment. Two bioassays were carried out to evaluate the effect of the essential oil of T. patula on the behavior (activity/repellence) and insecticide activity on adults of S. zeamais. The results showed that this essential oil was efficient (concentration of 10 µL) to control adults of S. zeamais adults.

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Influence of land-use on structural and functional macroinvertebrate composition communities associated on detritus in Subtropical Atlantic Forest streamsInfluência do uso da terra sobre a composição estrutural e funcional da comunidade de macroinvertebrados associados a detritos em riachos subtropicais da Floresta Atlântica Abstract: Aim: Our aim in this study was to evaluate the effects of land use in drainage basins of the streams on the taxonomic and functional composition of aquatic invertebrate communities associated in leaf litter. Methods: We evaluated the colonisation of invertebrates in the incubated plant debris in streams with presence and absence of riparian vegetation and different land-uses in the drainage area. We used the litter bags approach. Results: The taxonomic and functional composition invertebrate associated with leaf litter ranged between streams. In addition, streams with presence of vegetation showed less variation taxonomic and functional composition communities. Still, the density of shredders invertebrates were lower in streams without vegetation. Conclusions: The riparian vegetation is an important environmental factor in the composition of invertebrates. However, the land-use throughout the drainage basin should be considered as relevant factor in structuring aquatic biota.