Qualidade microbiológica da água da cultura do arroz irrigado, no sul do Brasil

Total and fecal coliforms are bio-indicators of the environmental impact caused by anthropic action and are considered indicators of the microbiological quality of the water. In the cultivation of rice by irrigation much water is used and care in water management is required in order to increase the volume and quality of production while reducing the environmental impact. The objective of this research is to evaluate the quality of the irrigation water used in five rice-growing regions of the State of Rio Grande do Sul during the vegetative and reproductive phases. The results demonstrate that the indices of total and fecal coliforms in the rice field plots of the fields in all the rice producing regions of Rio Grande do Sul evaluated in this study were lower in the reproductive than in the vegetative phases. The irrigation channel presented low indices of fecal coliforms but a higher incidence of total coliforms. The data demonstrated that irrigated rice cultivation can alter the microbiological quality of the water in the plots by its potential capacity of circulating the nutrients with the result that the drainage water presents a smaller quantity of contaminating microbial agents.Key words: water, irrigation, fecal coliforms, rice fields.Os coliformes totais e fecais são bioindicadores de impacto ambiental causado por ação antrópica, sendo considerados indicadores de qualidade microbiológica da água. Na cultura do arroz irrigado, onde é necessário o uso da água, devem-se ter cuidados relacionados ao manejo, visando aumento de produção e qualidade do produto, com redução do impacto ambiental. O objetivo da pesquisa foi avaliar a qualidade microbiológica da água de irrigação, em cinco regiões orizícolas do Rio Grande do Sul, nas fases vegetativa e reprodutiva. As amostras de água foram submetidas à análise da qualidade microbiológica, sendo adotado o método de indicadores de poluição que estabelece simultaneamente a concentração de coliformes fecais e totais, através da análise bioquímica pelo método Colilert® (IDEXX). Os resultados mostram que os índices de coliformes totais e fecais nas parcelas de arroz, de todas as regiões produtoras do Rio Grande do Sul, avaliadas no presente estudo, foram inferiores na fase reprodutiva da cultura quando comparados a sua fase vegetativa. O canal de irrigação apresentou baixos índices de coliformes fecais, no entanto, a presença de coliformes totais mostrou-se mais elevada. Os dados apresentados demonstram que a orizicultura pode alterar a qualidade microbiológica da água presente nas parcelas, devido ao seu potencial de ciclagem de nutrientes, fazendo com que a água de drenagem apresente menor quantidade de agentes microbianos contaminantes. Palavras-chave: água, irrigação, coliformes, campos de arroz

AGROECOSSISTEMAS ORIZÍCOLAS IRRIGADOS: INSETOS-PRAGA, INIMIGOS NATURAIS E MANEJO INTEGRADO

Pest insects are considered throughout the world as a major limitation to the production of irrigated rice crops. Many different control methods have been devised in attempts to reduce such losses. However, the continuous use of phytosanitary products induce resistance formation in the targeted insect pests, in addition to increasing the abundance of other secondary pests. Biological control through the use of natural enemies like predators, parasitoids and diseases surged as an alternative method for controlling insect pests in the field by reducing their population sizes and, consequently, the damage to their host plants. The present review presents the results of research on pest insects of rice cultures and revisits the importance of their natural enemies as biological control agents in an Integrated Pest Management context.Nos ecossistemas de produção de arroz irrigado, os insetos-praga são considerados uma das limitações na produção mundial. Diante desse fato, diversas formas de controle vêm sendo pesquisadas para minimizar o problema. O uso contínuo de produtos fitossanitários ocasiona a resistência das pragas, além do aumento da população de pragas secundárias. Como alternativa, o uso do controle biológico, através de inimigos naturais, como predadores, parasitóides e patógenos, se revela capaz de regular as pragas em seu ambiente natural, reduzindo a densidade das populações e conseqüentemente os danos às plantas hospedeiras. Sendo assim, nesse trabalho de revisão são apresentados dados sobre a cultura orizícola, a ocorrência de insetos-praga, bem como a importância dos inimigos naturais como forma de controle biológico e aplicação no Manejo Integrado de Pragas

