Crop pests are a major constraint to the intensification of agricultural production in the tropic... more Crop pests are a major constraint to the intensification of agricultural production in the tropics, with novel issues related to global change (climate, land use, biological invasions, etc.), food security and preservation of natural resources and biodiversity. A research, extension and education network called DIVECOSYS (Diversity of cropping systems and ecologically-based pest management in West Africa) was launched in 2010 to synergize applied research actions in response to growing concerns on the vulnerability of agricultural systems to pest management in West Africa. This scientific network brings together research and academic institutions, with expertise spanning a multidisciplinary perspective from biology and ecology to remote sensing, agronomy and integrated pest management. Its main scientific objective is to explore the potential of biodiversity and ecological processes such as pest regulation, enabling novel ecologically-based models for productive systems, reduction of pesticide use, and adaptation or resilience of farming systems in the face of environmental disruptions. From Northern Senegal to Southern Benin, the research group explores a wide range of ecoregions and socio-ecological contexts, including stakeholders and their objectives, land use and agricultural practices, and management of biodiversity for enhancing biological control. Main challenges to be turned into opportunities include (i) encouraging collaborations amongst researchers from different scientific fields, (ii) fostering interactive research and synergies among research institutions and among countries, and (iii) developing an ecological engineering approach for the design of sustainable agricultural systems for smallholder farmers.
Landscape ecology is a discipline that has shown an increasing interest to understand certain pes... more Landscape ecology is a discipline that has shown an increasing interest to understand certain pest problems and their control by natural enemies in temperate climate. In Benin, in a very different climatic, social and economic context compared to Europe, this approach was carried out in two lowland rice cropping systems during the rainy season, with a specific focus on stem and cob borers. The landscape was mapped and studied regarding its composition and structure and pest species were identified. A high variability of infestation was observed in a context of relatively low pest pressure. This paper presents the preliminary results which still need to be analyzed thoroughly.
Hydrology and Earth System Sciences Discussions, 2010
A hydrologic pond model was developed that simulates daily spatial and temporal variations (area,... more A hydrologic pond model was developed that simulates daily spatial and temporal variations (area, volume and height) of temporary ponds around Barkedji, a village located in the Ferlo Region in Senegal. The model was tested with rainfall input data from a meteorological station and from Tropical Rainfall Measuring Mission (TRMM) satel-5 lites. During calibration phase, we used climatic, hydrologic and topographic field data of Barkedji pond collected daily during the 2002 rainy season. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Digital Elevation Model (DEM) and a QuickBird satellite image acquired in August 2005 (2.5 m pixel size) were used to apply the hydrologic model to all ponds (98 ponds) of the study area. With input 10 rainfall data from the meteorological station, simulated water heights values for years 2001 and 2002 were significantly correlated with observed water heights for Furdu, Mous 2 and Mous 3 ponds, respectively with 0.81, 0.67 and 0.88 Nash coefficients. With rainfall data from TRMM satellite as model input, correlations were lower, particularly for year 2001. For year 2002, the results were acceptable with 0.61, 0.65 and 15
We report results of the ab initio calculations on the electronic and magnetic properties of GdM2... more We report results of the ab initio calculations on the electronic and magnetic properties of GdM2 (M=Fe, Co, and Ni) intermetallic compounds. The magnetic structure in various GdM2 intermetallics is intimately related to the interplay of the exchange and the crystal field. Owing to the pure s-state of Gd the influence of the crystal field in the GdM2 compounds is
Background: West Nile virus (WNV) is a widespread pathogen maintained in an enzootic cycle betwee... more Background: West Nile virus (WNV) is a widespread pathogen maintained in an enzootic cycle between mosquitoes and birds with occasional spill-over into dead-end hosts such as horses and humans. Migratory birds are believed to play an important role in its dissemination from and to the Palaearctic area, as well as its local dispersion between wintering sites. The Djoudj Park, located in Senegal, is a major wintering site for birds migrating from Europe during the study period (Sept. 2008-Jan. 2009). In this work, we studied the seasonal feeding behaviour dynamics of the potential WNV mosquito vectors at the border of the Djoudj Park, using a reference trapping method (CDC light CO 2 -baited traps) and two host-specific methods (horse-and pigeon-baited traps). Blood meals of engorged females were analysed to determine their origin.
