Efficiency of the induced mating technique for Toxorhynchites theobaldi (Diptera, Culicidae)

Toxorhynchites mosquitoes play important ecological roles in aquatic microenvironments, and are frequently investigated as potential biological control agents of mosquito disease vectors. Establishment of Toxorhynchites laboratory colonies can be challenging because for some species, mating and insemination either do not occur or require a prohibitive amount of laboratory space for success. Consequently, artificial insemination techniques have been developed to assist with mass rearing of these species. Herein we describe an adapted protocol for colony establishment of T. theobaldi, a species with broad distribution in the Neotropics. The success of the technique and its implications are discussed.

DESENVOLVIMENTO, AUTOMAÇÃO E DESEMPENHO DE UM CONSOLIDÔMETRO COM INTERFACE HOMEM-MÁQUINA

O ensaio de consolidação preconiza a utilização de um consolidômetro. Esse equipamento, até então, não era produzido e comercializado no Brasil. Os modelos não automatizados disponíveis para importação, apesar da proposta de baixo custo, ainda são rústicos e necessitam de contínua calibração dos níveis de pressão durante a realização do ensaio. A exclusividade e intervenção de um técnico durante todo o ensaio, associada à precária coleta de dados nesses modelos, ainda são os principais fatores que têm inviabilizado a consolidação desse ensaio na ciência do solo brasileira. Como alternativa a esses problemas, este trabalho teve por objetivos desenvolver e automatizar um consolidômetro a partir de um Controlador Lógico Programável (CLP) com interface homem-máquina (IHM). O equipamento é constituído de um gabinete de metal que aloja conjuntos de dispositivos pneumáticos, eletrônico-digital e atuadores de força e posição. O funcionamento de cada dispositivo de forma isolado ou conjugado é gerenciado por meio de um software em linguagem de programação ladder, que, a partir de um CLP com IHM incorporada, possibilita armazenar instruções e implementar funções. A interface entre o PC e o consolidômetro é feita pelo software CA-Linker, v 1.0, projetado especificamente para o equipamento. O uso do CLP com IHM incorporada permitiu o desenvolvimento e a automação do consolidômetro. O desempenho e a eficiência do conjunto de dispositivos (pneumáticos, eletrônico-digital e atuadores de força e pressão) foram comprovados pelos excelentes resultados dos valores de deformação e pressão obtidos em função do tempo e, principalmente, do comportamento da curva de compressão, gerada pelos ensaios de compressão.

Occurrence and Structure of Arbuscular Mycorrhizal Fungal Communities in Cassava after Cultivation of Cover Crops as Observed by the “PCR-DGGE” Technique

ABSTRACT Cassava (Manihot esculenta Crantz) is a highly mycotrophic crop, and prior soil cover may affect the density of arbuscular mycorrhizal fungi (AMFs), as well as the composition of the AMFs community in the soil. The aim of this study was to evaluate the occurrence and the structure of AMFs communities in cassava grown after different cover crops, and the effect of the cover crop on mineral nutrition and cassava yield under an organic farming system. The occurrence and structure of the AMFs community was evaluated through polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE). A randomized block experimental design was used with four replications. Six different cover crop management systems before cassava were evaluated: black oats, vetch, oilseed radish, intercropped oats + vetch, intercropped oats + vetch + oilseed radish, plus a control (fallow) treatment mowed every 15 days. Oats as a single crop or oats intercropped with vetch or with oilseed radish increased AMFs inoculum potential in soil with a low number of propagules, thus benefiting mycorrhizal colonization of cassava root. The treatments did not affect the structure of AMFs communities in the soil since the AMFs communities were similar in cassava roots in succession to different cover crops. AMFs colonization was high despite high P availability in the soil. The cassava crop yield was above the regional average, and P levels in the leaves were adequate, regardless of which cover crop treatments were used. One cover crop cycle prior to the cassava crop was not enough to observe a significant response in variables, P in plant tissue, crop yield, and occurrence and structure of AMFs communities in the soil. In the cassava roots in succession, the plant developmental stage affected the groupings of the structure of the AMF community.

