256 research outputs found

    Integrated pest management of the Mexican rice borer in Louisiana and Texas sugarcane and rice

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    Interactions between sugarcane, Saccharum spp., and the invasive species Mexican rice borer, Eoreuma loftini (Dyar), were evaluated in field experiments and in the greenhouse with rice, Oryza sativa L., as an additional host. By determining adult emergence holes together with percent bored internodes, a novel method for evaluating sugarcane cultivar resistance was developed. In 2001, LCP 85-384 had the greatest moth production per hectare, significantly higher (P ≤ 0.05) than HoCP 85-845. High levels of sodium and magnesium salt stress in the soil were associated with higher E. loftini injury in all cultivars except HoCP 91-555 and CP 70-321. Irrigation reduced injury in both susceptible (LCP 85-384) and resistant (HoCP 85-845) cultivars by 2.5-fold. The combination of irrigation, plant resistance, and insecticide applications of tebufenozide decreased injury from 70% bored internodes to less than 10%. Several free amino acids essential for insect development increased in sugarcane leaves under drought stressed conditions, which exacerbated E. loftini infestations. Drought stressed sugarcane was 1.8-fold more attractive based on egg masses/plant than non stressed sugarcane. Based on egg masses/plant and eggs/egg mass, cultivar LCP 85-384 was more attractive than the resistant HoCP 85-845. Egg masses were 9.2-fold more abundant on sugarcane than on rice. Oviposition on sugarcane occurred exclusively on dry leaf material, and the number of dry leaves was positively correlated with egg masses per plant. Several free amino acids essential for insect development increased in sugarcane leaves under drought stressed conditions, and were highly correlated with egg masses per plant. Rice leaves, despite being less attractive for oviposition, had higher levels of free amino acids than sugarcane. Based on boundary movement monitoring with pheromone traps, the average rate of spread from 1980 (Weslaco, TX) to 2004 (Chambers County, TX) was 23.2 km/yr. From 2000 to 2004, annual mean centroids of moth trap counts moved 29.3 km, however 95% C.I. overlapped across years. Minimizing sugarcane stress will play a major role in managing this invasive pest when it becomes established in Louisiana

    <sup>15</sup>N-amino sugar stable isotope probing (<sup>15</sup>N-SIP) to trace the assimilation of fertiliser-N by soil bacterial and fungal communities

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    Although amino sugars represent a major component of soil organic nitrogen (ON), the assimilation of nitrate (NO3−) and ammonium (NH4+) into amino sugars (AS) by soil bacteria and fungi represents a neglected aspect of the global N cycle. A deeper knowledge of AS responses to N fertiliser addition may help enhance N use efficiency (NUE) within agricultural systems. Our aim was to extend a sensitive compound-specific 15N-stable isotope probing (SIP) approach developed for amino acids (AAs) to investigate the immobilization of inorganic N into a range of amino sugars (muramic acid, glucosamine, galactosamine, mannosamine). Laboratory incubations using 15N-ammonium and 15N-nitrate applied at agriculturally relevant rates (190 and 100 kg N ha−1 for 15NH4+ and 15NO3−, respectively) were carried out to obtain quantitative measures of N-assimilation into the AS pool of a grassland soil over a 32-d period. Using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) we found that δ15N values for individual AS reflected differences in routing of the applied ammonium and nitrate. The contrasting N-assimilation dynamics of bacterial and fungal communities were demonstrated through determinations of percentage 15N incorporation into diagnostic AS. N-assimilation dynamics of the bacterial community were altered with the applied substrate whilst fungal N-assimilation dynamics were unaffected. Rates and fluxes of the applied N-substrates into the bacterial AS pool reflected known biosynthetic pathways for AS, with fungal glucosamine appearing to be biosynthetically further from the applied substrates than bacterial glucosamine due to different turnover rates. This sensitive and specific compound specific 15N-SIP approach using AS, building on existing approaches with AAs, enables differentiation of N assimilation dynamics within the microbial community and assessment of microbial NUE with agriculturally relevant fertilisation rates

    The invasive kudzu bug, Megacopta cribraria (Hemiptera: Plataspidae) as an agricultural and nuisance pest

