Lewis through a looking glass : public sector employment, rent-seeking, and economic growth

This paper argues that the labor transfer process outlined by the Lewis model (1954) can give rise to surplus labour - in the sense than the marginal product of labour is less that the wage - in the public part of the modern sector and that this may deprive the modern sector of its dynamism. Moreover, creating sheltered employment tends to be self-perpetuating. It creates and consolidates vested interests that seek to perpetuate the protected jobs. In the inverse of the Lewis model, the extent of surplus labour increases, rather than diminishes, over time.Environmental Economics&Policies,Banks&Banking Reform,Economic Theory&Research,Public Sector Economics&Finance,Health Monitoring&Evaluation

Insect pest and natural enemy populations in paired organic and conventional apple orchards in the Yakima Valley, Washington

Insect pest and natural enemy populations were evaluated during the 1990 growing season in five paired certified organic and conventional apple orchards in the Yakima Valley, Washington. Each orchard pair was managed by one grower and had similar conditions of location, extent, cultivars, and tree density. Organic orchards had not been treated with synthetic insecticides for 1-2 years before this study. Fruit injury from codling moth and population densities of phytophagous mites, sucking bugs, rosy apple and green aphids, leafminers, leafhoppers, and selected natural enemies were monitored throughout the season. Damage from codling moth was over 3% in three of the five organic orchards. Densities of phytophagous mites were high in one conventional orchard at the end of the season. Organic orchards had significantly higher populations of sucking bugs at bloom than did conventional orchards. There was no significant difference between orchard types in the densities of rosy apple aphid colonies per tree, but colonies in conventional orchards had significantly more aphids and significantly less parasitism than in organic orchards. The population density of green aphids was higher in conventional than organic orchards during the second half of the season. There was little difference in numbers of adult leafhoppers caught on sticky traps between orchard types, but captures of a leafhopper egg parasite were significantly higher in organic than in conventional orchards throughout the season. Immature leafminer populations were significantly higher and parasitism of leaf miner was significantly lower in conventional than organic orchards after July. Parasitism of codling moth was not found in any orchard.Key words: Codling moth; organic; apple; pest management; aphid; mite; leafhopper; leafminer; egg parasit

Combining mutualistic yeast and pathogenic virus - a novel method for codling moth control

The combination of a pathogenic virus and mutualistic yeasts isolated from larvae of codling moth Cydia pomonella is proposed as a novel insect control technique. Apples were treated with codling moth granulovirus (CpGV) and either one of three yeasts, Metschnikowia pulcherrima, Cryptococcus tephrensis, or Aureobasidium pullulans. The combination of yeasts with CpGV significantly increased mortality of neonate codling moth larvae, compared with CpGV alone. The three yeasts were equally efficient in enhancing the activity of CpGV. The addition of brown cane sugar to yeast further increased larval mortality and the protection of fruit against larvae. In comparison, without yeast, the addition of sugar to CpGV did not produce a significant effect. A field trial confirmed that fruit injury and larval survival were significantly reduced when apple trees were sprayed with CpGV, M. pulcherrima, and sugar. We have shown earlier that mutualistic yeasts are an essential part of codling moth larval diet. The finding that yeast also enhances larval ingestion of an insect-pathogenic virus is an opportunity for the development of a novel plant protection technique. We expect the combination of yeasts and insect pathogens to essentially contribute to future insect management

Testing an attracticide hollow fibre formulation for control of Codling Moth, Cydia pomonella (Lepidoptera: Tortricidae)

Laboratory and field tests were conducted to evaluate the use of an experimental sprayable formulation of chopped hollow fibres loaded with codlemone and mixed with 1.0% esfenvalerate and an adhesive to control codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae). Moths were not repelled by the addition of the insecticide to the adhesive and were rapidly killed following brief contact. A significantly greater proportion of male moths flew upwind and contacted individual fibres for a longer period of time when fibres had been aged > 7 d versus fibres 0 – 7 days-old in flight tunnel tests. Field tests using sentinel fibres placed in 10.0 mg drops of adhesive on plastic disks stapled to the tree found that fibres were not touched until they had aged > 8 d. Conversely, moth mortality following a 3-s exposure to field-collected fibres deposited on the top of leaves was low in bioassays with fibres aged > 8 d. The deposition and adhesion of fibres within the apple canopy appear to be two major factors influencing the success of this approach. Fibres were found adhering to foliage, fruit, and bark within the orchard; however, visual recovery of fibres following each of the three applications was < 5.0%. Both the substrate and the positioning of the fibre on the substrate influenced fibre retention. The highest proportion of fibres was found initially on the upper surface of leaves and this position also had the highest level of fibre retention. Fibres on the underside of leaves or partially hanging off of a substrate were dislodged within two weeks