International Journal of Applied Earth Observation and Geoinformation, 2009
Remote sensing methods for locating and monitoring temporary ponds over large areas in arid lands... more Remote sensing methods for locating and monitoring temporary ponds over large areas in arid lands were tested on a study site in Northern Senegal. Three main results are presented, validated with field data and intended to highlight different spectral, spatial and temporal characteristics of the methods: 1) Among several water indices tested, two Middle Infra-Red-based indices (MNDWI -Modified Difference Water Index and NDWI 2 -Normalized Difference Water Index) are found to be most efficient; 2) an objective method is given prescribing the necessary sensor spatial resolution in terms of minimal detected pond area;
Helicoverpa armigera (H€ ubner) (Lepidoptera: Noctuidae) is a polyphagous pest of global importan... more Helicoverpa armigera (H€ ubner) (Lepidoptera: Noctuidae) is a polyphagous pest of global importance, threatening several key crops, including cotton. This study analysed the influence of landscape composition and agricultural practices on (i) the abundance of H. armigera larvae, and (ii) the proportion of infested plants (infestation) in cotton fields in northern Benin. In 2011 and 2012, the abundance of H. armigera was monitored during the rainy period, with weekly observations of 50 cotton plants in 20 fields selected each year. We selected cotton fields based upon the composition of the surrounding landscape (cotton, tomato and maize fields, and areas of natural vegetation) within 500 metres radius buffers. We also recorded agricultural practices, included sowing date, crop rotation, and frequencies of weeding and of treatment with insecticides. In testing for a relationship between the pest problem and landscape and management, we fitted logistic multiple regression models and compared all the possible models using an information-theoretic approach. Cotton fields surrounded by cotton crops were found to have significantly higher infestation rates. Natural vegetation was positively correlated with the level of infestation. This study highlights the importance of considering both landscape variables and agricultural practices to improve strategies management of H. armigera.
Background: Rift Valley fever (RVF) is a vector-borne viral zoonosis of increasing global importa... more Background: Rift Valley fever (RVF) is a vector-borne viral zoonosis of increasing global importance. RVF virus (RVFV) is transmitted either through exposure to infected animals or through bites from different species of infected mosquitoes, mainly of Aedes and Culex genera. These mosquitoes are very sensitive to environmental conditions, which may determine their presence, biology, and abundance. In East Africa, RVF outbreaks are known to be closely associated with heavy rainfall events, unlike in the semi-arid regions of West Africa where the drivers of RVF emergence remain poorly understood. The assumed importance of temporary ponds and rainfall temporal distribution therefore needs to be investigated.
Introduction: Dynamics of most of vector-borne diseases are strongly linked to global and local e... more Introduction: Dynamics of most of vector-borne diseases are strongly linked to global and local environmental changes. Landscape changes are indicators of human activities or natural processes that are likely to modify the ecology of the diseases. Here, a landscape approach developed at a local scale is proposed for extracting mosquito favourable biotopes, and for testing ecological parameters when identifying risk areas of Rift Valley fever (RVF) transmission. The study was carried out around Barkedji village, Ferlo region, Senegal.
Background: Landscape attributes influence spatial variations in disease risk or incidence. We pr... more Background: Landscape attributes influence spatial variations in disease risk or incidence. We present a review of the key findings from eight case studies that we conducted in Europe and West Africa on the impact of land changes on emerging or re-emerging vector-borne diseases and/or zoonoses. The case studies concern West Nile virus transmission in Senegal, tick-borne encephalitis incidence in Latvia, sandfly abundance in the French Pyrenees, Rift Valley Fever in the Ferlo (Senegal), West Nile Fever and the risk of malaria re-emergence in the Camargue, and rodent-borne Puumala hantavirus and Lyme borreliosis in Belgium.
In the Ferlo Region in Senegal, livestock depend on temporary ponds for water but are exposed to ... more In the Ferlo Region in Senegal, livestock depend on temporary ponds for water but are exposed to the Rift Valley Fever (RVF), a disease transmitted to herds by mosquitoes which develop in these ponds. Mosquito abundance is related to the emptying and filling phases of the ponds, and in order to study the epidemiology of RVF, pond modelling is required. In the context of a data scarce region, a simple hydrologic model which makes use of remote sensing data was developed to simulate pond water dynamics from daily rainfall. Two sets of ponds were considered: those located in the main stream of the Ferlo Valley whose hydrological dynamics are essentially due to runoff, and the ponds located outside, which are smaller and whose filling mechanisms are mainly due to direct rainfall. Separate calibrations and validations were made for each set of ponds. Calibration was performed from daily field data (rainfall, water level) collected during the 2001 and 2002 rainy seasons and from three different sources of remote sensing data: 1) very high spatial resolution optical satellite images to access pond location and surface area at given dates, 2) Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Digital Elevation Model (DEM) data to estimate pond catchment Correspondence to: V. Soti ([email protected]) area and 3) Tropical Rainfall Measuring Mission (TRMM) data for rainfall estimates. The model was applied to all ponds of the study area, the results were validated and a sensitivity analysis was performed. Water height simulations using gauge rainfall as input were compared to water level measurements from four ponds and Nash coefficients >0.7 were obtained. Comparison with simulations using TRMM rainfall data gave mixed results, with poor water height simulations for the year 2001 and good estimations for the year 2002. A pond map derived from a Quickbird satellite image was used to assess model accuracy for simulating pond water areas for all the ponds of the study area. The validation showed that modelled water areas were mostly underestimated but significantly correlated, particularly for the larger ponds. The results of the sensitivity analysis showed that parameters relative to pond shape and catchment area estimation have less effects on model simulation than parameters relative to soil properties (rainfall threshold causing runoff in dry soils and the coefficient expressing soil moisture decrease with time) or the water loss coefficient. Overall, our results demonstrate the possibility of using a simple hydrologic model with remote sensing data to track pond water heights and water areas in a homogeneous arid area.
