Toxicite des extraits aqueux de azadirachta indica a. juss et de Jatropha curcas L. sur Plutella xylostella (L.) (lepidoptera : plutellidae) par contact

La teigne du chou Plutella xylostella (Linné) (Lepidoptera : Plutellidae) est le principal insecte nuisible des crucifères dans les régions  tropicales et subtropicales. Les larves de ce Lépidoptère sont défoliatrices et peuvent causer des pertes importantes de production malgré l’application des  pesticides. L’objectif de cette étude est d’évaluer l’effet toxique par contact des extraits aqueux de neem (Azadirachta indica) et de Jatropha (Jatropha curcas) sur les larves de Plutella xylostella au stade L2 au laboratoire. Cette toxicité des extraits aqueux de poudres de grains de neem (41,5 g/L ; 25,9 g/L ; 10,3 g/L) et de jatropha (59,1 g/L ; 36,9 g/L ; 14,7 g/L) et de pâtes de feuilles neem et de jatropha à différents concentrations a été évaluée par la détermination des CL50 en 24 heures et par la toxicité de chaque traitement au bout de 72 heures. Les résultats ont montré que les extraits aqueux de poudres de grains, de Azadirachta indica 41,5 g/L et de Jatropha curcas 59,1 g/L ont été plus toxiques que les insecticides Décis et Cypercal. Par ailleurs, les extraits aqueux, de pâtes de feuilles de jatropha 67 g/L et de feuilles de Azadirachta indica 67 g/L ont une toxicité similaire au Décis et au Cypercal. Ces extraits aqueux de Azadirachta indica et de Jatropha curcas peuvent donc substituer les pesticides Décis et Cypercal dans la lutte contre Plutella xylostella. Mots clés : Azadirhacta indica, Jatropha curcas, extraits aqueux, Plutella xylostella, toxicité   English Title: Contact toxicity of aqueous extracts of Azadirachta Indica A. Juss and Jatropha Curcas L. on Plutella Xylostella (L.) (Lepidoptera: Plutellidae) Cabbage moth Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) is a major pest of crucifers in the tropics and subtropics. Their larvae feed on cabbage and reduced cabbage yield despite the application of pesticides. The objective of this study was to determine the contact toxicity effect of aqueous extracts of Azadirachta indica and Jatropha curcas on the second instar larvae of P. xylostella. The toxicity of the various treatments of Azadirachta indica and Jatropha curcas seeds and leaves powders aqueous extracts were evaluated by determining the LC50 on 24 hours and by the toxicity effect of each treatment after 72 hours. The results showed that the seeds  powders aqueous extracts of Azadirachta indica 41.5 g/L and of Jatropha curcas 59.1 g / L were more toxic than the pesticides Decis and Cypercal on Plutella xylostella. Moreover, Jatropha curcas and Azadirachta indica leaves aqueous extracts 67 g / L have similar toxicity with Decis and Cypercal. The aqueous extracts of Azadirachta indica and Jatropha curcas can be used against Plutella xylostella. Keywords: Azadirhacta indica, Jatropha curcas, aqueous extracts, Plutella xylostella, toxicity

The effect of pesticides and aqueous extracts of Azadirachta indica (A. Juss) and Jatropha carcus L. on Bemisia tabaci (Gennadius) (Homoptera: Aleyrididae) and Helicoverpa armigera (Hübner)(Lepidoptera: Noctuidae) found on tomato plants in Côte d’Ivoire.

