Toxicity of Azadirachta indica to leaf-cutting ant Atta sexdens rubropilosa (Hymenoptera: Formicidae)

The leaf-cutting ants are responsible for great economical damages in cultivated areas, and because of this characteristic, they have aroused the interest of researchers around the world. Thus, extracts of neem (Azadirachta indica, A. Juss) were tested through ingestion and contact experiments to investigate their toxicity to Atta sexdens rubropilosa workers. Crude extract of neem seed oil was toxic to the ants by ingestion in all concentrations tested but no toxicity was observed in contact experiments. However, crude extract of neem seed paste produced a significant toxicity to workers by ingestion and by contact.

Toxicity of straight-chain fatty acids to leaf-cutting ants Atta sexdens rubropilosa (Hymenoptera: Formicidae) and the symbiotic fungus Leucoagaricus gongylophorus

This work determined toxicity and attractiveness of straight-chain fatty acids (C 5 to C 12) to Atta sexdens rubropilosa (Forel) workers. The effect to the symbiotic fungus, Leucoagaricus gongylophorus (Singer) Möller, was also tested with the fatty acids C 6 to C 12. A strong mortality of leaf-cutting ants that were fed with an artificial diet containing fatty acids C to C at concentrations above 1.0 mg.ml -1 was observed. Rice flakes impregnated with solutions of these fatty acids were repellent to leaf-cutting ants. Contact experiments showed that treatments with C 6 and C 7 at concentration of 100 mg.ml -1 significantly reduced the survival rate of leaf-cutting ants. The fatty acids C 8 to C 11 were toxic to leaf-cutting ants when topically tested at concentration of 200 mg.ml -1. In relation to the fungus' bioassays, the fatty acids C 6 to C 12 at concentration of 0.1 mg.ml -1 inhibited 100% of the fungal development. Although when the concentration was reduced by half no inhibition effects were observed. The results showed that straight-chain fatty acids have desirable properties for controlling leaf-cutting ants since they directly interfere with both organisms of the symbiotic relationship. The potential of fatty acids as well as ways to control leaf-cutting ants with these compounds are discussed in this article.

Acute toxicity of waters from the urban drainage channels of Santos (São Paulo, Brazil)

The objective of this study was to evaluate the toxicity of water which flows toward the beaches of Santos, SP, Brazil. Water samples were collected from eight urban drainage channels and a small creek, in March, April and August 2005. For each sample, some physical-chemical parameters were analyzed: pH, dissolved oxygen, temperature, salinity, presence of free chlorine and total ammonia contents. Acute toxicity tests (48h) with Daphnia similis were also performed with the samples. The level of ammonia was relatively high in the majority of the samples (≥ 1.5 mg/L), and free chlorine was measurable in most of them. Acute toxicity was observed in four water samples (stations 3, 4, 5 and 7), at least in one occasion. The toxicity was positively correlated with the ammonia concentrations and salinity. Because acute toxicity was detected, actions aiming to control the pollution sources and improve the water quality are recommended.

Determination of copper in fish feed by graphite furnace atomic absorption spectrometry using slurry sampling

The present work develops and optimizes a method to determine copper in samples of feces and fish feed by graphite furnace atomic absorption spectrometry (GFAAS) through the direct introduction of slurries of the samples into the spectrometer's graphite tube coated internally with metallic rhodium and tungsten carbide that acts as chemical modifiers. The limits of detection (LOD) and quantification (LOQ) calculated for 20 readings of the blank of the standard slurries (0.50% m/v of feces or feed devoid of copper) were 0.24 and 0.79 μg L -1 for the standard feces slurries and 0.26 and 0.87 μg L -1 for the standard feed slurries. The proposed method was applied in studies of absorption of copper in different fish feeds and their results proved compatible with that obtained from samples mineralized by acid digestion using microwave oven. © Springer Science+Business Media, LLC 2008.