Dolabelladienols A–C, New Diterpenes Isolated from Brazilian Brown Alga Dictyota pfaffii

[Abstract:]The marine brown alga Dictyota pfaffii from Atol das Rocas, in Northeast Brazil is a rich source of dolabellane diterpene, which has the potential to be used in future antiviral drugs by inhibiting reverse transcriptase (RT) of HIV-1. Reexamination of the minor diterpene constituents yielded three new dolabellane diterpenes, (1R*,2E,4R*,7S,10S*,11S*,12R*)10,18-diacetoxy-7-hydroxy-2,8(17)-dolabelladiene (1), (1R*,2E,4R*,7R*,10S*,11S*,12R*)10,18-diacetoxy-7-hydroxy-2,8(17)-dolabelladiene (2), (1R*,2E,4R*,8E,10S*,11S,12R*)10,18-diacetoxy-7-hydroxy-2,8-dolabelladiene (3), termed dolabelladienols A–C (1–3) respectively, in addition to the known dolabellane diterpenes (4–6). The elucidation of the compounds 1–3 was assigned by 1D and 2D NMR, MS, optical rotation and molecular modeling, along with the relative configuration of compound 4 and the absolute configuration of 5 by X-ray diffraction. The potent anti-HIV-1 activities displayed by compounds 1 and 2 (IC50 = 2.9 and 4.1 μM), which were more active than even the known dolabelladienetriol 4, and the low cytotoxic activity against MT-2 lymphocyte tumor cells indicated that these compounds are promising anti-HIV-1 agents.Brasil. Conselho Nacional de Desenvolvimento Científico e Tecnológico; 490425/2010-0Brasil. Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro ; E-26/103.176/2011Ministerio de Economia y Competitividad; AGL2012-12266-C0

91. Biodiversidade e Abundância de Insetos e Seletividade de Inseticidas na EEA-IRGA, Cachoeirinha, RS

Introdução: Os ecossistemas que compreendem as áreas de arroz irrigado e seus arredores abrigam uma grande diversidade de insetos (Hook, 1994). Muitos possuem importância para o homem, dentre eles os insetos-praga, que podem causar grandes impactos e prejuízos em lavouras orizícolas devido aos seus hábitos alimentares e reprodutivos. Outros insetos fazem parte desses agroecossistemas, como os inimigos-naturais, que compreendem predadores e parasitóides, que auxiliam no controle de insetospraga, desempenhando um papel fundamental no Manejo Integrado de Pragas (Heinrichs e Barrion, 2004). Nesse contexto, esse estudo objetivou avaliar a biodiversidade abundância de insetos, e a seletividade de inseticidas nas áreas de arroz irrigado na Estação Experimental do Arroz, do Instituto Rio Grandense do Arroz, Cachoeirinha, RS, no período agrícola 2008/09

91. Biodiversidade e Abundância de Insetos e Seletividade de Inseticidas na EEA-IRGA, Cachoeirinha, RS

Introdução: Os ecossistemas que compreendem as áreas de arroz irrigado e seus arredores abrigam uma grande diversidade de insetos (Hook, 1994). Muitos possuem importância para o homem, dentre eles os insetos-praga, que podem causar grandes impactos e prejuízos em lavouras orizícolas devido aos seus hábitos alimentares e reprodutivos. Outros insetos fazem parte desses agroecossistemas, como os inimigos-naturais, que compreendem predadores e parasitóides, que auxiliam no controle de insetospraga, desempenhando um papel fundamental no Manejo Integrado de Pragas (Heinrichs e Barrion, 2004). Nesse contexto, esse estudo objetivou avaliar a biodiversidade abundância de insetos, e a seletividade de inseticidas nas áreas de arroz irrigado na Estação Experimental do Arroz, do Instituto Rio Grandense do Arroz, Cachoeirinha, RS, no período agrícola 2008/09

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO

Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO

Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy

We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we obtain a radiation energy of 15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principle calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the direct calibration of any cosmic-ray radio detector against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI. Supplemental material in the ancillary file