Serological Identification of Virus in Watermelon Production Fields in the Tocantins State

Watermelon (Citrullus lanatus) cultivated in almost all tropical and subtropical regions of the world, has its largest output in China, and then, according to FAO data, Turkey, Iran and Brazil, being one of the main crops cultivated in State of Tocantins, Brazil. In this work was investigated the occurrence and distribution of the watermelon viruses, totaling 752 samples taken in a stratified experimental design in four representative regions of production: Gurupi (150), Lagoa da Confusao (232), Formoso do Araguaia (265) and Porto Nacional (105). The sampling and collecting the leaves of plants with the presence of symptoms were performed once a week during the entire cultivation cycle. As a result, were observed by Dot-ELISA method, different types of viruses, such as Papaya ringspot W (PRSV-W), Zucchini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV) (potyvirus), Cucumber mosaic virus ( CMV) (Cucumovirus) and Zucchini lethal chlorosis virus (ZLCV) (Tospovirus). Of these, PRSV-W was predominant (22%), followed by WMV (15%), ZLCV (11%), CMV (5%) and ZYMV (4%). Mixed infections with PRSV-W + WMV and PRSV-W + ZLCV were also observed around 20% frequency (expressed with symptoms differently from a single infection). The results provide important support for the program management viruses.

Toxicidade de óleos essenciais de eucalipto e citronela sobre Sitophilus zeamais Motschulsky (Coleoptera: curculionidae) / Toxicity of essential oils of eucalyptus and citronella on Sitophilus zeamais Motschulsky (Coleoptera: curculionidae)

As análises realizadas por cromatografia gasosa acoplada à espectrometria de massas CG/EM apresentou o citronelal como o principal fitoconstituinte dos óleos essenciais de Corymbia citriodora Hill & Johnson, e Cymbopogon nardus (L.), com 61,78 e 36,53%, respectivamente. A toxicidade dos óleos essenciais e do citronelal foi verificada para Sitophilus zeamais por meio das estimativas das curvas de concentrações resposta e tempos de exposição letais para 50 e 95% dos insetos (CL50, CL95, TL50 e TL95). A toxicidade do citronelal foi maior para S. zeamais, com CL50 e CL95 de 0,340 e 0,820µL/cm2 e TL50 e TL95 de 11,89 e 59,50h, respectivamente. A repelência de S. zeamais foi maior para os óleos essenciais de C. nardus e C. citriodora nas concentrações de 0,660; 0,881; 1,101 e 1,321µL/cm2 com 86,6 a 98,8%. O número de insetos emergidos dos grãos pulverizados com os óleos essenciais foi maior para o citronelal nas concentrações de 0,330; 0,440; 0,550, e 0,660µL/cm2 . A redução da massa de grãos foi menor para aqueles grãos tratados com C. citriodora e C. nardus. Óleos essenciais de C. citriodora e C. nardus podem proteger produtos armazenados pelo dano causado por S. zeamais.

Analysis of GC / MS showed citronellal as the main phytochemicals of the essential oils of Corymbia citriodora and Cymbopogon nardus, with 61.78% and 36.53%, respectively. The toxicity of essential oils and citronellal was verified for maize weevils, through the estimates of the concentration response curves and lethal exposure times, for 50% and 95% of the adults insect (LC50, LC95, LT50 and TL95). The toxicity of citronellal was higher for Sitophilus zeamais, with LC50 and LC95 of 0.340 at 0.820 µL/cm2, TL50 and TL95 of 11.89 and 59.50h, respectively. The repellency of S. zeamais was higher for the essential oils of C. nardus and C. citriodora, at concentrations of 1.321, 1.101, 0.881 and 0.660 µL/cm2, ranging from 86.6 to 98.8%. The number of insects emerged from grain sprayed with essential oils was lower for the citronellal, at concentrations of 0.330, 0.440, 0.550, and 0.660 µL/cm2. The reduction in grain weight was lower for those grains, treated with C. citriodora and C. nardus. Essential oils of E. citriodora and C. nardus can protect stored products from damage caused by S. zeamais.

