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Papers by sory cisse

Research paper thumbnail of Etude des conditions et du seuil de grégarisation du Criquet pélerin, Schistocerca gregaria Forskäl (Orthoptera, Acrididae), dans son aire de reproduction en Mauritanie occidentale

The Desert locust, Schistocerca gregaria (Forskal 1775) (Orthoptera: Acrididae), is a major pest ... more The Desert locust, Schistocerca gregaria (Forskal 1775) (Orthoptera: Acrididae), is a major pest in several parts of the world mainly because of its ability to gregarize causing significant damage to crop and pasture within large geographical areas. The preventive control strategy adopted by locust affected countries is focused on early warning and early reaction system which is assumed as a way to decrease the frequency of plagues by monitoring and controlling population's size in seasonal breeding areas. The work presented here was to elucidate the density threshold and the conditions that promote Desert locust's gregarization under natural conditions in western Mauritania. Indeed, the density threshold of gregarization remains a major tool in determining intervention criteria for minimizing the locust invasion risks. Paradoxically, this one remains less documented. Also, the influence of environmental factors on the gregarization phenomenon has been poorly studied, particularly in the field, because of the complexity of involved parameters in this process. The currently density thresholds for gregarization used in locust control have been only empirically assumed. These have never been tested in the field. The study was conducted in three parallel tracks. The first track involved detailing analysis of historical data of Desert locust survey operations of National Center for Locust Control in Mauritania. Hence, the information recorded in database was used to examine the influence of the locust adult's density and vegetation on the probability of observing gregarious populations. Then, the second track was needed because of the weakness of records of hoppers densities information in the database. The latter was performed during two successive rainy seasons allowing field sampling in seasonal breeding areas of Mauritania. Accordingly, this track permitted an assessment of Desert locust hoppers density thresholds of gregarization in field conditions. The final track was focused on laboratory study for characterizing behavioral phase in Desert locust hopper with spatial distribution analysis in the arena. It was intended to develop a simple diagnostic tool that could be used in the field to determine the behavioural phase state of locust populations. Establishing the phase states from behavioural analysis methodology was expected to discuss the credibility of empirical sampling method which was used in previous axes. The results showed that the lowering of suitable habitat due to gradual vegetation drying accelerates locust adults (winged) crowding. Thus, it has been demonstrated in detail the change in the density threshold of gregarization as function of habitat heterogeneity. Low and dry vegetation cover showed a lower gregarization threshold, in contrast dense and green VII vegetation cover favored locust dispersion with a higher gregarization threshold. In addition, the obtained results with field sampling which highlighted the fundamental role of hopper density in gregarization process and allowed successful assessment of the vegetation factors involvement level in inhibition or promotion of phase change process. Moreover, the used of behavioral arena was successful in characterizing phase behavior in Desert Locust. The method was able to detect the behavioral phase of a group of locusts from the spatial distribution mode analysis. The reliability of these results verified the strength of the empirical method of phase assessment on field. This tool allowed establishing an analogy with the empirical sampling method of locust behaviour that is usually focused on appearance (colour and behaviour). The methodology has also been successfully implemented in nature during fieldwork in second track.

Research paper thumbnail of Research on the Comparison between the Different Policies by Service Level and Inventory Level Performance of Auto Parts in N.A.C.C. (North Automobile Components Company)

Journal of Management Science & Engineering Research

As after sales services become more and more popular, particularly preventive or corrective maint... more As after sales services become more and more popular, particularly preventive or corrective maintenance, the intervention and repair of the customer’s goods in a timely and efficient manner ensure customer satisfaction and contribute to the establishment of brand image in the market of the suppliers. The availability and quality of spare parts are key elements of this strategy while ensuring minimal management costs. The reuse of spare parts retrieved from customer systems is a growing maintenance strategy practice which impacts the traditional spare parts supply chain. This reuse is primarily driven by extending the economic life of goods, initially regarded as waste and therefore without added value, by transforming them into valuable spare parts that can be reused; secondly, for environmental or regulatory reasons, demanding responsibility for the treatment of products at the end of their life; and thirdly, to improve the availability of parts for maintenance, especially parts th...