Interface de recuperación para catálogos en línea con salidas ordenadas por probable relevancia

Se presenta el desarrollo de una interface de recuperación de información para catálogos en línea de acceso público (plataforma CDS/ISIS), basada en el concepto de similaridad para generar los resultados de una búsqueda ordenados por posible relevancia. Se expresan los fundamentos teóricos involucrados, para luego detallar la forma en que se efectuó su aplicación tecnológica, explícita a nivel de programación. Para finalizar se esbozan los problemas de implementación según el entorno.

Yield and performance of sugarcane in on-farm interface with rubber in Brazil

Agroforestry systems are indicated as an alternative for sugarcane (Saccharum officinarum) cultivation in Piracicaba, SP, Brazil, however there are not many field experiments on plant performance under these conditions in the world. The objective of this work was to assess crop yield and partitioning in a sugarcane-rubber (Hevea brasiliensis) interface in on-farm conditions. The availability of irradiance for the crop along the interface was simulated and its effe ct over sugarcane dry matter production was tested. Crop yield was negatively affected by distance of the trees, but development and sucrose were not affected. Above ground dry matter increased from 16.6 to 51.5 t ha-1 from trees. Partitioning did not have a defined standard, as harvest index increased from 0.85 to 0.93, but specific leaf area was not significant along the transect, ranging from 13.48 to 15.73 m² kg-1. Light is the main factor of competition between the trees and the crop, but the relative importance of below ground interactions increases closer to the trees. Feasibility of the system depends on maturity of the trees and management strategies.

Euschistus heros mass rearing technique for the multiplication of Telenomus podisi

The objective of this work was to improve the mass rearing technique of Euschistus heros in laboratory. Nymphs and adults were reared at densities 100, 200, 300 and 400 eggs per Petri dish (9 cm diameter), and at 50, 100, 150 and 200 couples per rearing cages (900 mL), respectively. Survival rate of immature stages and survivorship and reproduction of adults were determinated. Survivorship of nymph to adult was the highest (89%) at density 100 eggs per dish. Adult survivorship was independent of density, and 100 couples per cage were the best to improve quality of the produced progeny. In these conditions, fecundity was 160.8±9.28 eggs per female, and a total of 8,950±456 eggs per cage per month was produced. Two hundred couples per cage showed a negative effect on reproduction, which decreased to 65%. With this technique, a colony of 35 cages with 100 couples per cage yields about 313.3 thousands eggs per month, which is enough to supply the egg parasitoid Telenomus podisi to colonize about 35 ha of soybean field.

Is tagging with visual implant elastomer a reliable technique for marking earthworms?

Visual implant elastomer (VIE) has recently been employed to investigate different aspects of earthworm ecology. However, a number of fundamental questions relating to the detection and positioning of the tag, its persistence and potential effects on earthworms remain unknown. Seven earthworm species belonging to three ecological groupings, with different pigmentation and burrowing behaviour, were tagged using different coloured VIE. External inspection after two days, one week and 1, 10 and 27 months were followed by preservation, dissection and internal inspection. Tags could be seen in living specimens to 27 months, and dissection revealed that in most cases they were lodged in the coelomic cavity, held in place by septa. However, over longer time periods (more than two years), the chlorogogenous tissue tended to bind to the tags and made external observation increasingly difficult. Migration of the VIE material towards the posterior of the earthworm and potential loss of the tag were only observed on rare occasions, and a recovery rate in excess of 98% was recorded. By introducing a reasonable amount of VIE into segments, just after the clitellum, this technique can become a valuable tool in earthworm ecology and life history studies, particularly in short-medium term laboratory and field experiments.