Objective: The objective was to evaluate the effects of foliar application of Jatropha and neem aqueous extracts compared to a conventional insecticide treatment on the number of whitefly Bemisia tabaci (Gennadius) and bollworm Helicoverpa armigera (Hübner), yield of tomatoes in plots and the potentials of using any of these aqueous extracts to control these insect pests.Methodology and results: the study was conducted in the region of Moronou (Bongouanou, Koffikro, CBC Kangandissou). The insecticides Décis 12 EC® and Cypercal 50 EC®, and neem and jatropha aqueous extract were used for tomato foliar treatment (neem and jatropha seeds 80 and 50g/L, neem leaves 67 g/L). The treatments of tomato plant plots with pesticides Decis® and Cypercal® showed similar yields of biopestcide made of neem and jatropha in Ahorosso (P=0.00), Bongouanou (P=0.07) and CBC Kangandissou (P=0.01) plots. All of these treatments reduced the number of Bemisia tabaci adults, reduced the number of Helicoverpa armigera larvae on tomato plants and increased number of fruits per plant, the fruit weight per plant and the yield.Conclusion and application of findings: Statistical analysis shows that aqueous extract of jatropha and neem seed 80 g/L and 50 g/L, and of neem leaves 67 g/L are as effective as pesticides Décis® and Cypercal® on Bemisia tabaci and Helicoverpa armigera. Consequently, these biopesticides increased the number of fruits per plant and yield. This result should enable use of aqueous extract of neem and jatropha seed and of neem leaves to protect tomato plants against Bemisia tabaci and  Helicoverpa armigera at farm.Keywords: Bemisia tabaci; Helicoverpa armigera; tomato crop; aqueous extract; biocontro

Etude de l'effet de l'amodiaquine sur les globules rouges infectés par le paludisme dans les images multispectrales

Nous avons montré que l’amodiaquine se fixe préférentiellement dans les globules rouges infectés et nous avons également été capable de retrouver les concentrations du médicament dans les cellules, à partir d’images multispectrales. Une scène d'images multispectrales de frottis sanguins non marqués est obtenue à partir d’une culture de plasmodium falciparum, à laquelle nous avons ajouté différentes doses d’amodiaquine (AQ) ; Les images sont obtenues à partir d'enregistrement de treize capteurs spectraux couplés à un microscope multimodal et multispectral. Ces images sont ensuite utilisées pour étudier l’interaction du médicament avec les globules rouges en fonction des concentrations, en ayant recours à des techniques d’analyse multivariée telles que la classification hiérarchique, la méthode des k-moyennes et l’analyse en composante principale. Les résultats obtenus nous montrent que l’imagerie multispectrale est un atout majeur pour le diagnostic médical et peut donc constituer une technique de routine pour l’étude de nouvelles molécules antipaludiques, notamment issues de la pharmacopée africaine.Mots-clés: imagerie multispectrale, classification hiérarchique, analyse en composante principale, k-moyennes.Study of the Effect of Amodiaquine on Red Blood Cells Infected by Malaria in Multispectral ImagesWe have demonstrated that amodiaquine binds preferentially in the infected red blood cells and we have also been able to retrieve the drug concentrations in the cells. A scene of multispectral images of free labelled blood smears have been obtained from plasmodium falciparum culture to which we have added different quantities of amodiaquine; the images have been recorded from thirteen spectral sensors coupled with a multimodal and multispectral microscope. These images have been used to study the interaction of the drug with the red blood cells as function of drug concentration by the use of multivariate statistical analysis techniques such as hierarchical classification, k-means method and principal component analysis techniques. The results show that the multispectral imagery is a key technique in medical technologies and can therefore be used as routine method for antimalarial drug design, especially in African traditional pharmacopeia study.Keywords: multispectral imagery; hierarchical classification; principal component analysis; k-means

Using conjoint analysis to estimate farmers' preferences for cattle traits in West Africa

This paper estimates the preferences of farmers for cattle traits in southern Burkina Faso using Conjoint analysis, a survey-based system for measuring preferences for multiple-attribute goods. Here the technique is used in the context of a West African country where literacy is low, where cattle perform multiple functions, where low-input management is the norm, and where cattle are exposed to a number of tropical diseases and other environmental stresses. The results reflect the production practices of the region, suggesting that important traits in developing breed improvement programs should include disease resistance, fitness for traction and reproductive performance. Beef and milk production are less important traits. The study shows the potential usefulness of conjoint analysis for quantifying preferences in less developed countries for livestock and for the wide variety of other multiple-attribute goods. Distinguishing differences in preferences between groups of respondents in connection with specific locations and production systems can be used to promote conservation-through-use of breeds at risk of extinction

