Hidrogenionic potential (pH) of the attractant, trap density and control threshold for Ceratitis capitata (Diptera: tephritidae) on Hamlin oranges in São Paulo central region, Brazil

This study evaluated the effect of initial pH values of 4.5, 6.5 and 8.5 of the attractant (protein bait) Milhocina® and borax (sodium borate) in the feld, on the capture of fruit flies in McPhail traps, using 1, 2, 4 and 8 traps per hectare, in order to estimate control thresholds in a Hamlin orange grove in the central region of the state of São Paulo. The most abundant fruit fly species was Ceratitis capitata, comprising almost 99% of the fruit flies captured, of which 80% were females. The largest captures of C. capitata were found in traps baited with Milhocina® and borax at pH 8.5. Captures per trap for the four densities were similar, indicating that the population can be estimated with one trap per hectare in areas with high populations. It was found positive relationships between captures of C. capitata and the number of Hamlin oranges damaged, 2 and 3 weeks after capture. It was obtained equations that correlate captures and damage levels which can be used to estimate control thresholds. The average loss caused in Hamlin orange fruits by C. capitata was 2.5 tons per hectare or 7.5% of production.Esta pesquisa teve como objetivos: avaliar o efeito do pH inicial, 4.5; 6.5 e 8.5, do atrativo proteico Milhocina® e bórax (tetraborato de sódio) na captura de moscas-das-frutas em armadilhas McPhail; estudar densidades de armadilhas, 1; 2; 4 e 8 por hectare, para estimar níveis de controle em laranja cv. Hamlin, na região central de São Paulo. A espécie predominante, com 99% das moscas-das-frutas capturadas, foi Ceratitis capitata, sendo 80% de fêmeas. As maiores capturas de C. capitata ocorreram nas armadilhas com Milhocina® e bórax em pH 8.5. As capturas, nas 4 densidades, foram semelhantes, indicando que a população pode ser estimada com uma armadilha por hectare em áreas de altas populações. Houve relações positivas entre capturas de C. capitata e o número de frutos danificados, 2 e 3 semanas após a captura. Assim, foram obtidas equações que relacionam a captura e o dano, possibilitando estimar níveis de controle desse inseto. As perdas médias causadas por C. capitata em laranja cv. Hamlin chegaram a 2,5 toneladas de frutos por hectare ou 7,5% da produção.info:eu-repo/semantics/publishedVersio

Informational Efficiency in Futures Markets for Crude Oil

This paper develops a methodology to test whether recent developments on world oil markets are in line with the hypothesis of efficient markets. We treat the joint hypothesis problem as stated by Fama (1970), Fama (1991), that market efficiency can only be assessed in conjunction with a price model of market equilibrium. Data on spot and futures prices for Brent crude oil in the period 2002-2008 are used in combination with a multi factor model to investigate whether futures prices are efficient forecasts of future spot prices. The hypothesis of market efficiency is assessed by comparing the observed developments of crude oil spot prices to the ex-ante expected distributions of spot prices using the Rosenblatt transform. For the Brent crude oil futures market, the results are in line with the hypothesis of market efficiency in the short-term but during our sample period the hypothesis is refuted when forecast horizons of one year are considered. Our findings suggest that it can lead to rather wrong investment decisions when relying on longer-term crude oil futures prices and the information contained therein

Trends, Persistence, and Volatility in Energy Markets

This paper makes a threefold contribution to the underlying dynamic properties and causal effects of energy prices. Firstly, the paper makes a study of the underlying trends to help identify the time series path of nonrenewable energy resources, which can have far reaching consequences for economists and policy makers alike. The analysis is extended to also determine the persistence of oil price shocks. Secondly, the study examines the causal relation between oil prices and the macroeconomy allowing for nonlinear models that have been recently advocated in the literature. Finally, this study describes the relation between oil prices and agricultural commodities. From a policy perspective, these interrelationships of agricultural and oil prices warrant careful consideration in the context of the recent energy crisis, which may very well continue in the future