Yield losses due to the natural infestation of fava bean, Vicia faba L., by the leaf miners, Liriomyza spp. in Central Sudan

This study was carried out at the Experimental Farm of the Faculty of Agricultural Sciences, University of Gezira, during the seasons 1996/97 and 1997/98, on two faba bean varieties: Shambat and SML. Two experiments were conducted: one for each variety where two treatments were laid out in a randomized complete block design with six replicates. One treatment was the natural infestation of leaf miners (untreated plots), and the other was protected by the insect growth regulator Trigard 75% wettable powder (treated). In both seasons, the untreated plots were heavily infested by the leaf miners, while the protected plots were lightly infested. Infestation resulted in yield losses of 22.86% and 42.25% for Shambat and 29.16% and 27.64% for SML during the two seasons, respectively. Also, there were highly significant differences (P<0.01) in plant height and number of pods between the treated and the untreated plots. Negative correlations between the percentage of leaf infestation and plant height in the treated plots were detected. (Texte intégral

A comparative study on the life cycles of the leaf miners Liriomyza trifolii (Burgess) and Liriomyza sativae (Blanchard) (Agromyzidae: Diptera)

The life cycles of the leaf miners, Liriomyza trifolii (Burgess) and Liriomyza sativae (Blanchard), were studied in a growth chamber (Temp, 25 ± 1°C; R.H. 75 ± 5%; L/D 12 hL/12 hD and 3000 - 4000 LUX) at CIRAD, Montpellier, France. The host plant used was haricot bean, (Phaseolus vulgaris). The egg incubation period of both species lasted for two days. Highly significant differences (P<0.01) were recorded between the number of feeding punctures caused by L. trifolii and L. sativae. Differences between the larval periods and number of emerging adults were not significant. Upon hatching, during 1996, the number of larvae of L. trifolii was significantly higher than that of L. sativae, but the total life span of L. sativae was significantly longer than that of L. trifolii. (Texte intégral

On Endogenous Growth: The Implications of Environmental Externalities

This paper uses an endogenous growth model to examine the interaction between trade, economic growth, and the environment. We find that whether trade enhances or retards growth depends on the relation between factor intensities of exportable, importable, and R&D and the relative abundance of the factor R&D uses more intensively. Depending on the intertemporal elasticity of substitution, the long-run rate of economic growth changes with environmental externalities. Concerns about the environment can explain a significant part of cross-country difference in growth rates. For the empirically reported range of the elasticity of intertemporal substitution, countries which care more about the environment grow faster. The effects of trade on the environment and welfare depend on the elasticities of supply for the two traded goods, the terms of trade effect on growth, and pollution intensities. The decentralized and Pareto optimal growth rates are, in general, different. The market growth rate is bigger than the optimal rate the larger the degree of monopoly power in the innovation sector and the stronger the effects of environmental externalities. The policy implications of this divergence are discussed. We also consider numerical exercises to broaden the insights from the analytical results and allow for incorporating pollution abatementEnvironmental Economics and Policy, F11, O31, O41, Q20,

Assessment of yield losses due to the natural Infestation of tomato, Lycopersicon esculentum Mill, by the leafminers, Liriomyza spp. in Central Sudan

The leafminer (LM), Liriomyza spp. (Diptera: Agromyzidae) is known to attack tomato crops in the Gezira all year around. The effect of such infestation was not tackled researches in the Sudan. This study was done at the Experimental Farm of the Faculty of Agricultural Sciences, University of Gezira on the tomato variety Peto 86 (season 1996/97) and the breeding line Wad El-Obaid (season 1997/98). One experiment was conducted for each. Two treatments (i.e. insecticide-treated and untreated) were laid out in a RCB design with six replicates. The untreated plots were left to the LMs natural infestation, while the treated plots were protected by the IGR Trigard 75% WP. Highly significant differences (P<0.01) in percentage of leaf infestation were correlated with the highly significant differences in yield between treated and untreated plots. Differences in leaf infestation of ca. 48% in plots of the tomato variety Peto 86 resulted in a yield loss of approximately 44%, compared to 43% loss in yield of Wad El-Obaid, where the percentage of leaf infestation was ca. 56%. Therefore, it is recommended that tomato crop should be treated with insecticides to reduce the effect of the LMs. (Texte intégral

