Abstract. The efficacy of natural enemies in controlling pests under field conditions is largely correlated with their capacity to spread within infested crops. In this study the spatial dispersal of the California red scale parasitoid Aphytis melinus DeBach (Hymenoptera: Aphelinidae) was evaluated in the field after augmentative releases. The experiment was conducted in 2007 in six 1-ha plots in a Sicilian citrus orchard under integrated pest management. A total of 180,000 A. melinus adults was released in each of three plots and the other plots were left as untreated control. The flight range of the parasitoid was evaluated, for 35 days after the release, on 16 trees per each plot, located at 20 and 40 m from the central release point using yellow sticky traps activated with Aonidiella aurantii (Maskell) (Hemiptera: Diaspididae) sexual pheromone and by monitoring the percentage parasitism of the scale on fruits and twigs. The effects of the distance from the release point and density of susceptible stages of host on parasitoid dispersal were evaluated. The number of wasps captured during the whole trial was greater in the traps located 20 m from the release point than in those at 40 m and in the control plots. Aphytis melinus dispersed over distances less than 40 m based on both the lower percentage parasitism and numbers captured recorded at distances of 40 m. The results are discussed in the context of the biological control of California red scale in citrus orchards by means of wasp releases. In particular, the release points should be no more than 40 m apart for a quick and homogeneous colonization of the area treated.
This paper argues that the European Union has gone farther than any other country or institution in internalizing the prescriptions of the Washington Consensus. Embedding neo-liberal principles in the treaties defining its governance, the EU has enshrined a peculiar doctrine within its constitution. We further argue that this "Berlin-Washinghton Consensus" has serious empirical and theoretical flaws, as its reliance on Pareto optimality leads to neglect the crucial links between current and potential growth. We show by means of a simple model that the call for structural reforms as an engine for growth may be controversial, once current and potential output are related. We claim that adherence to the Consensus may go a long way in explaining the poor growth performance of the European economy in the past two decades, because of the constraints that it imposed on fiscal and monetary policies. The same constraints have deepened the eurozone crisis that started in 2007, putting unwarranted emphasis on austerity and reform. Challenging the Consensus becomes a precondition for avoiding the implosion of the euro, and recovering growth.
This paper aims at investigating first the (possibly time-varying) empirical relationship between the level and conditional variances of price and financial stability, and second, the effects of macro and policy variables on this relationship in the United States and the Eurozone. Three empirical methods are used to examine the relevance of A.J. Schwartz's "conventional wisdom" that price stability would yield financial stability. Using simple correlations, VAR and Dynamic Conditional Correlations, we reject the hypothesis that price stability is positively correlated to financial stability. We then discuss the empirical appropriateness of the "leaning against the wind" monetary policy approach.
Keynes' main concern in the General Theory is about the capacity of an economy to return to full employment equilibrium when subject to a (negative) demand shock. He maintains that money wages cuts may not help reabsorb unemployment, as they do not necessarily imply a fall in real wages. On the contrary, wage rigidity may be necessary for avoiding that a cumulative process propels the economy far away the full employment equilibrium. Co-ordination failures in the investment-saving market are behind this conclusion. However, the analysis is carried out within a static equilibrium framework. This paper is an attempt to focus on the problems of intertemporal co-ordination arising within the context of a sequential economy. Our analysis of the out-of-equilibrium process of adjustment stirred by a shock allows to generalize the original Keynesian intuition. Unemployment emerges as the result of a lack of co-ordination due to irreversibly constrained choices, and not only nominal but also real wage flexibility does not necessarily help to restore equilibrium. As a matter of fact, it may even be harmful, by triggering processes that make the economy diverge from equilibrium. Our analysis has important analytical implications as regards the role of market imperfections and the interpretation of the effects of monetary policy.
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