Research paper thumbnail of Mapping the spatiotemporal distributions of the Desert Locust in Mauritania and Morocco to improve preventive management

Basic and Applied Ecology, 2017

Understanding Desert Locust population dynamics is a prerequisite for the implementation of a pre... more Understanding Desert Locust population dynamics is a prerequisite for the implementation of a preventive management strategy against its invasions. The present study aims to describe these dynamics through conducting probability analyses of locust presence in time and space. Historical data from field surveys conducted by management teams in Mauritania and Morocco for the period 1988-2015 were used. Temporal smoothing and spatio-temporal extrapolations were performed on a monthly basis. We established monthly probability maps of locust observation following two scenarios: recession period (mainly solitarious phase) and invasion period (mainly gregarious phase). Also, observation probability maps of hoppers or mature adults allowed the identification of seasonal breeding areas. The methodology highlights the potentially favourable areas to be monitored every year. It also highlights the lack of information in some areas of the two countries. We observed that the seasonal survey process during recession periods follow the seasonal pattern of gregarious invasions. We argue that this is the result of climatic conditions related to the oscillation of the intertropical convergence zone. However, we advise that these similar yearly cycles should not hinder surveys in recession periods to be conducted in places not receiving swarms during invasion periods. Nevertheless, we conclude that these maps should be helpful for planning the preparation of survey teams in the field. This will reduce survey operation costs and decrease invasion risks.

Research paper thumbnail of Soil moisture from remote sensing to forecast desert locust presence

Journal of Applied Ecology, 2019

1. Preventive control of desert locusts is based on monitoring recession areas to detect outbreak... more 1. Preventive control of desert locusts is based on monitoring recession areas to detect outbreaks. Remote sensing has been increasingly used in the preventive control strategy. Soil moisture is a major ecological driver of desert locust populations but is still missing in the current imagery toolkit for preventive management. Accepted Article This article is protected by copyright. All rights reserved. 5. Implications pour les politiques publiques : Nous recommandons l'utilisation opérationnelle des estimations d'humidité du sol à 1 km de résolution dans la lutte préventive contre le criquet pèlerin. Quand l'humidité du sol augmente dans une zone aride d'habitat potentiel du criquet pèlerin, des prospections acridiennes devraient être conduites dans les deux mois suivants afin d'évaluer le besoin d'effectuer d'autres mesures préventives. L'humidité du sol estimée par télédétection pourrait aussi être utile dans la gestion intégrée d'autres ravageurs des cultures.

Research paper thumbnail of Daily microhabitat shifting of solitarious-phase Desert locust adults: implications for meaningful population monitoring

Research paper thumbnail of Effect of vegetation on density thresholds of adult desert locust gregarization from survey data in Mauritania

Entomologia Experimentalis et Applicata, 2013

ABSTRACT In the desert locust, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae), the thres... more ABSTRACT In the desert locust, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae), the threshold density inducing the gregarization phenomenon has never been determined under natural conditions. The influence of environmental factors on this phenomenon has been studied mostly in controlled environments. Based on data collected during several years by the survey teams of the National Center for Locust Control in Mauritania, we analyzed the influence of locust density, vegetation cover, and vegetation status on the probability of observing gregarious locusts. We assumed that a probability to observe gregarious locusts of 0.5 corresponded to the density threshold of gregarization. The results showed in detail the change in the threshold of gregarization according to the cover and status of the vegetation. Low cover and dry vegetation led to a low density threshold of gregarization probably due to high probability of individuals to touch each other. Dense and green vegetation favored a high threshold of gregarization probably due to a dispersion of the individuals and a low probability of individual encounters. These findings should help the management of locusts and decision making during control operations.

Research paper thumbnail of Estimation of density threshold of gregarization of desert locust hoppers from field sampling in Mauritania

Entomologia Experimentalis et Applicata, 2015

For desert locusts, Schistocerca gregaria (Forsk al) (Orthoptera: Acrididae), the hopper density ... more For desert locusts, Schistocerca gregaria (Forsk al) (Orthoptera: Acrididae), the hopper density threshold of gregarization remains poorly documented. Field sampling was carried out in traditional seasonal breeding areas of Mauritania during two successive years without invasion to approximate the gregarization threshold. Hopper densities were assessed at numerous sampling sites. Vegetation was also sampled to characterize the habitats. Hopper behavior was analyzed in situ with the help of a behavioral circular arena to test our assumptions on empirical locust phases determination based on physical appearance (coloration and behavior) following FAO guidelines. The results provided a critical density value around 2.45 hoppers m À2 , above which gregarious hoppers were expected to be seen more frequently in nature. Hopper density was confirmed as the main factor explaining the presence of gregarious individuals. The level of involvement of vegetation parameters such as plant density, basal area, volume, distance between plants, greenness, or combinations of these indicators was low in explaining the observation of gregarious hoppers compared with hopper density. Vegetation cover and height were the only vegetation characteristics that could enhance the prediction of phase status with hopper density. The hoppers' phase determined from their behavior observed in the arena was similar to that characterized through FAO guidelines phase assessment, making consistent the field sampling method. Additionnally, the use of this arena illustrated that the grouping behavior of hoppers is a gradual response to density. This study can be seen as a step forward in the estimation of hopper density thresholds of gregarization in the field. This should improve the decision making for intervention during preventive control operations.