Pathogenesis of Haemorrhagic Septicaemia in Organ Culture, Mice and Calves

Experimental intraperitoneal infection of mice with Pasteurella multocida serotype B:2 at the dose of 107cells caused death in all infected mice between 18 to 24 hours. Microscopy showed suppurative tracheitis. The alveoli lumina were infiltrated with numerous inflammatory cells mainly neutrophils. Pink-stained fibrin and red blood cells were also present in the alveoli lumina. Blue shade of bacterial colonies were observed in the alveolar space and pulmonary vessels. In the aorta, there was degeneration of the endothelium, disruption of the intima and focal myolytic changes in the smooth muscle. In infected mice, scanning electron microcopy (SEM) showed cilial damage and deciliation of tracheal epithelial cells. In the lung extravasation of red blood cells in the alveolar lumina was observed. Rod-shaped bacteria were seen attached to the alveolar wall causing depression on the surfaces of the cells. Changes in the aortas were characterized by rounded endothelial cells. Some rounded endothelial cells were seen about to detach and expelled into the blood vessel lumen. Bacteria were most evident at the intercellular junction of the endothelial cells that were beginning to slough. In infected mice, transmission electron microscopy (TEM) of the trachea showed bacterial cells attached to deformed cilia. Necrotic and apoptotic endothelial cells were seen protruded into the lumen of the affected blood vessel. Several bacteria were attached to the plasma membrane of the endothelial cells and in the blood vessel lumen. Endothelial cells showed electron dense cytoplasmic extensions around the bacteria and as attaching and effacing lesions which were interpreted as the first steps in the phagocytosis process. In the lung, there was thickening of the alveolar septa. Bacteria were seen dividing inside the neutrophils and in the lumen of the blood vessels. Some bacteria were also seen in vacuolated macrophages. Endothelial cells showed apoptosis. Fibrin was present in the alveolar lumina. In the aorta, endothelial cells were fragmented and detached from the basement membranes. Bacteria were attached to the fragmented endothelium. Calves inoculated intranasally with 3.0 x1010 P. multocida serotype B:2 following stressed with dexamethasone developed septicaemia and fibrinous pleuropneumonia. All infected calves died between 24 to 48 hours. Thrombi were observed in the nasal cavity and lung. It is therefore believed that the P. multocida had gained entry into the blood vessel of the nasal cavity and / or lung to various organs causing septicaemia. This is validated by the isolation of pure growth of P. multocida from various congested organs following intranasal infection

Brownian motion of single glycerol molecules in an aqueous solution as studied by dynamic light scattering

Aqueous solutions of glycerol are investigated by dynamic light scattering (DLS) over the whole concentration range (10-98 wt.% water) and in the temperature range 283-303 K. The measurements reveal one slow relaxation process in the geometry of polarized light scattering. This process is present in the whole concentration range, although it is very weak at the highest and lowest water concentrations and is considerably slower than the structural alpha relaxation, which is too fast to be observed on the experimental time scale in the measured temperature range. The relaxation time of the observed process exhibits a 1/q(2) dependence, proving that it is due to long-range translational diffusion. The Stokes-Einstein relation is used to estimate the hydrodynamic radius of the diffusing particles and from these calculations it is evident that the observed relaxation process is due to the Brownian motion of single or a few glycerol molecules. The fact that it is possible to study the self-diffusion of such small molecules may stimulate a broadening of the research field used to be covered by the DLS technique

A Dynamic CGE Model: An Application of R&D- Based Endogenous Growth Model Theory

An R&D based endogenous growth - applied general equilibrium model is developed from an underlying analytical model which combines Romer's capital variety with Grossman and Helpman's multi-sector open economy model. The transitional dynamics of the analytical model are derived. For numerical implementation, a time discrete empirical model, with an Armington structure, is fit to East Asian data of the social accounting matrix variety. Simulations of trade reform are performed and their static and dynamic effects compared. The transition paths of the state variables are found to have a half-life of five to six periods. A solution of the Social Planner's problem, and interventions which seek to obtain this outcome from the decentralized model are also obtained'.Applied General Equilibrium, Trade, Growth, International Relations/Trade, F11, 031, 041,