Crop pests are a major constraint to the intensification of agricultural production in the tropic... more Crop pests are a major constraint to the intensification of agricultural production in the tropics, with novel issues related to global change (climate, land use, biological invasions, etc.), food security and preservation of natural resources and biodiversity. A research, extension and education network called DIVECOSYS (Diversity of cropping systems and ecologically-based pest management in West Africa) was launched in 2010 to synergize applied research actions in response to growing concerns on the vulnerability of agricultural systems to pest management in West Africa. This scientific network brings together research and academic institutions, with expertise spanning a multidisciplinary perspective from biology and ecology to remote sensing, agronomy and integrated pest management. Its main scientific objective is to explore the potential of biodiversity and ecological processes such as pest regulation, enabling novel ecologically-based models for productive systems, reduction of pesticide use, and adaptation or resilience of farming systems in the face of environmental disruptions. From Northern Senegal to Southern Benin, the research group explores a wide range of ecoregions and socio-ecological contexts, including stakeholders and their objectives, land use and agricultural practices, and management of biodiversity for enhancing biological control. Main challenges to be turned into opportunities include (i) encouraging collaborations amongst researchers from different scientific fields, (ii) fostering interactive research and synergies among research institutions and among countries, and (iii) developing an ecological engineering approach for the design of sustainable agricultural systems for smallholder farmers.
Crop pests are a major constraint to the intensification of agricultural production in the tropic... more Crop pests are a major constraint to the intensification of agricultural production in the tropics, with novel issues related to global change (climate, land use, biological invasions, etc.), food security and preservation of natural resources and biodiversity. A research, extension and education network called DIVECOSYS (Diversity of cropping systems and ecologically-based pest management in West Africa) was launched in 2010 to synergize applied research actions in response to growing concerns on the vulnerability of agricultural systems to pest management in West Africa. This scientific network brings together research and academic institutions, with expertise spanning a multidisciplinary perspective from biology and ecology to remote sensing, agronomy and integrated pest management. Its main scientific objective is to explore the potential of biodiversity and ecological processes such as pest regulation, enabling novel ecologically-based models for productive systems, reduction of pesticide use, and adaptation or resilience of farming systems in the face of environmental disruptions. From Northern Senegal to Southern Benin, the research group explores a wide range of ecoregions and socio-ecological contexts, including stakeholders and their objectives, land use and agricultural practices, and management of biodiversity for enhancing biological control. Main challenges to be turned into opportunities include (i) encouraging collaborations amongst researchers from different scientific fields, (ii) fostering interactive research and synergies among research institutions and among countries, and (iii) developing an ecological engineering approach for the design of sustainable agricultural systems for smallholder farmers.
Landscape ecology is a discipline that has shown an increasing interest to understand certain pes... more Landscape ecology is a discipline that has shown an increasing interest to understand certain pest problems and their control by natural enemies in temperate climate. In Benin, in a very different climatic, social and economic context compared to Europe, this approach was carried out in two lowland rice cropping systems during the rainy season, with a specific focus on stem and cob borers. The landscape was mapped and studied regarding its composition and structure and pest species were identified. A high variability of infestation was observed in a context of relatively low pest pressure. This paper presents the preliminary results which still need to be analyzed thoroughly.
