Contributions of Aeromagnetic and Field Surveys to Geological and Structural Mapping of Pan-African Province of South Maradi, Southern Niger

This study focused on geological and structural mapping of Pan-African Province of South Maradi by using the aeromagnetic and filed surveys. The study zone corresponds to the northern part of the Benin-Nigerian Shield, belonging to the Pan-African mobile zone in the East of West African Craton. Previous geological work dates from the 1970s and limited to the summary geological map. According to this work, basement formations crop out discontinuously and are not subject by a structural study. In addition, the use of this map reveals a problem of correlation between the geological contours described on the existing map and those observed in the field. A combined analysis of aeromagnetic and field data led to complete then correct the petrographic and structural gap existing in the previous summary geological map since 1970s, which allowed to produce a new geological and structural map of studied zone (South Maradi Pan-African province). Petrographic and structural analysis of this new map shows that the spatial distribution of geological formations is characterized by the alternating Schist Belts and mylonitic gneiss Shear zones associated with migmatites panels and granitoïd intrusions. Thus, the different petrographic facies mapped are represented by schists-micaschist, mylonitic gneiss, migmatitic gneiss and intrusive porphyric granites. Previous data revealed a petrographic and structural continuity between South Maradi Pan-African formations with those of contiguous Pan-African province of North Nigeria

Carotenoids content and antibacterial activity from galls of Guiera senegalensis J.F. Gmel (combretaceae).

Guiera senegalensis is a well known medicinal plant which is used as a drug in Burkina Faso. The purpose of the present study was to investigate the carotenoids content and antibacterial activity from galls of Guiera senegalensis. The hydroacetonic extract (HAE) exhibited the highest of β-carotene (4.67±0.25 mg/g) and lycopene (0.99±0.0735 mg/g) content. The extracts and fractions of galls exhibited antimicrobial activity against some gram positive and gram negative bacteria. We observed an inhibitory activity of the extracts against Bacillus cereus ATCC 13061 and Staphylococus aureus ATCC 6538 which showed a resistance to the penicillin and ampicillin. The ratio of the MBC and the MIC showed that the hydroacetonic extract is bactericidal against all the bacterial strains used except for Proteus mirabilis ATCC 35659. The aqueous decoction extract is bactericidal against all the bacterial species tested. The present study thus suggested that galls from G senegalensis may be used as a new potential source of natural nutraceutical components

Population Size and Migration of Anopheles gambiae in the Bancoumana Region of Mali and Their Significance for Efficient Vector Control

We present results of two intensive mark-release-recapture surveys conducted during the wet and dry seasons of 2008 in the villages of Fourda and Kenieroba, Mali. The former is a small fishing village by the Niger River with a moderate to high densities of Anopheles gambiae Giles s.s. (Diptera: Culicidae) throughout the year, while the latter is a large agricultural community 2 km inland that experiences strong seasonal fluctuation in An. gambiae densities. We estimate the population size of female An. gambiae in Fourda to be in less than 3,000 during the dry season. We found evidence of large population size and migration from Fourda in Kenieroba during the wet season, but very low numbers and no sign of migrants during the dry season. We suggest that malaria vector control measures aimed at adult mosquitoes might be made more efficient in this region and other seasonal riparian habitats by targeting disruption of mosquito populations by the river during the dry season. This would decrease the size of an already small population, and would be likely to delay the explosive growth in vector numbers in the larger inland villages as rainfall increases

Dynamics of antigenemia and transmission intensity of Wuchereria bancrofti following cessation of mass drug administration in a formerly highly endemic region of Mali