Determination of copper at wide range concentrations using instrumental features of high-resolution continuum source flame atomic absorption spectrometry

This work describes a method to determine Cu at wide range concentrations in a single run without need of further dilutions employing high-resolution continuum source flame atomic absorption spectrometry. Different atomic lines for Cu at 324. 754 nm, 327. 396 nm, 222. 570 nm, 249. 215 nm and 224. 426 nm were evaluated and main figures of merit established. Absorbance measurements at 324. 754 nm, 249. 215 nm and 224. 426 nm allows the determination of Cu in the 0. 07-5. 0 mg L -1, 5. 0-100 mg L -1 and 100-800 mg L -1 concentration intervals respectively with linear correlation coefficients better than 0. 998. Limits of detection were 21 μg L -1, 310 μg L -1 and 1400 μg L -1 for 324. 754 nm, 249. 215 nm and 224. 426 nm, respectively and relative standard deviations (n = 12) were ≤ 2. 7%. The proposed method was applied to water samples spiked with Cu and the results were in agreement at a 95% of confidence level (paired t-test) with those obtained by line-source flame atomic absorption spectrometry.

Evaluation of the toxicity of Virola sebifera crude extracts, fractions and isolated compounds on the nest of leaf-cutting ants

The phytochemical study of Virola sebifera leaves led to the isolation of three lignans: (+)-sesamin, (-)-hinokinin, and (-)-kusunokinin and three flavonoids: quercetin-3-O - L-rhamnoside, quercetin-3-O - D-glucoside, and quercetin-3-methoxy-7-O - D-glucoside by using techniques as high-speed counter-current chromatography and high-performance liquid chromatography. The crude extracts, fractions, and isolated compounds were evaluated for their insecticidal and fungicidal potential against Atta sexdens rubropilosa and its symbiotic fungus Leucoagaricus gongylophorus. The bioassay results showed a high insecticidal activity for the methanol crude extract of the leaves of V. sebifera and its n-hexane, dichloromethane and ethyl acetate fractions. The fungicidal bioassay revealed high toxicity of the lignans against L. gongylophorus. © 2012 Keylla Utherdyany Bicalho et al.

Voltammetric determination of sulfite using graphite paste electrode modified with nanoparticles of copper pentacyanonitrosylferrate

Copper Pentacyanonitrosylferrate (NCuNP) nanoparticles were prepared in formamide solvent. The material was characterized by Infrared (FTIR), X-Ray Diffraction (XRD) and Ultraviolet-Visible (UV-Vis) Spectroscopy. The Cyclic Voltammogram (CV) the modified graphite paste electrode with NCuNP exhibits two redox couples with (Eθ,)1 = 0.29 and (E θ,)2 = 0.86 V attribute at Cu(I)/Cu (II) and Fe(II)(CN)5NO/Fe(III)(CN) 5NO processes, respectively (KCl = 1.0 mol L-1; v = 20 mV s-1). The redox couple with (Eθ,)2 presents an electrocatalytic response for sulfite. The modified graphite paste electrode gives a linear response of 7.0 × 10-4 to 3.0 × 10-2 mol L-1 (r = 0.998), for sulfite determination with Detection Limit (DL) of 1.76 × 10-3 mol L-1 and an amperometric sensitivity of 3.38 mA/mol L-1 and relative standard desviations ± 3% (n=3). ©The Electrochemical Society.

On the application of nanostructured electrodes prepared by Ti/TiO2/WO3 template : A case study of removing toxicity of indigo using visible irradiation

New assays with HepG2 cells indicate that Indigo Carmine (IC), a dye that is widely used as additive in many food and pharmaceutical industries exhibited cytotoxic effects. This work describes the development of a bicomponent nanostructured Ti/TiO2/WO3 electrode prepared by template method and investigates its efficiency in a photoelectrocatalytic method by using visible light irradiation and applied potential of 1V. After 2h of treatment there are reduction of 97% discoloration, 62% of mineralization and formation of three byproducts assigned as: 2-amine-5-sulfo-benzoic acid, 2,3-dioxo-14-indole-5-sulfonic acid, and 2-amino-α-oxo-5-sulfo-benzeneacetic acid were identified by HPLC-MS/MS. But, cytotoxicity was completely removed after 120min of treatment. © 2013 Elsevier Ltd.

Establecimiento de relaciones entre la Comisión y el Consejo Intergubernamental de Países Exportadores de Cobre = Establishment of relations between the Commission and the Intergovernmental Council of Copper Exporting Countries

Incluye Bibliografía

Determination of copper in different ethanolic matrices using a chloropropyl silica gel modified with a nanostructured cubic octa(3-aminopropyl)octasilsesquioxane

The chloropropyl silica gel was modified with octa(3-aminopropyl) octasilsesquioxane and characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), spectroscopies, and surface and area porosity. The specific sorption capacity of metallic ions (Cu2+ and Ni2+) increases in the following solvent order: water < ethanol 42% < ethanol < ketone. The high values of the constant (K) in the order of 103 L mol-1 suggested the high adsorbent capacity of the modified silica (SGAPC) for Cu2+ and Ni2+. SGAPC was applied to a separation column and shows recoveries of around 100% of copper in samples of sugar cane spirit, vodka, ginger brandy, and ethanol fuel. © 2013 Devaney Ribeiro Do Carmo et al.