Hydrology and Earth System Sciences Discussions, 2010
A hydrologic pond model was developed that simulates daily spatial and temporal variations (area,... more A hydrologic pond model was developed that simulates daily spatial and temporal variations (area, volume and height) of temporary ponds around Barkedji, a village located in the Ferlo Region in Senegal. The model was tested with rainfall input data from a meteorological station and from Tropical Rainfall Measuring Mission (TRMM) satel-5 lites. During calibration phase, we used climatic, hydrologic and topographic field data of Barkedji pond collected daily during the 2002 rainy season. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Digital Elevation Model (DEM) and a QuickBird satellite image acquired in August 2005 (2.5 m pixel size) were used to apply the hydrologic model to all ponds (98 ponds) of the study area. With input 10 rainfall data from the meteorological station, simulated water heights values for years 2001 and 2002 were significantly correlated with observed water heights for Furdu, Mous 2 and Mous 3 ponds, respectively with 0.81, 0.67 and 0.88 Nash coefficients. With rainfall data from TRMM satellite as model input, correlations were lower, particularly for year 2001. For year 2002, the results were acceptable with 0.61, 0.65 and 15
We report results of the ab initio calculations on the electronic and magnetic properties of GdM2... more We report results of the ab initio calculations on the electronic and magnetic properties of GdM2 (M=Fe, Co, and Ni) intermetallic compounds. The magnetic structure in various GdM2 intermetallics is intimately related to the interplay of the exchange and the crystal field. Owing to the pure s-state of Gd the influence of the crystal field in the GdM2 compounds is
Background: West Nile virus (WNV) is a widespread pathogen maintained in an enzootic cycle betwee... more Background: West Nile virus (WNV) is a widespread pathogen maintained in an enzootic cycle between mosquitoes and birds with occasional spill-over into dead-end hosts such as horses and humans. Migratory birds are believed to play an important role in its dissemination from and to the Palaearctic area, as well as its local dispersion between wintering sites. The Djoudj Park, located in Senegal, is a major wintering site for birds migrating from Europe during the study period (Sept. 2008-Jan. 2009). In this work, we studied the seasonal feeding behaviour dynamics of the potential WNV mosquito vectors at the border of the Djoudj Park, using a reference trapping method (CDC light CO 2 -baited traps) and two host-specific methods (horse-and pigeon-baited traps). Blood meals of engorged females were analysed to determine their origin.
International Journal of Applied Earth Observation and Geoinformation, 2009
Remote sensing methods for locating and monitoring temporary ponds over large areas in arid lands... more Remote sensing methods for locating and monitoring temporary ponds over large areas in arid lands were tested on a study site in Northern Senegal. Three main results are presented, validated with field data and intended to highlight different spectral, spatial and temporal characteristics of the methods: 1) Among several water indices tested, two Middle Infra-Red-based indices (MNDWI -Modified Difference Water Index and NDWI 2 -Normalized Difference Water Index) are found to be most efficient; 2) an objective method is given prescribing the necessary sensor spatial resolution in terms of minimal detected pond area;
Helicoverpa armigera (H€ ubner) (Lepidoptera: Noctuidae) is a polyphagous pest of global importan... more Helicoverpa armigera (H€ ubner) (Lepidoptera: Noctuidae) is a polyphagous pest of global importance, threatening several key crops, including cotton. This study analysed the influence of landscape composition and agricultural practices on (i) the abundance of H. armigera larvae, and (ii) the proportion of infested plants (infestation) in cotton fields in northern Benin. In 2011 and 2012, the abundance of H. armigera was monitored during the rainy period, with weekly observations of 50 cotton plants in 20 fields selected each year. We selected cotton fields based upon the composition of the surrounding landscape (cotton, tomato and maize fields, and areas of natural vegetation) within 500 metres radius buffers. We also recorded agricultural practices, included sowing date, crop rotation, and frequencies of weeding and of treatment with insecticides. In testing for a relationship between the pest problem and landscape and management, we fitted logistic multiple regression models and compared all the possible models using an information-theoretic approach. Cotton fields surrounded by cotton crops were found to have significantly higher infestation rates. Natural vegetation was positively correlated with the level of infestation. This study highlights the importance of considering both landscape variables and agricultural practices to improve strategies management of H. armigera.
Background: Rift Valley fever (RVF) is a vector-borne viral zoonosis of increasing global importa... more Background: Rift Valley fever (RVF) is a vector-borne viral zoonosis of increasing global importance. RVF virus (RVFV) is transmitted either through exposure to infected animals or through bites from different species of infected mosquitoes, mainly of Aedes and Culex genera. These mosquitoes are very sensitive to environmental conditions, which may determine their presence, biology, and abundance. In East Africa, RVF outbreaks are known to be closely associated with heavy rainfall events, unlike in the semi-arid regions of West Africa where the drivers of RVF emergence remain poorly understood. The assumed importance of temporary ponds and rainfall temporal distribution therefore needs to be investigated.