Research paper thumbnail of Characterizing phase-related differences in behaviour of Schistocerca gregaria with spatial distribution analysis

Entomologia Experimentalis et Applicata, 2015

The behaviour of locusts has been studied extensively using two approaches: (1) analysing a singl... more The behaviour of locusts has been studied extensively using two approaches: (1) analysing a single individual's response to a group stimulus or (2) using group conditions to look at aggregation patterns. The second approach has, in contrast with the first one, not been improved in terms of statistical analyses since the 1960s. In the present study, we propose a spatial statistics approach of point-pattern analysis to improve the group-based assessment of behavioural phase characterization. This diagnostic tool was developed and tested in the laboratory with comparative analysis of solitarious (isolation-reared) and gregarious (crowd-reared) desert locusts, Schistocerca gregaria (Forsk al) (Orthoptera: Acrididae). The spatial distribution patterns of 10 either solitarious or gregarious thirdinstar hoppers were characterized with nearest neighbour distance measurements in a circular arena. The temporal sequence of spatial disposition of locusts was recorded with a digital camera taking photographs at regular intervals. The approach of point-pattern analysis focused on the spatial distribution of observed events and allowed us to make inferences about the underlying process that generated them. The results confirmed that our diagnostic tool could identify that crowd-reared hoppers tended to aggregate more to conspecifics than isolation-reared ones. We could also verify that isolation-reared hoppers were less active than crowd-reared ones, but this was only true at the beginning of the experiments. The spatial statistics approach proposed in the present study could help with observations of phase-related differences in the behaviour of locusts.

Research paper thumbnail of Study on Customer Demand Forecasting Models, Stock Management, Classification and Policies for Automobile Parts Manufacturing Company N.A.C.C. (An Advance on Classical Models)

Journal of Management Science & Engineering Research

The primary intent of the current research is to provide insights regarding the management of spa... more The primary intent of the current research is to provide insights regarding the management of spare parts within the supply chain, in conjunction with offering some methods for enhancing forecasting and inventory management. In particular, to use classical forecasting methods, the use of weak and unstable demand is not recommended. Furthermore, statistical performance measures are not involved in this particular context. Furthermore, it is expected that maintenance contracts will be aligned with different levels. In addition to the examination of some literature reviews, some tools will guide us through this process. The article proposes new performance analysis methods that will help integrate inventory management and statistical performance while considering decision maker priorities through the use of different methodologies and parts age segmentation. The study will also identify critical level policies by comparing different types of spenders according to the inventory manageme...

Research paper thumbnail of Etude des conditions et du seuil de grégarisation du Criquet pélerin, Schistocerca gregaria Forskäl (Orthoptera, Acrididae), dans son aire de reproduction en Mauritanie occidentale