Modelling antagonic effect of lactic acid eacteria supernatants on some pathogenic bacteria

This work presents a statistical model of survival analysis for three pathogenic bacterial strains (Escherichia coli, Listeria monocytogenes and Staphylococcus aureus), when treated with neutralized and non-neutralized filtered supernatants broth from cultures of Lactobacillus acidhophilus, Lactobacillus rhamnosus and Lactobacillus sake. Survival analysis is a method employed to determine the period of time from an initial stage up to the occurrence of a particular event of interest, as death or a particular culture growth failure. In order to evaluate the potential efficacy of the ahead mentioned lactic acid bacteria when used as bioprotective starters in foods, experimental data were statistically treated and expressed by simple representative curves. Following the methodology of Cox and Kaplan-Meier, it was possible to make the selection of the best bioprotective lactic starter, as a predictive tool for evaluation of shelf life and prevention of eventual risks in fresh sausages and other similar food products.

Este trabalho apresenta um modelo estatístico de análise de sobrevivência para três bactérias patogénicas (Escherichia coli, Listeria monocytogenes e Staphylococcus aureus), quando tratados com sobrenadantes filtrados neutralizado e não neutralizado provenientes de culturas de Lactobacillus acidhophilus, Lactobacillus rhamnosus e Lactobacillus sake. A Análise de sobrevivência é um método utilizado para determinar o período de tempo a partir de uma fase inicial até a ocorrência de um determinado evento de interesse, como a morte ou a inibição de uma particular cultura, a fim de avaliar a eficácia potencial das referidas bactérias lácticas quando usadas como bioproteção em alimentos. Os dados experimentais foram tratados estatisticamente, seguindo a metodologia de Cox e Kaplan-Meier e foi possível fazer a seleção dos melhores fermentos láticos bioprotectivos, como uma ferramenta para avaliação preditiva, vida de prateleira e prevenção de eventuais riscos em Lingüiças frescas e outros produtos alimentares.

Utilization of the biorreactor of imersion by bubbles at the micropropagation of Ananas comosus L. Merril

The research for new techniques of in vitro cultivation is being object of many studies around the world, in order to optimize and decrease production costs of seedlings with agronomical interest. The main goal of this work was to compare different systems of in vitro cultivations using Ananas comosus L. Merril. So, the in vitro growth of the plantlets was promoted in two different bioreactors: Bioreactor of Immersion by Bubbles (B.I.B.®) and the Reactor of Temporary Immersion (R.I.T.A.®) with immersion cycle every 2 hours for 15 minutes and the traditional system in flasks with 200 mL. All cultivation systems used the MS liquid nutritive solution, supplemented with BAP (1 mgL-1), ANA (0.25 mgL-1), sucrose (30 gL-1) and Tween 20® (0.5 µL). The pH was adjusted to 5.8 and sterilized at 120°C for 15 minutes. The cultures were kept into a growth room during 30 days, with controlled temperature of 25±2°C, under white cold light (46.8 µmol.m-2.s-1), with photoperiod of 16 hours. The experimental design used was randomized, with three treatments, three repetitions and ten plants each stage. Among the evaluated systems, the BIB® presented the best results for the tested variables, mainly the total number of shoots, being 2.3 e 3.1 times superior when compared with the system R.I.T.A.® and the traditional consecutively. So the system of immersion by bubbles turns into an effective equipment to produce seedlings of pineapple in large scale.

A busca por novas técnicas de cultivo in vitro vem sendo amplamente estudadas, visando otimizar e baixar o custo de produção das mudas que tenham interesse agronômico. O objetivo deste trabalho foi comparar diferentes sistemas de cultivo in vitro de Ananas comosus L. Merril. Para tanto, o crescimento in vitro de plântulas foi promovido em sistemas de biorreatores (B.I.B.® e R.I.T.A.®) com ciclo de imersão a cada 2 horas por 15 minutos e o sistema tradicional em frascos de 200 mL. Em todos os sistemas de cultivo, foram utilizadas solução nutritiva líquida MS, suplementado com 1 mg L-1 de BAP, 0,25 mg L-1 de ANA, 30 g L-1 de sacarose e 0,5 µL de Tween® 20, pH ajustado para 5,8 e autoclavagem a 120°C por 15 minutos. As culturas foram mantidas em sala de crescimento durante 30 dias, temperatura controlada de 25±2°C, sob luz branca fria (46,8 µmol.m-2.s-1), com 16 horas de fotoperíodo. O delineamento foi inteiramente casualizado, com três tratamentos, três repetições e dez plantas por estágios. Para os sistemas avaliados, o biorreator de imersão por bolhas apresentou os melhores resultados dentre as variáveis analisadas, com destaque ao número total de brotações, sendo 2,3 e 3,1 vezes superiores quando comparado com o sistema R.I.T.A.® e sistema tradicional respectivamente. Portanto, o sistema de imersão por bolhas torna-se um equipamento eficaz na produção de mudas de abacaxizeiro em larga escala.