Background After seven annual rounds of mass drug administration (MDA) in six Malian villages highly endemic for Wuchereria bancrofti (overall prevalence rate of 42.7%), treatment was discontinued in 2008. Surveillance was performed over the ensuing 5 years to detect recrudescence. Methods Circulating filarial antigen (CFA) was measured using immunochromatographic card tests (ICT) and Og4C3 ELISA in 6–7 year-olds. Antibody to the W. bancrofti infective larval stage (L3) antigen, Wb123, was tested in the same population in 2012. Microfilaraemia was assessed in ICT-positive subjects. Anopheles gambiae complex specimens were collected monthly using human landing catch (HLC) and pyrethrum spray catch (PSC). Anopheles gambiae complex infection with W. bancrofti was determined by dissection and reverse transcriptase polymerase chain reaction (RT-PCR) of mosquito pools. Results Annual CFA prevalence rates using ICT in children increased over time from 0% (0/289) in 2009 to 2.7% (8/301) in 2011, 3.9% (11/285) in 2012 and 4.5% (14/309) in 2013 (trend χ 2  = 11.85, df =3, P = 0.0006). Wb123 antibody positivity rates in 2013 were similar to the CFA prevalence by ELISA (5/285). Although two W. bancrofti-infected Anopheles were observed by dissection among 12,951 mosquitoes collected by HLC, none had L3 larvae when tested by L3-specific RT-PCR. No positive pools were detected among the mosquitoes collected by pyrethrum spray catch. Whereas ICT in 6–7 year-olds was the major surveillance tool, ICT positivity was also assessed in older children and adults (8–65 years old). CFA prevalence decreased in this group from 4.9% (39/800) to 3.5% (28/795) and 2.8% (50/1,812) in 2009, 2011 and 2012, respectively (trend χ 2  = 7.361, df =2, P = 0.0067). Some ICT-positive individuals were microfilaraemic in 2009 [2.6% (1/39)] and 2011 [8.3% (3/36)], but none were positive in 2012 or 2013. Conclusion Although ICT rates in children increased over the 5-year surveillance period, the decrease in ICT prevalence in the older group suggests a reduction in transmission intensity. This was consistent with the failure to detect infective mosquitoes or microfilaraemia. The threshold of ICT positivity in children may need to be re-assessed and other adjunct surveillance tools considered

Diversité interspécifique de l'efficience d'utilisation de l'eau des acacias sahéliens et australiens

The main objective of this work was to compare water use efficiency (WUE) among various Australian and Sahelian acacia species using isotope discrimination at leaf level ([delta]13Cf) and various methods of measurement. Acacia species exhibited a large inter-specific variability of [delta]13Cf. This variability was confirmed by direct leaf gas exchange measurements (intrinsic water use efficiency, Wi) and by measurement at the whole plant level (transpiration efficiency, TE). A large interspecific variability of leaf traits (stomatal density DS, leaf nitrogen concentration %N, specific leaf area SLA, net CO2 assimilation of the saturation Asat, stomatal conductance for water vapor of the saturation gssat) and growth characteristics (root shoot biomass ratio R/S) has also been reported. WUE was controlled for gssat. The hypothesis that the species from arid areas exhibit higher WUE was not confirmed. In contrast, the species from semi-wet area exhibited a higher WUE than those from semi-arid and arid zonesLe principal objectif de ce travail était de déterminer l'efficience d'utilisation de l'eau (WUE) de diverses espèces d'acacias d'origine Australienne et Sahélienne par la discrimination isotopique au niveau de la feuille ([delta]13Cf) et par différentes techniques de mesure. Les acacias ont montré une forte variabilité interspécifique de [delta]13Cf. Cette variabilité a été confirmée par les mesures directes d'échanges gazeux au niveau des feuilles (efficience intrinsèque d'utilisation de l'eau, Wi) et par des mesures effectuées au niveau de la plante entière (efficience de transpiration, TE). Une forte variabilité interspécifique des traits foliaires(densité stomatique DS, proportion d'azote dans les feuilles %N, surface massique SLA, assimilation nette du CO2 à la saturation Asat, conductance stomatique en vapeur d'eau à la saturation gssat) et de la croissance (ratio biomasse racinaire sur biomasse aérienne R/S) a également été constatée entre les espèces. WUE était pratiquement contrôlée par gssat.L'hypothèse selon laquelle les espèces se développant dans les zones arides présenteraient une WUE plus élevée n'a pas été vérifiée. Au contraire, les espèces des zones semi-humides ont présenté une WUE plus élevée que celles de zones semi-arides et arides

Identification of weeds in sweet potato crops (Ipomoea batatas) in the lowlands of Côte d'Ivoire

To ensure better management of weeds in sweet potato crops, in the lowlands of Anyama in Côte d'Ivoire, it is appropriate to first identify weeds, particularly the major species. To do this, 120 floristic surveys were carried out in four lowlands of pure sweet potato cultivation, i.e. 30 surveys in each lowland. This work has identified 110 species belonging to 79 genera distributed in 33 botanical families. The dominant families are represented by Cyperaceae (17.3%), Poaceae (16.4%), Asteraceae (10.0%), Fabaceae (5.4%) and Amaranthaceae (4.5%). Angiosperms are in the majority with 98.2% of the species recorded. Dicotyledons are the most represented with 60.0% of species against 38.2% for Monocotyledons. In terms of biological types, therophytes are the most represented with 39.0%, followed by nanophanerophytes, then hemicryptophytes with the same proportion (10.8%). The study area has a homogeneous floristic distribution. Digitaria horizontalis, Eleusine indica, Alternanthera sessilis and Ageratum conyzoides are the most damaging species to the crop in this area. Keywords: Anyama, lowland, sweet potato, weed, floristic surve