Introduction: Dynamics of most of vector-borne diseases are strongly linked to global and local e... more Introduction: Dynamics of most of vector-borne diseases are strongly linked to global and local environmental changes. Landscape changes are indicators of human activities or natural processes that are likely to modify the ecology of the diseases. Here, a landscape approach developed at a local scale is proposed for extracting mosquito favourable biotopes, and for testing ecological parameters when identifying risk areas of Rift Valley fever (RVF) transmission. The study was carried out around Barkedji village, Ferlo region, Senegal.
Background: Landscape attributes influence spatial variations in disease risk or incidence. We pr... more Background: Landscape attributes influence spatial variations in disease risk or incidence. We present a review of the key findings from eight case studies that we conducted in Europe and West Africa on the impact of land changes on emerging or re-emerging vector-borne diseases and/or zoonoses. The case studies concern West Nile virus transmission in Senegal, tick-borne encephalitis incidence in Latvia, sandfly abundance in the French Pyrenees, Rift Valley Fever in the Ferlo (Senegal), West Nile Fever and the risk of malaria re-emergence in the Camargue, and rodent-borne Puumala hantavirus and Lyme borreliosis in Belgium.
In the Ferlo Region in Senegal, livestock depend on temporary ponds for water but are exposed to ... more In the Ferlo Region in Senegal, livestock depend on temporary ponds for water but are exposed to the Rift Valley Fever (RVF), a disease transmitted to herds by mosquitoes which develop in these ponds. Mosquito abundance is related to the emptying and filling phases of the ponds, and in order to study the epidemiology of RVF, pond modelling is required. In the context of a data scarce region, a simple hydrologic model which makes use of remote sensing data was developed to simulate pond water dynamics from daily rainfall. Two sets of ponds were considered: those located in the main stream of the Ferlo Valley whose hydrological dynamics are essentially due to runoff, and the ponds located outside, which are smaller and whose filling mechanisms are mainly due to direct rainfall. Separate calibrations and validations were made for each set of ponds. Calibration was performed from daily field data (rainfall, water level) collected during the 2001 and 2002 rainy seasons and from three different sources of remote sensing data: 1) very high spatial resolution optical satellite images to access pond location and surface area at given dates, 2) Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Digital Elevation Model (DEM) data to estimate pond catchment Correspondence to: V. Soti ([email protected]) area and 3) Tropical Rainfall Measuring Mission (TRMM) data for rainfall estimates. The model was applied to all ponds of the study area, the results were validated and a sensitivity analysis was performed. Water height simulations using gauge rainfall as input were compared to water level measurements from four ponds and Nash coefficients >0.7 were obtained. Comparison with simulations using TRMM rainfall data gave mixed results, with poor water height simulations for the year 2001 and good estimations for the year 2002. A pond map derived from a Quickbird satellite image was used to assess model accuracy for simulating pond water areas for all the ponds of the study area. The validation showed that modelled water areas were mostly underestimated but significantly correlated, particularly for the larger ponds. The results of the sensitivity analysis showed that parameters relative to pond shape and catchment area estimation have less effects on model simulation than parameters relative to soil properties (rainfall threshold causing runoff in dry soils and the coefficient expressing soil moisture decrease with time) or the water loss coefficient. Overall, our results demonstrate the possibility of using a simple hydrologic model with remote sensing data to track pond water heights and water areas in a homogeneous arid area.
Crop pests are a major constraint to the intensification of agricultural production in the tropic... more Crop pests are a major constraint to the intensification of agricultural production in the tropics, with novel issues related to global change (climate, land use, biological invasions, etc.), food security and preservation of natural resources and biodiversity. A research, extension and education network called DIVECOSYS (Diversity of cropping systems and ecologically-based pest management in West Africa) was launched in 2010 to synergize applied research actions in response to growing concerns on the vulnerability of agricultural systems to pest management in West Africa. This scientific network brings together research and academic institutions, with expertise spanning a multidisciplinary perspective from biology and ecology to remote sensing, agronomy and integrated pest management. Its main scientific objective is to explore the potential of biodiversity and ecological processes such as pest regulation, enabling novel ecologically-based models for productive systems, reduction of pesticide use, and adaptation or resilience of farming systems in the face of environmental disruptions. From Northern Senegal to Southern Benin, the research group explores a wide range of ecoregions and socio-ecological contexts, including stakeholders and their objectives, land use and agricultural practices, and management of biodiversity for enhancing biological control. Main challenges to be turned into opportunities include (i) encouraging collaborations amongst researchers from different scientific fields, (ii) fostering interactive research and synergies among research institutions and among countries, and (iii) developing an ecological engineering approach for the design of sustainable agricultural systems for smallholder farmers.
Uploads
Papers by Valérie Soti