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    The invasive “kudzu bug,” Megacopta cribraria (Hemiptera: Plataspidae) is a native of Asia that was found in northeastern Georgia in fall 2009. This insect has since spread rapidly throughout the southeastern U.S., and is abundant in much of South Carolina. Megacopta cribraria feed on the vascular fluid of several legumes, primarily kudzu, Puereria montana var. lobata, and soybeans, Glycine max. These insects enter soybean fields in often alarming numbers, leaving conspicuous lesions on soybean stems and potentially reducing yields. In addition, M. cribraria congregate on homes and other structures in late fall as they seek overwintering sites, potentially becoming a nuisance pest where populations are large. We examined M. cribraria as a yield reducing pest of soybeans and as a nuisance pest of buildings. Large populations of M. cribraria in caged soybean plots resulted in yield losses of up to 59.6%, and yield reductions were similar in both 2011 and 2012. Several professional-use insecticides were effective in controlling M. cribraria on a variety of building material surfaces, and in some insecticide × surface combinations activity was maintained 30 days post-application. These results contribute to our still developing understanding of this insect as an agricultural and nuisance pest

    Cerebral blood flow and behavioural effects of caffeine in habitual and non-habitual consumers of caffeine: A near infrared spectroscopy study

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    Caffeine has been shown to modulate cerebral blood flow, with little evidence of tolerance to these effects following habitual use. However, previous studies have focused on caffeine levels much higher than those found in dietary servings and have compared high caffeine consumers with low consumers rather than 'non-consumers'. The current placebo-controlled double-blind, balanced-crossover study employed near infrared spectroscopy to monitor pre-frontal cerebral-haemodynamics at rest and during completion of tasks that activate the pre-frontal cortex. Twenty healthy young habitual and non-habitual consumers of caffeine received 75mg caffeine or placebo. Caffeine significantly decreased cerebral blood flow but this was subject to a significant interaction with consumption status, with no significant effect being shown in habitual consumers and an exaggerated effect in non-habitual consumers. These findings suggest that caffeine, at levels typically found in a single dietary serving, is able to modulate cerebral blood flow but these effects are subject to tolerance

    Sugarcane stem borers of the Colombian Cauca River Valley: current pest status, biology, and control

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    Citation: Vargas, G., Gomez, L. A., & Michaud, J. P. (2015). Sugarcane stem borers of the Colombian Cauca River Valley: current pest status, biology, and control. Florida Entomologist, 98(2), 728-735. Retrieved from ://WOS:000356451400049Sugarcane stem borers of the genus of Diatraea (Lepidoptera: Crambidae) form a species complex that causes serious economic losses to sugarcane production in the Cauca River Valley and other regions of Colombia. Two primary species, Diatraea saccharalis (F.) and D. indigenella Dyar and Heinrich, have been effectively managed for more than 4 decades through augmentative releases of the tachinid flies Lydella minense (Townsend) and Billaea claripalpis (Wulp) (Diptera: Tachinidae) and the egg parasitoid Trichogramma exiguum Pinto & Platner (Hymenoptera: Trichogrammatidae). Here we review the current pest status of Diatraea species, damage assessment protocols, management tactics, and the environmental factors and cultural practices that can affect biological control outcomes. Recent changes in the cultivars grown have the potential to increase pest populations and diminish biological control efficacy. Additionally, recent outbreaks of new Diatraea species may further increase overall pest pressure. Thus, there is a need to develop supplementary tactics for the management of these pests that will be compatible with biological control, as well as more reliable protocols for assessing host plant resistance against the increase in infestation intensity

    Ethical and methodological issues in engaging young people living in poverty with participatory research methods

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    This paper discusses the methodological and ethical issues arising from a project that focused on conducting a qualitative study using participatory techniques with children and young people living in disadvantage. The main aim of the study was to explore the impact of poverty on children and young people's access to public and private services. The paper is based on the author's perspective of the first stage of the fieldwork from the project. It discusses the ethical implications of involving children and young people in the research process, in particular issues relating to access and recruitment, the role of young people's advisory groups, use of visual data and collection of data in young people's homes. The paper also identifies some strategies for addressing the difficulties encountered in relation to each of these aspects and it considers the benefits of adopting participatory methods when conducting research with children and young people

