Laboratory evaluation of toxicity of Bacillus thuringiensis, neem oil and methamidophos against Plutella xylostella L. (Lepidoptera: Plutellidae) larvae

Diamondback moth (DBM), Plutella xylostella (L.), remains a major pest of brassica crops worldwide. Chemical control of this pest remains difficult due to the rapid development of resistance to insecticides and to their effect on natural enemies. The objective of this study was to assess the toxicity of Bacillus thuringiensis (Bt), neem oil and methamidophos on larvae of P. xylostella under laboratory conditions. Leaf-dip bioassay for DBM larvae was used to assess mortality. For each treatment, three doses (low, medium and high) were applied on cabbage leaves and presented to third instar larvae. Larval mortality was performed every 24 hours for a period of eight days. The application of the three dosages of Biobit was more effective against P. xylostella larvae when compared to the other treatments. However, there was no significant difference in larval mortality when all three doses of Biobit were tested compared to the control. Methamidophos was the least toxic treatments with high dosage recording the lowest mortality rate of 52.5%. These results showed that Btbased biopesticides and neem extracts could be of help, but their deployment should be part of an integrated pest management package, which recognizes the constraints of farmers while addressing the requirement to control of P. xylostella populations.Keywords: Diamondback moth, biopesticide, Azadirachta indica, cabbage, bioassay

Efficacite agronomique du compost a base de la biomasse du « neem » et de l’anacarde sur des cultures maraicheres dans la zone des Niayes au Senegal

Dans la zone des Niayes au Sénégal, les sols sont pauvres en matières organiques et en éléments nutritifs nécessaires aux plantes. Les engrais chimiques utilisés pour améliorer les rendements ont engendré une forte pollution des sols et de la  nappe phréatique. L’objectif de cette étude est d’évaluer la valeur agronomique du compost fabriqué à base des feuilles de neem et d’anacarde, de fiente de volaille et de la cendre de bois. Le compost obtenu présente un rapport C/N de 15,49 et des teneurs en N - P - K de 9,1, 14,8 et 7,3 mg/kg, respectivement. Les différentes doses du compost testées  sur  des  cultures  maraichères  ont  révélé  des  performances  agronomiques  meilleures par rapport aux témoins. La dose T3 (30 t/ha) a induit les meilleurs rendements pour la tomate (27,213 t/ha) et l’oignon (105,263 t/ha). Pour le chou et la pomme de terre, la dose T1 (10 t/ha) a permis d’obtenir les meilleurs rendements (144,533 t/ha et 55,163 t/ha, respectivement). Par contre pour le poivron, la dose T2 (20 t/ha) a favorisé les meilleurs rendements (32,534 t/ha) avec un poids moyen (81,748g) et un nombre de fruits/récolte considérablement plus élevé. Ce compost pourrait constituer une alternative réelle à l’utilisation abusive de l’engrais minéral dans la zone agricole des Niayes.Mots clés : Compost, Neem, Feuilles d’anacarde, Maraichage, Sénéga

Application of phytoremediation for heavy metal contaminated sites in the South Pacific: strategies, current challenges and future prospects

Effectively dealing with hazardous and recalcitrant pollutants such as heavy metals (HMs) has become a global challenge with limited options available for reprieve. This is true for Pacific Island Countries and Territories (PICTs) which have witnessed significant economic transitions and substantial increases hazardous waste depositions. Although several physico-chemical remediation techniques exist, the economic and geographic limitations of PICTs render them impractical for the region. Phytoremediation, a plant–based remediation technology which exploits hyperaccumulator plants to extract, accumulate and/or stabilize HMs, has received significant interest as a sustainable and non–intrusive remediation option. Nonetheless, improving the application and efficiency of phytoremediation programs not only requires a better understanding of the fundamental mechanisms governing HM accumulation and tolerance in plants, but also demands fast and reliable spectroscopic techniques for in–situ analysis. This review critically examines the current practices in phytoremediation and its prospects for the treatment of HM–contaminated sites in PICTs. We also review the limitations of traditional spectroscopic techniques such as inductively coupled plasma mass spectroscopy/atomic emission spectroscopy (ICP–MS/AES) and the promise of novel techniques such as field portable X–ray fluorescence spectrometry (FP–XRF), atmospheric pressure discharge plasma (APDP) and lab on chip (LOC) in phytoremediation studies

The dynamics and control of large flexible space structures-V

A general survey of the progress made in the areas of mathematical modelling of the system dynamics, structural analysis, development of control algorithms, and simulation of environmental disturbances is presented. The use of graph theory techniques is employed to examine the effects of inherent damping associated with LSST systems on the number and locations of the required control actuators. A mathematical model of the forces and moments induced on a flexible orbiting beam due to solar radiation pressure is developed and typical steady state open loop responses obtained for the case when rotations and vibrations are limited to occur within the orbit plane. A preliminary controls analysis based on a truncated (13 mode) finite element model of the 122m. Hoop/Column antenna indicates that a minimum of six appropriately placed actuators is required for controllability. An algorithm to evaluate the coefficients which describe coupling between the rigid rotational and flexible modes and also intramodal coupling was developed and numerical evaluation based on the finite element model of Hoop/Column system is currently in progress