Piégeage des Mouches des Fruits (Diptera : Tephritidae) À Base D’extraits de Ocimum Basilicum L. (Lamiaceae) : Cas de Bactrocera Dorsalis, Principal Ravageur de Mangues en Côte d’Ivoire

Les cultures fruitières, en particulier la mangue en Côte d’Ivoire, sont sous la menace des mouches des fruits. Les dégâts se sont accrus avec l’invasion de Bactrocera dorsalis. En outre, la baisse des pertes en vergers de manguiers exige l’utilisation du méthyl eugénol pour sa détection et le suivi du monitoring de sa population. Malheureusement, les attractifs sexuels spécifiques de mouchessont inaccessibles aux producteurs de la Côte d’Ivoire. L’objectif de cette étude est d’évaluer l’efficacité de Ocimum basilicum dans de la capture de B. dorsalis. Ces trois formulations du basilic (feuilles fraîches malaxées, poudre de basilic et macérât du basilic) et le méthyl eugénol sont utilisées en piégeage dans les vergers de manguiers à Korhogo. Les pièges ont été relevés chaque semaine et chaque jour respectivement pour le Méthyl eugénol et les formulations du basilic. Les formulations ont permis de capturer une importante population de B. dorsalis (99,41 %) avec une prévalence (FTD) moyenne journalière de 10,141 individus/jour/piège et d’autres espèces de mouches de fruits. La poudre de basilic montre une rémanence plus longue (28,67 ± 18,17 jours) tandis que le macérât de basilic montre une capture hebdomadaire plus élevée (513,4 ± 72,34 individus). Les captures moyennes les plus élevées ont été observées avec le Macérât de basilic (4419 ± 1090 individus) et le Méthyl eugénol (4899,67 ± 1511,74 individus). Le macérât de feuilles fraîches de basilic et la poudre de feuilles sèches de basilic peuvent être recommandées auprès des producteurs de mangues dans la lutte contre B. dorsalis. Fruit crops, especially mangoes in Côte d'Ivoire are threatened by the fruit flies. The damage has increased with the invasion of Bactrocera dorsalis. In addition, the decline in mango orchard losses requires the use of methyl eugenol for the detection and monitoring of Bactrocera population. Unfortunately, the sex-specific attractants of flies are inaccessible to producers in Côte d'Ivoire. The aims of this study is to evaluate the efficacy of Ocimum basilicum in the capture of B. dorsalis. Three basil formulations (fresh mixed leaves, basil powder and basil macerate) and methyl eugenol are used for trapping in mango orchards in Korhogo. The captured insects were collected weekly and daily for methyl eugenol and basil formulations respectively. The formulations captured a large population of B. dorsalis (99.41%) with an average daily prevalence (FTD) of 10,141 individuals / day / trap and other fruit fly species. Basil powder has the longest persistence (28.67 ± 18.17 days) and basil macerate has the highest weekly catch (513.4 ± 72.34 individuals). The highest average catches were observed with basil macerate (4419 ± 1090 individuals) and methyl eugenol (4899.67 ± 1511.74 individuals). Fresh basil leaf macerate and dry basil leaf powder may be recommended to mango growers in the control of B. dorsalis

Impact de la Cochenille Phenacoccus manihoti (Homoptera, Pseudococcidae) sur les rendements du manioc (Manihot esculenta) au Gabon