Environment in Three Classes of Endogenous Growth Models

The implications of environmental externalities are studied within three classes of endogenous growth models viz. the linear technology models, the human capital models, and the R&D and innovation models. The long-run rate of economic growth changes when environmental extemalities are introduced; the direction of change depends on the severity of extemalities and the intertemporal elasticity of substitution. The presence of environmental externalities cause the decentralized growth rate to diverge from the efficient rate. Which rate is bigger than the other depends, among other things, on the valuation of consumption relative to environmental quality. Several policy changes to align the two paths are discussed. The models are calibrated to U.S. data.Environmental Economics and Policy, International Development,

How preserved is emotion recognition in Alzheimer disease compared with behavioral variant frontotemporal dementia?

Background: Emotion deficits are a recognised biomarker for behavioural variant frontotemporal dementia (bvFTD), but recent studies have reported emotion deficits also in Alzheimer’s disease (AD). Methods: A hundred and twenty-three participants (33 AD, 60 bvFTD, 30 controls) were administered a facial emotion recognition test, to investigate the clinical factors influencing the diagnostic distinction on this measure. Binomial regression analysis revealed that facial emotion recognition in AD was influenced by disease duration and MMSE, whereas the same was not true for bvFTD. Based on this information, we median-split the AD group on disease duration (3 years) or MMSE (24) and compared the facial emotion recognition performance of mild-AD, moderate-AD, bvFTD patients and controls. Results: Results showed that very mild-AD performed consistently at control levels for all emotions. By contrast, mild/moderate-AD and bvFTD were impaired compared to controls on most emotions. Interestingly, mild/moderate-AD were significantly impaired compared to very mild-AD on total score, anger and sadness subscores. Logistic regression analyses corroborated these findings with ~94% of very mild-AD being successfully distinguished from bvFTD at presentation, while this distinction was reduced to ~78% for mild/moderate-AD. Conclusions: Facial emotion recognition in AD is influenced by disease progression, with very mild-AD being virtually intact for emotion performance. Mild/moderate-AD and bvFTD show consistent impairment in emotion recognition, with bvFTD being worse. A disease progression of over 3 years or a MMSE lower than 24 should warrant caution to put too much emphasis on emotion recognition performance in the diagnostic distinction of AD and bvFTD

Effects of aqueous extracts of basil, Ocimum basilicum L., Sodom's apple, Calotropis procera Ait and Coriander Coriandrum sativum L. on leaf miner, Liriomyza spp., on okra crop : PS7TH432 Others

The Hymenopterous parasitoids, Hemiptarsemus varicornis (Girault) and Opius dissitus (Muesebeck) are associated with the leaf miner, Liriomyza spp., populations in Central Sudan. The effects of Liriomyza trifolii (Burgess) and Liriomyza sativae (Blanchard) reared on common bean, Phaseolus vulgaris, on the development and efficiency of their two parasitoids were studied at constant conditions of temperature, relative humidity and photoperiod. No significant differences were found between parasitism percentage of H. varicornis or O. dissitus on L. trifolii or L. sativae. However, significant differences were found with respect to adult (male and female) life span as well as the number of adult parasitoids emerged of H. varicornis and O. dissitus. The life span of H. varicornis was shorter than that of O. dissitus, but more adults of the later emerged from the pupae than those of H. varicornis which might have accounted for their almost equal parasitism percentages. Also, no significant differences were recorded with regard to the development of H. varicornis on L. sativae reared on four of its host plants. However, parasitism percentage was significantly higher on gourd (Cucurbita moschata) followed by zucchini (cucurbita pepo), haricot bean (Phaseolus vulgaris) and tomato (Lycopersicon esulentium), respectively. (Résumé d'auteur