Pathogenicity of local Metarhizium anisopliae var. acridum strains on Locusta migratoria migratorioides Reiche and Farmaire and Zonocerus variegatus Linnaeus in Senegal

Locusts and grasshoppers are the most important economical threat in the sahelian agricultural system. Principal control strategies of these pests are synthetic chemicals which are, however, harmful to the environment and human health. Metarhizium anisopliae based biopesticide Green Muscle IMI330189 has been recently developed for the control of locusts and grasshoppers. In this paper, we assessed the pathogenicity of three local strains of M. anisopliae var. acridum on Locusta migratoria migratorioides and Zonocerus variegatus, in comparison to the commercial product, IMI330189. There was various level of pathogenicity within the strains on the two pests. On L. migratoria, DPV5 caused the highest mortality after three weeks (91.2%). There was a significant difference between DPV5 and IMI330189. However, there were no significant differences between IMI330189 and the other strains. On Z. variegatus there were no significant differences between IMI330189 DPV5 and DPV10. DPV15 had the lowest pathogenic activity. Moreover, the comparison of susceptibility of both insect pests to Metarhizium strains showed that L. migratoria is more susceptible than Z. variegatus. DPV5 had the shortest LT50 on L. migratoria 7.1 days whereas on Z. variegatus, the LT50 value of DPV5 was comparable to IMI330189. Our study suggests that, DPV5 which was isolated from Kraussaria angulifera in Senegal is a promising candidate for future development for locusts and grasshoppers control in the country.Keywords: Green Muscle, African migratory locust, grasshoppers, local strains, biopesticide

Substances inertes et plantes à effet insecticide utilisées dans la lutte contre les insectes ravageurs des céréales et légumineuses au Sénégal et en Afrique de l’Ouest

La situation alimentaire est caractérisée au Sénégal et dans le Sahel par l’insuffisance des récoltes à laquelle s’ajoutent des pertes souvent élevées dues en grande partie aux attaques des insectes ravageurs au champ et dans les lieux de stockage. En Afrique subsaharienne, l’action des insectes déprédateurs de céréales et de légumineuses peut anéantir complètement, en quelques mois seulement, des stocks destinés aux vivres et aux semences si aucune protection n’est appliquée. Pour y apporter des solutions, les producteurs ont recours le plus souvent aux pesticides de synthèse. La résistance des insectes, les intoxications et les pollutions liées à l’utilisation des pesticides constituent de sérieux problèmes environnementaux et de santé publique. C’est ainsi que ces dernières années, de nombreux travaux ont été menés pour proposer des méthodes alternatives de protection, peu coûteuses et qui respectent l’environnement. Les insecticides naturels tels que les plantes à effet insecticide et les substances inertes (sable, cendre, terres à diatomées,…) méritent d’être valorisées afin de réduire l’utilisation des insecticides chimiques et protéger l’environnement. Ce travail basé sur une revue documentaire fouillée et actualisée vise à faire la genèse des méthodes alternatives de lutte contre les ravageurs des denrées en stockage en mettant l’accent sur les insecticides naturels et les substances inertes susceptibles d’améliorer la protection des récoltes sans danger. Les principales pratiques de stockage sont passées au peigne fin.Mots clés: Céréales, légumineuses, post-récolte, pesticides, substances inertes, plantes insecticides

Macroinvertebrate Communities Associated with Hydrilla verticillata (Royle, 1839) and Relationship with Environmental Factors in Ono Lagoon, Southeast of Côte d’Ivoire

The macroinvertebrates associated with Hydrilla verticillata was studied in Ono lagoon, South-eastern of Côte d'Ivoire. Monthly samples of macrophytes with their associated macroinvertebrates were collected in upstream, centre and downstreamusing a Van veen grab of 0.314 m2 internal area. The environmental variables (temperature, transparency, depth, conductivity, TDS, pH, dissolved oxygen, , , and ) were also recorded. A total of 71 taxa belonging to 28 families, 11 orders, 05 classes and 03 phyla of which 40 taxa were recorded in upstream, 45 taxa in centre and 44 taxa in downstream. Insects numerically dominated the capture, comprising 91.55% of the collectedtaxa with Odonata and Coleoptera being the most diverse and abundant groups. The density was higher in upstream (1407ind. per 100 g d.w.) and lower in downstream (1062 ind. per 100 g d.w.), whist theLibellulidae and Corduliidae exhibited the highest density communities. The rarefied richness did not show spatial variation but vary significantly between seasons. The Evenness did not show spatial and seasonal variations. However, Shannon diversity index varied significantly between sites and seasons. From the results of RDA analysis, conductivity and pH showed a strong environmental gradient and had a structuring effect on macroinvertebrate communities

Urban agriculture in Senegal: effect of wastewater on the agronomical performance and hygienic quality of tomato and lettuce