Toxicity of hydramethylnon to the leaf-cutting ant Atta sexdens rubropilosa forel (hymenoptera: Formicidae)

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

An alternative method for the simultaneous determination of copper and lead for quality control of sugar cane spirit using a nanotube-based sensor

The development of an electroanalytical method for simultaneous determination of copper and lead ions in sugar cane spirit (cachaça) using carbon paste electrode modified with ascorbic acid and carbon nanotubes (CPE-AaCNT) is described. Squarewave voltammetry (SWV) with anodic stripping was employed, and this technique was optimized with respect to the following parameters: frequency (50 Hz), amplitude (100 mV) and scan increment (9 mV). The analytical curves were linear in the range from 0.0900 to 7.00 mg L - 1 for lead and copper. The limits of detection were 48.5 and 23.9 µg L - 1 for lead and copper, respectively. The developed method was applied to the simultaneous determination of copper and lead in five commercial samples of sugar cane spirit. The results were in good agreement with those obtained by F AAS/GF AAS (flame atomic absorption spectrometry/graphite furnace atomic absorption spectrometry) and showed that CPE-AaCNT can be successfully employed in the simultaneous determination of these metals in real sugar cane spirit samples.

Acute toxicity of sodium metabisulphite on mangrove crab Ucides cordatus (Decapoda, Ucididae)

O metabissulfito de sódio é um sal habitualmente usado no cultivo de camarão a fim de se evitar a melanose. Infelizmente o efeito toxicológico deste xenobiótico em caranguejos decápodes é desconhecido. O presente estudo objetiva investigar o LC₅₀ - 96 h do metabissulfito de sódio na espécie Ucides cordatus em manguezal. A coleta dos caranguejos foi realizada nas margens do canal de maré estuarino em Bragança/PA. Os caranguejos foram submetidos a um teste preliminar (screening) e posteriormente ao teste definitivo, e foram expostos a cinco concentrações diferentes e um grupo controle com cinco repetições, com dois caranguejos por recipiente (5 L) durante 96 horas. Houve correlação negativa no aumento da concentração de metabissulfito de sódio com o oxigênio dissolvido e pH. No final do experimento foram obtidos os seguintes níveis de índice de mortalidade em relação s concentrações de metabissulfito de sódio: 100% em 86,0 mg.L^-1, 74% em 62,0 mg.L^-1, 52% em 52,0 mg.L^-1, 44% em 38,0 mg.L^-1. O valor da LC₅₀ 96h para U. cordatus foi determinado em 42,58 mg.L^-1/Na₂S₂O₅. Os resultados indicam que o metabissulfito de sódio é tóxico para U. cordatus e este caranguejo pode ser usado para biomonitoramento do impacto ambiental.

Distribution and availability of copper, iron, manganese and zinc in the archaeological black earth profile from the Amazon region

Os solos de terra preta arqueológica são ricos em matéria orgânica, contêm fragmentos cerâmicos e artefatos líticos e apresentam nutrientes em concentrações mais elevadas do que outros tipos de solos. Com o intuito de contribuir com informações sobre concentrações de micronutrientes disponíveis em solos de terra preta, foram avaliadas através de extrações químicas sequenciais, a distribuição e disponibilidade de Cu, Fe, Mn e Zn em um perfil de terra preta arqueológica no município de Juruti, estado do Pará. As maiores concentrações de Cu, Fe, Mn e Zn no perfil são encontradas na fração residual. Este estudo mostrou que ferro, manganês e zinco são preferencialmente disponíveis a partir das frações, associados aos óxidos de Fe-Mn, variando de 1265,39 a 1818,12 mg kg^-1, 0,83 a 48,51 mg kg^-1 e 1,92 a 12,05 mg kg^-1, respectivamente, e o cobre a partir da matéria orgânica, variando de 0,13 a 0,45 mg kg^-1.

Multivariate curve resolution analysis applied to time-resolved synchrotron X-ray Absorption Spectroscopy monitoring of the activation of copper alumina catalyst

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