    La estrategia Educativa 2020 o las limitaciones del Banco Mundial para promover el "aprendizaje para todos"

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    La nueva Estrategia Educativa 2020 del Banco Mundial establece las prioridades de reforma educativa en paises en vias de desarrollo para la decada siguiente. El titulo explicito de la estrategia, Aprendizaje para Todos, es un claro reconocimiento de que, mas alla de politicas centradas en el acceso, se debe hacer algo mas para asegurar que la educacion derive en experiencias positivas de aprendizaje. Sin embargo, como este articulo sostiene, las opciones de politicas explicitas y latentes en la Estrategia 2020 no son las mas adecuadas para lograr el Aprendizaje para Todos. El articulo desarrolla tres tipos de argumentos al respecto. El primero se refiere al fuerte apego del Banco a un conocimiento disciplinario y un enfoque metodológico que es insufi ciente para entender lo que aprenden los niños en la escuela y por que. El segundo argumento se refiere al sesgo pro-mercado de la Estrategia por lo que respecta a la reforma del sector publico y a nuevas formas de oferta educativa. En tercer lugar, el articulo senala las principales ausencias de la Estrategia, con especial atencion a las omisiones relacionadas con la compleja relación entre educación y pobreza.The World Bank's 2020 Education Strategy establishes the new education priorities in developing countries for the next decade. Its title, Learning for All, clearly recognizes that, beyond policies focusing on access, something else must be done to ensure that schooling involves positive learning experiences. However, as this paper argues, the 2020 Strategy explicit and latent policy options might not be adequate to achieve Learning for All. This paper develops three arguments on that matter. The fi rst one refers to the Bank's strong attachment to a disciplinary knowledge and a methodological approach that do not suffi ce to understand what children learn at school and why. The second one addresses its pro-market bias when it approaches the public sector reforms and the new forms of providing education. The last argument points out the main omissions of this Strategy, especially in what regards the complex relation between education and poverty

    Spin Correlation in tt-bar Production from pp-bar Collisions at sqrt(s)=1.8 TeV

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    The D0 collaboration has performed a study of spin correlation in tt-bar production for the process tt-bar to bb-bar W^+W^-, where the W bosons decay to e-nu or mu-nu. A sample of six events was collected during an exposure of the D0 detector to an integrated luminosity of approximately 125 pb^-1 of sqrt{s}=1.8 TeV pp-bar collisions. The standard model (SM) predicts that the short lifetime of the top quark ensures the transmission of any spin information at production to the tt-bar decay products. The degree of spin correlation is characterized by a correlation coefficient k. We find that k>-0.25 at the 68% confidence level, in agreement with the SM prediction of k=0.88.Comment: Submitted to PRL, Added references, minor changes to tex

    A measurement of the W boson mass using large rapidity electrons

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    We present a measurement of the W boson mass using data collected by the D0 experiment at the Fermilab Tevatron during 1994--1995. We identify W bosons by their decays to e-nu final states where the electron is detected in a forward calorimeter. We extract the W boson mass, Mw, by fitting the transverse mass and transverse electron and neutrino momentum spectra from a sample of 11,089 W -> e nu decay candidates. We use a sample of 1,687 dielectron events, mostly due to Z -> ee decays, to constrain our model of the detector response. Using the forward calorimeter data, we measure Mw = 80.691 +- 0.227 GeV. Combining the forward calorimeter measurements with our previously published central calorimeter results, we obtain Mw = 80.482 +- 0.091 GeV

    Direct Search for Charged Higgs Bosons in Decays of Top Quarks

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    We present a search for charged Higgs bosons in decays of pair-produced top quarks in pbar p collisions at sqrt(s) = 1.8 TeV using 62.2 pb^-1 of data recorded by the D0 detector at the Fermilab Tevatron collider. No evidence is found for signal, and we exclude at 95% confidence most regions of the (M higgs, tan beta) parameter space where the decay t->H b has a branching fraction greater than 0.36 and B(H -> tau nu) is large.Comment: 11 pages, 4 figures, submitted to Phys. Rev. Let
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