Efeito da umidade do solo na biologia de Rhopalosiphum maidis (FITCH, 1856) (Hemiptera: aphididae) em milho.

O efeito da umidade do solo na biologia de Rhopalosiphum maidis (Fitch) em plantas de milho (Zea mays) foi avaliado em casa de vegetação. Foi utilizado o delineamento experimental inteiramente casualizado, com três tratamentos (20%, 40% e 100% de rotação hídrica) e quatro repetições, sendo cada parcela experimental constituída por um vaso de polietileno de cinco litros contendo duas plantas de milho no estádio fenológico três e com dez pulgões adultos confinados em microgaiolas de 10 mm de altura por 10 mm de diâmetro (cinco pulgões/microgaiola/planta), perfazendo um total de 40 pulgões/tratamento. As variáveis biológicas do pulgão estudadas foram: a duração de cada instar, dos períodos pré-reprodutivo, pós-reprodutivo e reprodutivo, a produção diária, total de ninfas e de alados e o ciclo de vida de R. maidis. Houve efeito da umidade do solo onde estavam as plantas de milho, tanto na duração do desenvolvimento dos pulgões, em cada um dos quatro ínstares, quanto na duração da fase ninfal, sendo que os pulgões que se desenvolveram em plantas de milho com défice de água de 80% completaram os estádios ninfais num menor período. De igual forma, o período reprodutivo e a longevidade dos adultos foram mais curtos nos pulgões que se desenvolveram em plantas de milho em solo com 20% da capacidade de campo. Porém, não houve efeito dos tratamentos na duração do período pós-reprodutivo. Por outro lado, adultos de pulgões que se desenvolveram nas plantas em solo com 20% da água necessária produziram a primeira ninfa num menor período do que os desenvolvidos nas plantas que receberam 40% de água na capacidade de campo. Pulgões cuja fase jovem ocorreu em plantas de milho sob estresse hídrico de 80% desapareceram mais rapidamente do que aqueles desenvolvidos em plantas sob regime de estresse hídrico de 60%. Esses resultados indicam que o manejo da água no milho pode ser uma estratégia no controle de fatores naturais que afetam tanto a população como o número de gerações do pulgão no ambiente, podendo reduzir a necessidade do controle químico

A importância da meso e macrofauna do solo na fertilidade e como bioindicadores.

Made available in DSpace on 2011-06-06T17:15:31Z (GMT). No. of bitstreams: 1 aimportanciadamesoemacrofaunadosolo.pdf: 438843 bytes, checksum: 8c3a7d588fad2f7d7f84dd3352828641 (MD5) Previous issue date: 2009-09-2

An Investigation of the KFK_{F}-type Lorentz-Symmetry Breaking Gauge Models in N=1N=1-Supersymmetric Scenario

In this work, we present two possible venues to accomodate the $K_{F}$-type Lorentz-symmetry violating Electrodynamics in an $N=1$-supersymmetric framework. A chiral and a vector superfield are chosen to describe the background that signals Lorentz-symmetry breaking. In each case, the $\ K_{\mu \nu \kappa \lambda }$-tensor is expressed in terms of the components of the background superfield that we choose to describe the breaking. We also present in detail the actions with all fermionic partners of the background that determine $\ K_{\mu \nu \kappa \lambda }$.Comment: 10 page

A social and ecological assessment of tropical land uses at multiple scales: the Sustainable amazon network

Science has a critical role to play in guiding more sustainable development trajectories. Here, we present the Sustainable Amazon Network (Rede Amazônia Sustentável, RAS): a multidisciplinary research initiative involving more than 30 partner organizations working to assess both social and ecological dimensions of land-use sustainability in eastern Brazilian Amazonia. The research approach adopted by RAS offers three advantages for addressing land-use sustainability problems: (i) the collection of synchronized and co-located ecological and socioeconomic data across broad gradients of past and present human use; (ii) a nested sampling design to aid comparison of ecological and socioeconomic conditions associated with different land uses across local, landscape and regional scales; and (iii) a strong engagement with a wide variety of actors and non-research institutions. Here, we elaborate on these key features, and identify the ways in which RAS can help in highlighting those problems in most urgent need of attention, and in guiding improvements in land-use sustainability in Amazonia and elsewhere in the tropics. We also discuss some of the practical lessons, limitations and realities faced during the development of the RAS initiative so far

Linking land-use and land-cover transitions to their ecological impact in the Amazon.

Human activities pose a major threat to tropical forest biodiversity and ecosystem serv-ices. Although the impacts of deforestation are well studied, multiple land-use andland-cover transitions (LULCTs) occur in tropical landscapes, and we do not knowhow LULCTs differ in their rates or impacts on key ecosystem components. Here, wequantified the impacts of 18 LULCTs on three ecosystem components (biodiversity,carbon, and soil), based on 18 variables collected from 310 sites in the BrazilianAmazon. Across all LULCTs, biodiversity was the most affected ecosystem component,followed by carbon stocks, but the magnitude of change differed widely amongLULCTs and individual variables. Forest clearance for pasture was the most prevalentand high-impact transition, but we also identified other LULCTs with high impact butlower prevalence (e.g., forest to agriculture). Our study demonstrates the importanceof considering multiple ecosystem components and LULCTs to understand the conse-quences of human activities in tropical landscape

Twelve-Month Follow-Up of Dexamethasone Implants for Macular Edema from Various Diseases in Vitrectomized and Nonvitrectomized Eyes

Purpose. To evaluate the best-corrected visual acuity (BCVA), central retinal thickness (CRT), and the number of dexamethasone implants needed to treat cystoid macular edema (CME) from various etiologies over 12 months in vitrectomized and nonvitrectomized eyes. Methods. This multicenter retrospective cohort study included 112 patients with CME secondary to retinal diseases treated pro re nata (PRN) with a 0.7 mg intravitreal dexamethasone implant for 12 months. The BCVA, CRT, adverse events, safety data, and number of implants were recorded. Results. Vitrectomized and nonvitrectomized eyes received means of three implants and one implant, respectively, over 12 months (P<0.001). The mean BCVA of all patients improved from 0.13 at baseline to 0.33 (P<0.001) 12 months after one (P=0.001), two (P=0.041), and three (P<0.001) implants but not four implants (P=0.068). The mean baseline CRT decreased significantly (P<0.001) from 463 to 254 microns after 12 months with one (P<0.001), two (P=0.002), and three (P=0.001) implants but not with four implants (P=0.114). The anatomic and functional outcomes were not significantly different between vitrectomized and nonvitrectomized eyes. Increased IOP was the most common adverse event (23.2%). Conclusions. Dexamethasone implant administered PRN improved VA and decreased CRT in CME, with possible long-term clinically relevant benefits for treating CME from various etiologies. Vitrectomized eyes needed more implants compared with nonvitrectomized eyes