La cochenille Phenacoccus manihoti est l’une des causes de la chute des rendements du manioc au Gabon. Par la randomisation, nous avons étudié  son impact sur la croissance de la plante et sur les rendements du manioc. P. manihoti réduit la croissance des plants à 40%, la distance entrenoeuds  des tiges à 45%. Il diminue le nombre, la longueur et le diamètre des tubercules ; respectivement pour le nombre de 7 à 4, de 34 à 9  cm pour la longueur et de 10 à 5 cm pour le diamètre en moyenne. L’action de la cochenille P. manihoti induit ainsi la dimunition de la croissance des  plants et la baisse des rendements du manioc au Gabon. Pour protéger le manioc contre la cochenille, nous pensons que l’utilisation des  techniques de lutte efficaces est indispensable. Elles pourraient même être associées, dans le cadre d’une lutte intégrée, excluant complètement la  lutte chimique, à l’origine de beaucoup de problèmes environnementaux. Les auteurs ont enfin attiré l’attention des gouvernements africains sur la  nécessité de promouvoir les politiques de développement agricole dans leurs pays. English title: Impact of the mealybug Phenacoccus manihoti (homoptera, pseudococcidae) on the yields of the cassava (Manihot esculenta) in Gabon The mealybug Phenacoccus manihoti is one of the causes in the drop of cassava yields in Gabon. Through the randomization, we have studied its  impact on the growth of the plant and on the yields of the cassava. P. manihoti reduces the growth of the plants to 40%, the interval among knots of  the stems to 45%. Its diminishes the number, the length and the diameter of the tubercules, respectively for the number of 7 to 4; of 34 to 9cm for  the length and for 10 to 5cm for the average diameter. Thus, the share of the mealybug P. manihoti induces the lessening of the growth of the plants  and the drop of the cassava yields in Gabon. For protect the cassava against the mealybug we think that the using of the efficient fight  techniques is indispensable. They must even be assoociated in integrated fight excuding completely the chemical fight which induces meny  environemental problems. At last the authors have attracted the car of the african governments abut the necessity to upgrade the agricultural  development politics in theirs contries.&nbsp

Different environmental variables predict distribution and cover of the introduced red seaweed Eucheuma denticulatum in two geographical locations

In this study we examined abiotic and biotic factors that could potentially influence the presence of a non-indigenous seaweed, Eucheuma denticulatum, in two locations, one outside (Kane'ohe Bay, Hawai'i, USA) and one within (Mafia Island, Tanzania) its natural geographical range. We hypothesized that the availability of hard substrate and the amount of wave exposure would explain distribution patterns, and that higher abundance of herbivorous fishes in Tanzania would exert stronger top-down control than in Hawai'i. To address these hypotheses, we surveyed E. denticulatum in sites subjected to different environmental conditions and used generalized linear mixed models (GLMM) to identify predictors of E. denticulatum presence. We also estimated grazing intensity on E. denticulatum by surveying the type and the amount of grazing scars. Finally, we used molecular tools to distinguish between indigenous and non-indigenous strains of E. denticulatum on Mafia Island. In Kane'ohe Bay, the likelihood of finding E. denticulatum increased with wave exposure, whereas on Mafia Island, the likelihood increased with cover of coral rubble, and decreased with distance from areas of introduction (AOI), but this decrease was less pronounced in the presence of coral rubble. Grazing intensity was higher in Kane'ohe Bay than on Mafia Island. However, we still suggest that efforts to reduce non-indigenous E. denticulatum should include protection of important herbivores in both sites because of the high levels of grazing close to AOI. Moreover, we recommend that areas with hard substrate and high structural complexity should be avoided when farming non-indigenous strains of E. denticulatum

Direct penetration of spin-triplet superconductivity into a ferromagnet in Au/SrRuO3/Sr2RuO4 junctions

Efforts have been ongoing to establish superconducting spintronics utilizing ferromagnet/superconductor heterostructures1. Previously reported devices are based on spin-singlet superconductors (SSCs), where the spin degree of freedom is lost. Spin-polarized supercurrent induction in ferromagnetic metals (FMs) is achieved even with SSCs, but only with the aid of interfacial complex magnetic structures, which severely affect information imprinted to the electron spin. Use of spin-triplet superconductors (TSCs) with active spins potentially overcomes this difficulty and further leads to novel functionalities. Here, we report spin-triplet superconductivity induction into a FM SrRuO3 from a leading TSC candidate Sr2RuO4, by fabricating microscopic devices using an epitaxial SrRuO3/Sr2RuO4 hybrid. The differential conductance, exhibiting Andreev-reflection features with multiple energy scales up to around half tesla, indicates the penetration of superconductivity over a considerable distance of 15 nm across the SrRuO3 layer without help of interfacial complex magnetism. This demonstrates the first FM/TSC device exhibiting the spin-triplet proximity effect