The Desert locust, Schistocerca gregaria (Forskal 1775) (Orthoptera: Acrididae), is a major pest ... more The Desert locust, Schistocerca gregaria (Forskal 1775) (Orthoptera: Acrididae), is a major pest in several parts of the world mainly because of its ability to gregarize causing significant damage to crop and pasture within large geographical areas. The preventive control strategy adopted by locust affected countries is focused on early warning and early reaction system which is assumed as a way to decrease the frequency of plagues by monitoring and controlling population's size in seasonal breeding areas. The work presented here was to elucidate the density threshold and the conditions that promote Desert locust's gregarization under natural conditions in western Mauritania. Indeed, the density threshold of gregarization remains a major tool in determining intervention criteria for minimizing the locust invasion risks. Paradoxically, this one remains less documented. Also, the influence of environmental factors on the gregarization phenomenon has been poorly studied, particularly in the field, because of the complexity of involved parameters in this process. The currently density thresholds for gregarization used in locust control have been only empirically assumed. These have never been tested in the field. The study was conducted in three parallel tracks. The first track involved detailing analysis of historical data of Desert locust survey operations of National Center for Locust Control in Mauritania. Hence, the information recorded in database was used to examine the influence of the locust adult's density and vegetation on the probability of observing gregarious populations. Then, the second track was needed because of the weakness of records of hoppers densities information in the database. The latter was performed during two successive rainy seasons allowing field sampling in seasonal breeding areas of Mauritania. Accordingly, this track permitted an assessment of Desert locust hoppers density thresholds of gregarization in field conditions. The final track was focused on laboratory study for characterizing behavioral phase in Desert locust hopper with spatial distribution analysis in the arena. It was intended to develop a simple diagnostic tool that could be used in the field to determine the behavioural phase state of locust populations. Establishing the phase states from behavioural analysis methodology was expected to discuss the credibility of empirical sampling method which was used in previous axes. The results showed that the lowering of suitable habitat due to gradual vegetation drying accelerates locust adults (winged) crowding. Thus, it has been demonstrated in detail the change in the density threshold of gregarization as function of habitat heterogeneity. Low and dry vegetation cover showed a lower gregarization threshold, in contrast dense and green VII vegetation cover favored locust dispersion with a higher gregarization threshold. In addition, the obtained results with field sampling which highlighted the fundamental role of hopper density in gregarization process and allowed successful assessment of the vegetation factors involvement level in inhibition or promotion of phase change process. Moreover, the used of behavioral arena was successful in characterizing phase behavior in Desert Locust. The method was able to detect the behavioral phase of a group of locusts from the spatial distribution mode analysis. The reliability of these results verified the strength of the empirical method of phase assessment on field. This tool allowed establishing an analogy with the empirical sampling method of locust behaviour that is usually focused on appearance (colour and behaviour). The methodology has also been successfully implemented in nature during fieldwork in second track.

Research paper thumbnail of Research on the Comparison between the Different Policies by Service Level and Inventory Level Performance of Auto Parts in N.A.C.C. (North Automobile Components Company)

Journal of Management Science & Engineering Research

As after sales services become more and more popular, particularly preventive or corrective maint... more As after sales services become more and more popular, particularly preventive or corrective maintenance, the intervention and repair of the customer’s goods in a timely and efficient manner ensure customer satisfaction and contribute to the establishment of brand image in the market of the suppliers. The availability and quality of spare parts are key elements of this strategy while ensuring minimal management costs. The reuse of spare parts retrieved from customer systems is a growing maintenance strategy practice which impacts the traditional spare parts supply chain. This reuse is primarily driven by extending the economic life of goods, initially regarded as waste and therefore without added value, by transforming them into valuable spare parts that can be reused; secondly, for environmental or regulatory reasons, demanding responsibility for the treatment of products at the end of their life; and thirdly, to improve the availability of parts for maintenance, especially parts th...

Research paper thumbnail of Mapping the spatiotemporal distributions of the Desert Locust in Mauritania and Morocco to improve preventive management

Basic and Applied Ecology, 2017

Understanding Desert Locust population dynamics is a prerequisite for the implementation of a pre... more Understanding Desert Locust population dynamics is a prerequisite for the implementation of a preventive management strategy against its invasions. The present study aims to describe these dynamics through conducting probability analyses of locust presence in time and space. Historical data from field surveys conducted by management teams in Mauritania and Morocco for the period 1988-2015 were used. Temporal smoothing and spatio-temporal extrapolations were performed on a monthly basis. We established monthly probability maps of locust observation following two scenarios: recession period (mainly solitarious phase) and invasion period (mainly gregarious phase). Also, observation probability maps of hoppers or mature adults allowed the identification of seasonal breeding areas. The methodology highlights the potentially favourable areas to be monitored every year. It also highlights the lack of information in some areas of the two countries. We observed that the seasonal survey process during recession periods follow the seasonal pattern of gregarious invasions. We argue that this is the result of climatic conditions related to the oscillation of the intertropical convergence zone. However, we advise that these similar yearly cycles should not hinder surveys in recession periods to be conducted in places not receiving swarms during invasion periods. Nevertheless, we conclude that these maps should be helpful for planning the preparation of survey teams in the field. This will reduce survey operation costs and decrease invasion risks.

Research paper thumbnail of Soil moisture from remote sensing to forecast desert locust presence

Journal of Applied Ecology, 2019

1. Preventive control of desert locusts is based on monitoring recession areas to detect outbreak... more 1. Preventive control of desert locusts is based on monitoring recession areas to detect outbreaks. Remote sensing has been increasingly used in the preventive control strategy. Soil moisture is a major ecological driver of desert locust populations but is still missing in the current imagery toolkit for preventive management. Accepted Article This article is protected by copyright. All rights reserved. 5. Implications pour les politiques publiques : Nous recommandons l'utilisation opérationnelle des estimations d'humidité du sol à 1 km de résolution dans la lutte préventive contre le criquet pèlerin. Quand l'humidité du sol augmente dans une zone aride d'habitat potentiel du criquet pèlerin, des prospections acridiennes devraient être conduites dans les deux mois suivants afin d'évaluer le besoin d'effectuer d'autres mesures préventives. L'humidité du sol estimée par télédétection pourrait aussi être utile dans la gestion intégrée d'autres ravageurs des cultures.