Step-by-step of ultrasound-guided core-needle biopsy of the breast: review and technique

Ultrasound-guided core-needle biopsy has high sensitivity in the diagnosis of breast cancer. The present study is aimed at detailing the main steps of such procedure, including indications, advantages, limitations, follow-up and description of the technique, besides presenting a checklist including the critical steps required for an appropriate practice of the technique. In the recent years, an increasing number of patients have required breast biopsy, indicating the necessity of a proportional increase in the number of skilled professionals to carry out the procedures and histological diagnoses. A multidisciplinary approach involving the tripod clinical practice-radiology-pathology is responsible for the highest rate of accuracy of the technique and must always be adopted.

Técnicas in situ de baixo custo em eletroquímica: a microbalança a cristal de quartzo

Among in situ techniques, the electrochemical quartz crystal microbalance (EQCM) is a powerful tool for the study of electrochemical reactions that produce mass changes in the electrode/solution interface. This review present some systems in which the EQCM combined with classical electrochemical techniques, gives relevant information for understanding the charge transport process at a molecular level. The aim of this review is to do a brief description of experimental arrangements, with emphasis on some special cares that must be considered by the users. Secondly, some chosen electrochemical systems where the technique was successfully applied are discussed. Finally, a brief analysis of electroacoustic impedance experiments was done in order to show when the Sauerbrey equation can be used.

Use of the EPR technique to determine thermal stability of some humified organic substances found in soil organic-mineral fractions

In this work, using the EPR spectroscopy, we analysed the thermal stability of some organic-mineral compounds found in a Gleysoil from Rio Janeiro. It was observed a complete disappearance of the EPR signal around 600 °C for the < 2 µm fraction and a residual EPR signal of semiquinone free radical for the 2-20 µm and 20-53 µm fractions at the same temperature. Also, the experiments showed that the 2-20 µm fraction had a larger concentration of semiquinone free radical per g of carbon and a smaller line width indicated a larger humification of this fraction. This is an evidence that the soil organic matter of this fraction (2-20 µm) is more stable than the other ones.

Uma interface lab-made para aquisição de sinais analógicos instrumentais via porta paralela do microcomputador

A lab-made interface for acquisition of instrumental analog signals between 0 and 5 V at a frequency up to 670 kHz at the parallel port of a microcomputer is described. Since it uses few and small components, it was built into the connector of a printer parallel cable. Its performance was evaluated by monitoring the signals of four different instruments and similar analytical curves were obtained with the interface and from readings from the instrument' displays. Because the components are cheap (~U$35,00) and easy to get, the proposed interface is a simple and economical alternative for data acquisition in small laboratories for routine work, research and teaching.

Construção e avaliação de célula de fluxo para estudo da tensão interfacial dinâmica da interface fluxo líquido - sólido por despolarização da fluorescência

A simple low-cost flow cell was developed, built and optimized in order to observe dynamic interfacial tension of continuous flow systems. Distinct materials can be used in one of the cell walls in order to observe the intermolecular forces between the flowing liquid and the chemical constitution of the walls. The fluorescence depolarization was evaluated using Rhodamine B as fluorescent probe seeded in ethylene glycol. The effects of the positioning angles on the data acquired across the cell are reported. The reproducibility of the data was evaluated with a spectrometer assembled in-house and the relative standard deviation was below 3%.

Quantificação de fluxos de mercúrio gasoso na interface solo/atmosfera utilizando câmara de fluxo dinâmica: aplicação na bacia do Rio Negro

Gaseous mercury sampling conditions were optimized and a dynamic flux chamber was used to measure the air/surface exchange of mercury in some areas of the Negro river basin with different vegetal coverings. At the two forest sites (flooding and non-flooding), low mercury fluxes were observed: maximum of 3 pmol m-2 h-1 - day and minimum of -1 pmol m-2 h-1 - night. At the deforested site, the mercury fluxes were higher and always positive: maximum of 26 pmol m-2 h-1 - day and 17 pmol m-2 h-1 - night. Our results showed that deforestation could be responsible for significantly increasing soil Hg emissions, mainly because of the high soil temperatures reached at deforested sites.