Structure/function relationships in the inhibition of thimet oligopeptidase by carboxyphenylpropyl-peptides

AbstractSome novel N-[1(RS)-carboxy-3-phenylpropyl]tripeptide p-aminobenzoates have been synthesised as inhibitors of thimet oligopeptidase (EC 3.4.24.15). These compounds are considered to bind as substrate analogues with the Cpp group in S1 and the peptide portion in the S′ sites. The most potent inhibitor is Cpp-Ala-Pro-Phe-pAb, which has a K1 = 7 nM. Substitution of Gly for Ala at P1′ leads to weaker binding which can be ascribed to increased rotational freedom. Good substrates often have Pro at P2′ and Pro is favoured over Ala at this position in the inhibitors, too. When P2′ is Pro, Phe is preferred over Tyr and Trp in P3′. The p-aminobenzoate group makes an important contribution to the binding, probably by forming a salt bridge, and removal of the C-terminal negative charge results in much less potent inhibitors

Oviposition and Calling Behavior of Codling Moth (Lepidoptera: Tortricidae) in the Presence of Codlemone

The effect of the major component of codling moth, Cydia pomonella (L.) sex pheromone (codlemone, E,E-8,10-dodecadien-l-ol) on female calling and oviposition behavior was investigated. Calling by virgin females was similar between moths placed in sealed containers containing codlemone or codlemone-free air. However, when pheromone emitted by females was removed by a continuous air stream, calling in codlemone-permeated air was significantly higher than in clean air. The temporal pattern of calling was unaltered by the presence of codlemone. In a laboratory no-choice test, oviposition rates by codling moth females were similar in the presence of codlemone and in codlemone-free air. However, in paired-choice tests, females deposited more eggs on uncontaminated waxed paper surfaces than on codlemone-contaminated surfaces

How Agricultural Economists Increase the Value of Agribusiness Research

Historically, there has been declining cooperation between agribusiness firms and agricultural economists. In new product marketing research, firms' tend to conduct their own analyses, partially due to confidentiality, usually consisting of simple univariate or bivariate statistics such as chi-squared tests of independence. The primary objective of this paper is to demonstrate, through a case study, one way in which agricultural economists can add value to agribusiness firms research. Results from the econometric model offer a richer explanation of consumer behavior and may be more useful to agribusiness firms.Teaching/Communication/Extension/Profession,

Influence of Trap Colour on the Capture of Codling Moth (Lepidoptera: Tortricidae), Honeybees, and Non-target Flies

Studies were conducted to evaluate the influence of trap colour on the captures of honeybees, Apis mellifera L., codling moth, Cydia pomonella L., and non target muscoid flies in sticky delta traps. Traps varied widely in their spectral reflectance. The unpainted white and the painted white and cream traps had the highest reflectance. The painted green trap had the lowest total reflectance. The green, orange, and red traps had low reflectance at wavelengths < 560 nm. Red and green painted traps consistently caught the fewest honeybees, while the unpainted white trap caught the most. Red painted traps caught the greatest number of flies. Significantly more codling moths were caught in green and orange versus the unpainted white traps. In a later experiment, painted green traps caught more codling moths than unpainted white traps

Optimal Control of Spreading Biological Invasions: For How Long Should We Apply the Brake?

Identifying the optimal switching point between different invasive alien species (IAS) management policies is a very complex task and policy makers are in need of modelling tools to assist them. In this paper we develop an optimal control bioeconomic model to estimate the type of optimal policy and switching point of control efforts against a spreading IAS. We apply the models to the case study of Colorado potato beetle in the UK. The results demonstrate that eradication is optimal for small initial sizes of invasion at discovery. High capacity of the agency to reduce spread velocity for several years leads to smaller total overall costs of invasion and makes eradication optimal for larger sizes of initial invasion. In many cases, it is optimal to switch from control to acceptance within the time horizon. The switching point depends on the capacity of the agency, initial size of invasion, spread velocity of the IAS and the ratio of unit cost of damage and removal. We encourage the integration of the dispersal patterns of the invader and the geometry of the invasion in the theoretical development of the economics of IAS invasion management.barrier zone, biosecurity, dynamic optimization, eradication, Leptinotarsa decemlineata, pest risk analysis, reaction-diffusion., Risk and Uncertainty, Q1, Q28, Q57,

THE ECONOMIC FACTORS INFLUENCING PRODUCERS' DEMAND FOR FARM MANAGERS

Results from a Tobit model showed a complementary relationship between marketing inputs and the decision to hire farm managers. According to the results, as farmers increase expenditure on marketing consultants and information systems, their expenditure on farm managers increase as well.Farm Management,