The use of wastewater in urban agriculture has gained a lot of interest in Senegal. The aim of this works was to assess the effect of wastewater on the agronomical performance of two vegetable crops and the hygienic threats as compared to tap water. We also compared the effect of irrigation mode and the addition of fertilizers. Results showed that there were no significant differences between the two irrigation modes. Thesturdiness at 2 months had a positive effect on the number of plant (tomato) at the harvest, the yield and fruit average weight. Considering the following parameters studied (overall yield, corrected yield, number of fruit per treatment and fruit average size, there were significant differences between plants (lettuce) treated with tap water and those treated with wastewater. In a chemical point of view, samples from aspersion and draining watering mode treatments were similar in term of their content in heavy metals. On the lettuce, results showed a low presence of worms on crop watered with wastewater. On the other hand, lettuce watered with theaspersion technique contents much more germs of pathogens than those watered in draining mode. As for tomato, there was a total absence of worms and other pathogenic germs in both irrigation modes. This studysuggests that use of wastewater in horticulture with a moderate fertilization and taking into account soil chemistry could be gainful to urban farmers. The study addresses the issue of preliminary studies on the wastewater and soil quality before deciding on the adequate crop to grow

A Decade of Partnering to Stop HIV in West Africa: GAIA VF Prevention, Education, Access to Care and Vaccine Trial Site Development in Bamako, Mali

Poster Presentation from AIDS Vaccine 2012 Boston, MA, USA. 9-12 September 201

Possible alternative for national supply of seed potatoes (Solanum tuberosum L.) from in vitro culture at the Agro-physio-genetic and Plants Biotechnology laboratory of IPR / IFRA of Katibougou, Mali

The enhancement of the potential for reducing food insecurity and poverty through potato cultivation in Mali is largely limited by difficult access to quality seed. In trying to find ways to reduce these shortcomings outlined above that work has been done. The objective of this work was to assess the economic profitability of the local potato seed sourcing scheme from in vitro propagation and to analyze the competitiveness of the sourcing scheme from imported elite seed. The technical and economic feasibility of the local potato seed supply scheme was assessed at five levels. The first concerns the production of vitro-plants in the laboratory, the second the production of mini zero generation tubers (G0). Regarding the other three levels of evaluation, they were carried out in collaboration with the seed cooperatives by successive multiplication from mini-tubers to obtain seeds of one “G1”, two “G2” and three “G3” generations". The profitability of the procurement scheme from the elite imported and multiplied once seed was evaluated in order to analyze its competitiveness in relation to the local circuit. The valuation indicates positive profit margins. However, it should be noted that the economic efficiency coefficients of vitro-propagation (0.77) and tunnel multiplication (0.75) are less than 1. The production cost of one kilogram of G3 is equal to at 463.39 F CFA. A profit margin of 456.61 F CFA / kg emerges between this unit production cost and the selling price of imported seeds, which amounts on average to 920 F CFA / kg. The production of plants is technically feasible and profitable with a cost price of one kg of G3 in the order of 500 to 600 F CFA against 900 to 1000 F CFA / kg for imported seed. La valorisation du potentiel de réduction de l’insécurité alimentaire et de la pauvreté à travers la culture de la pomme de terre au Mali est limitée en grande partie par l’accès difficile à la semence de qualité. En essayant de trouver des moyens pour réduire ces insuffisances soulignées ci-dessus que ce travail a été effectué. Le présent travail avait pour objectif d’évaluer la rentabilité économique du schéma d’approvisionnement locale en semences de pomme de terre à partir de la vitro propagation et d’analyser la compétitivité du schéma d’approvisionnement à partir de la semence élite importées. La faisabilité technico-économique du schéma d’approvisionnement local en semences de pomme de terre était évaluée à cinq niveaux. Le premier concerne la production de vitro-plants au laboratoire, le deuxième la production de mini tubercules de génération zéro (G0). Pour ce qui concerne les trois autres niveaux d’évaluation, ils ont été réalisés en collaboration avec les coopératives semencières par multiplications successives à partir de mini-tubercules pour obtenir des semences de génération une «G1», deux «G2» et trois «G3». La rentabilité, du schéma d’approvisionnement à partir de la semence élite importée et multipliée une fois, a été évaluée en vue d’analyser sa compétitivité en rapport avec le circuit local. L’évaluation indique des marges bénéficiaires positives. Cependant, il faut remarquer que les coefficients d’efficacité économiques de la vitro-propagation (0,77) et de la multiplication sous tunnels (0,75) sont inférieurs à 1. Le coût de production d’un kilogramme de G3 est égal à 463,39 F CFA. Une marge bénéficiaire de 456,61 F CFA / kg se dégage entre ce coût de production unitaire et le prix de vente des semences importées qui s’élève en moyenne à 920 F CFA / kg. La production de plants est techniquement faisable et rentable avec un coût de revient d’un kg de G3 de l’ordre de 500 à 600 F CFA contre 900 à 1 000 F CFA / kg pour la semence importée