Diversité interspécifique de l'efficience d'utilisation de l'eau des acacias sahéliens et australiens

Le principal objectif de ce travail était de déterminer l efficience d utilisation de l eau (WUE) de diverses espèces d acacias d origine Australienne et Sahélienne par la discrimination isotopique au niveau de la feuille ( 13Cf) et par différentes techniques de mesure. Les acacias ont montré une forte variabilité interspécifique de 13Cf. Cette variabilité a été confirmée par les mesures directes d échanges gazeux au niveau des feuilles (efficience intrinsèque d utilisation de l eau, Wi) et par des mesures effectuées au niveau de la plante entière (efficience de transpiration, TE). Une forte variabilité interspécifique des traits foliaires(densité stomatique DS, proportion d azote dans les feuilles %N, surface massique SLA, assimilation nette du CO2 à la saturation Asat, conductance stomatique en vapeur d eau à la saturation gssat) et de la croissance (ratio biomasse racinaire sur biomasse aérienne R/S) a également été constatée entre les espèces. WUE était pratiquement contrôlée par gssat.L hypothèse selon laquelle les espèces se développant dans les zones arides présenteraient une WUE plus élevée n a pas été vérifiée. Au contraire, les espèces des zones semi-humides ont présenté une WUE plus élevée que celles de zones semi-arides et arides.The main objective of this work was to compare water use efficiency (WUE) among various Australian and Sahelian acacia species using isotope discrimination at leaf level ( 13Cf) and various methods of measurement. Acacia species exhibited a large inter-specific variability of 13Cf. This variability was confirmed by direct leaf gas exchange measurements (intrinsic water use efficiency, Wi) and by measurement at the whole plant level (transpiration efficiency, TE). A large interspecific variability of leaf traits (stomatal density DS, leaf nitrogen concentration %N, specific leaf area SLA, net CO2 assimilation of the saturation Asat, stomatal conductance for water vapor of the saturation gssat) and growth characteristics (root shoot biomass ratio R/S) has also been reported. WUE was controlled for gssat. The hypothesis that the species from arid areas exhibit higher WUE was not confirmed. In contrast, the species from semi-wet area exhibited a higher WUE than those from semi-arid and arid zonesNANCY1-Bib. numérique (543959902) / SudocSudocFranceF

LIPTAKOR : un outil d’accompagnement des orpailleurs du Liptako nigérien, pour les mettre en capacité de mieux connaître les enjeux environnementaux et sanitaires liés à leurs pratiques, et faire évoluer celles-ci

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LIPTAKOR : un outil d’accompagnement des orpailleurs du Liptako nigérien, pour les mettre en capacité de mieux connaître les enjeux environnementaux et sanitaires liés à leurs pratiques, et faire évoluer celles-ci

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Analyse Stratégique de la Gestion Environnementale: Regards croisés sur les interactions autour de l’exploitation minière artisanale dans le Liptako nigérien

International audienceLes formations birimiennes du Liptako nigérien, comme la majorité de ces formations du craton ouest africain (Ghana, Côte d’ivoire, Sénégal, Guinée, Burkina, Mali) sont riches en or. Cet or est exploité de manière artisanale ou industrielle avec des conséquences environnementales, sociales et sanitaires. Le cadre législatif en vigueur et les exigences de la gestion environnementale de l’exploitation artisanale d’or mis en œuvre par la majorité des pays africains concernés par cette exploitation, ne permettent pas de réduire significativement les impacts générés par cette activité. Au cours de ces dernières années, on constate un accroissement de l’exploitation artisanale de l’or sur le territoire nigérien dans le massif de l’Aïr et le Liptako nigérien avec l’ouverture de plusieurs sites d’exploitation artisanale. Cet accroissement des sites d’orpaillage a un lien direct avec la récente migration des réfugiés, causée par l’insécurité dans le Sahel. Le référentiel normatif majeur de l’analyse conduite est lié aux préoccupations socio-environnementales sur les contaminations par les éléments traces métalliques dont l’arsenic et des métaux lourds dans les puits et forages des zones d’orpaillage du Liptako nigérien. Les eaux extraites de ces puits sont destinées à la consommation humaine avec des risques d’exposition sanitaire des orpailleurs et des populations environnantes. Les différents acteurs intervenants sur la gestion environnementale de l’exploitation aurifère ont des visions diverses et variées sur la gestion effective et intentionnelle de l’activité sur ce territoire. Avec un objectif d’efficience à long terme pour le territoire, une analyse et une solution stratégiques d’intervention intégrant les interactions entre les différents acteurs ont été proposées en vue de limiter les impacts environnementaux et sanitaires des activités d’orpaillage sur la ressource en eau disponible pour la consommation humaine