RESUMO

Soilless cultivation of strawberry is in expansion in Brazil due to factors like the reduction of phytosanitary problems and the possibility of extending the crop period, as well as the ergonometric facility for management of the culture. However, black fungus gnats (Sciaridae, Diptera) are ubiquitous pests in the greenhouse production system, causing direct and indirect damage to plants. ThIS study evaluated the occurrence of black fungus gnats species in semi-hydroponic cultivation of strawberry and to identify the species, as well as to describe the symptoms in infested plants. The research was developed in commercial productions of strawberry, in five municipalities (Arroio do Padre, Canguçu, Capão do Leão, Pelotas and Turuçu) during July to December 2017, where adult samples were collected twice a month, with petri dish traps containing water and neutral detergent placed inside the greenhouses between the plants. A total of 2030 adult gnats belonging to two species were collected. Bradysia aff. impatiens, accounted with 90.79% of the total, and Bradysia aff. ocellaris, accounted with 9.21%. In order to assist the correct determination of species, males of both species were identified and illustrated. With respect to the symptoms observed during the research, it was possible to verify since the wilted crown of plants to the death of plants, which were confirmed by the presence of larvae in the root system. As the occurrence of these insects is recent in strawberry, there is no pesticide registered in Brazil, so management strategies (cultural, physical, and sanitary) also are discussed.

O cultivo de morango sem solo está em expansão no Brasil, devido a fatores como a redução de problemas fitossanitários e a possibilidade de produção por um período maior, assim como a facilidade ergométrica para o manejo da cultura. No entanto, black fungus gnats (Diptera: Sciaridae) são pragas onipresentes no sistema de produção de estufas, causando danos diretos e indiretos às plantas. O objetivo deste trabalho foi avaliar a ocorrência de espécies de black fungus gnats em cultivo de morango semi-hidropônico e identificar as espécies, assim como descrever os sintomas observados em plantas infestadas. O trabalho foi desenvolvido em produção de morango comercial, em cinco municípios (Arroio do Padre, Canguçu, Capão do Leão, Pelotas e Turuçu) durante Julho a Dezembro de 2017, onde os adultos foram coletados duas vezes por mês, com armadilhas de placa de Petri, contendo água e detergente neutro, as quais eram colocadas dentro das estufas entre as plantas. Um total de 2.030 mosquitos adultos pertencentes a duas espécies foram coletados. Bradysia aff. impatiens, com 90,79% do total, e Bradysia aff. ocellaris, com 9,21%. Para auxiliar na correta determinação das espécies, os machos de ambas as espécies foram identificados e ilustrados. Com relação aos sintomas observados durante o trabalho, foi possível verificar desde a coroa murcha até a morte das plantas, em que foram confirmados pela presença de larvas no sistema radicular. Como a ocorrência desses insetos é recente em morango, não há agrotóxico registrado no Brasil, então estratégias de manejo (cultural, físico e sanitário) também são discutidas.

Assuntos

RESUMO

An effective approach to the digestion of fluoropolymers for the determination of Ag, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, and Ni impurities has been developed using microwave-induced combustion (MIC) in closed quartz vessels pressurized with oxygen. Samples that were examined included the following: polytetrafluorethylene (PTFE); polytetrafluoroethylene with an additional modifier, perfluoropropylvinylether (PTFE-TFM); and fluorinated ethylene propylene (FEP). A quartz device was used as a sample holder, and the influence of the absorber solution was evaluated. Determination of trace elements was performed by inductively coupled plasma-optical emission and mass spectrometry. Neutron activation analysis (NAA) was used for validation purposes. Results were also compared to those obtained using microwave-assisted acid extraction in high-pressure closed systems. Dilute nitric acid (5 mol L(-1)), which was selected as the absorbing medium, was used to reflux the sample for 5 min after the combustion. Using these conditions, agreement for all analytes was better than 98% when compared to values determined by NAA. The residual carbon content in the digests was lower than 1%, illustrating the high efficiency of the method. Up to 8 samples could be digested within 30 min using MIC, providing a suitable throughput, taking into account the inertness of such samples.

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RESUMO

The present work evaluated the use of iridium (Ir) as permanent modifier for the determination of total selenium in urine and serum by graphite furnace atomic absorption spectrometry. Concerning urine, the presence of trimethylselenonium (TMSe(+)) was especially considered. Pyrolysis and atomization temperatures of 1,000 and 2,100 degrees C, respectively, were used. For nondigested urine and serum samples, 0.2% v/v HNO(3) and Triton X-100 were used as diluents, respectively, and the same initial platform Ir treatment was effective for up to 1,100 atomization cycles. Good precision [less than 5% relative standard deviation (RSD)] can be achieved with the proposed method. Low TMSe(+) recovery was observed for nondigested urine samples. Thus, if this species is to be considered in urine analysis, a previous external mineralization step was found to be necessary. Alternatively, an in situ oxidation treatment was developed. Detection limits of 8, 10, and 7 mug l(-1) were obtained after dilution, microwave-assisted digestion, and in situ oxidation procedures, respectively. The accuracy of the method was validated by the analysis of certified reference or commercial quality control materials and spiked samples.

Assuntos