Research paper thumbnail of Daily microhabitat shifting of solitarious-phase Desert locust adults: implications for meaningful population monitoring

Research paper thumbnail of Effect of vegetation on density thresholds of adult desert locust gregarization from survey data in Mauritania

Entomologia Experimentalis et Applicata, 2013

ABSTRACT In the desert locust, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae), the thres... more ABSTRACT In the desert locust, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae), the threshold density inducing the gregarization phenomenon has never been determined under natural conditions. The influence of environmental factors on this phenomenon has been studied mostly in controlled environments. Based on data collected during several years by the survey teams of the National Center for Locust Control in Mauritania, we analyzed the influence of locust density, vegetation cover, and vegetation status on the probability of observing gregarious locusts. We assumed that a probability to observe gregarious locusts of 0.5 corresponded to the density threshold of gregarization. The results showed in detail the change in the threshold of gregarization according to the cover and status of the vegetation. Low cover and dry vegetation led to a low density threshold of gregarization probably due to high probability of individuals to touch each other. Dense and green vegetation favored a high threshold of gregarization probably due to a dispersion of the individuals and a low probability of individual encounters. These findings should help the management of locusts and decision making during control operations.

Research paper thumbnail of Estimation of density threshold of gregarization of desert locust hoppers from field sampling in Mauritania

Entomologia Experimentalis et Applicata, 2015

For desert locusts, Schistocerca gregaria (Forsk al) (Orthoptera: Acrididae), the hopper density ... more For desert locusts, Schistocerca gregaria (Forsk al) (Orthoptera: Acrididae), the hopper density threshold of gregarization remains poorly documented. Field sampling was carried out in traditional seasonal breeding areas of Mauritania during two successive years without invasion to approximate the gregarization threshold. Hopper densities were assessed at numerous sampling sites. Vegetation was also sampled to characterize the habitats. Hopper behavior was analyzed in situ with the help of a behavioral circular arena to test our assumptions on empirical locust phases determination based on physical appearance (coloration and behavior) following FAO guidelines. The results provided a critical density value around 2.45 hoppers m À2 , above which gregarious hoppers were expected to be seen more frequently in nature. Hopper density was confirmed as the main factor explaining the presence of gregarious individuals. The level of involvement of vegetation parameters such as plant density, basal area, volume, distance between plants, greenness, or combinations of these indicators was low in explaining the observation of gregarious hoppers compared with hopper density. Vegetation cover and height were the only vegetation characteristics that could enhance the prediction of phase status with hopper density. The hoppers' phase determined from their behavior observed in the arena was similar to that characterized through FAO guidelines phase assessment, making consistent the field sampling method. Additionnally, the use of this arena illustrated that the grouping behavior of hoppers is a gradual response to density. This study can be seen as a step forward in the estimation of hopper density thresholds of gregarization in the field. This should improve the decision making for intervention during preventive control operations.

Research paper thumbnail of Characterizing phase-related differences in behaviour of Schistocerca gregaria with spatial distribution analysis

Entomologia Experimentalis et Applicata, 2015

The behaviour of locusts has been studied extensively using two approaches: (1) analysing a singl... more The behaviour of locusts has been studied extensively using two approaches: (1) analysing a single individual's response to a group stimulus or (2) using group conditions to look at aggregation patterns. The second approach has, in contrast with the first one, not been improved in terms of statistical analyses since the 1960s. In the present study, we propose a spatial statistics approach of point-pattern analysis to improve the group-based assessment of behavioural phase characterization. This diagnostic tool was developed and tested in the laboratory with comparative analysis of solitarious (isolation-reared) and gregarious (crowd-reared) desert locusts, Schistocerca gregaria (Forsk al) (Orthoptera: Acrididae). The spatial distribution patterns of 10 either solitarious or gregarious thirdinstar hoppers were characterized with nearest neighbour distance measurements in a circular arena. The temporal sequence of spatial disposition of locusts was recorded with a digital camera taking photographs at regular intervals. The approach of point-pattern analysis focused on the spatial distribution of observed events and allowed us to make inferences about the underlying process that generated them. The results confirmed that our diagnostic tool could identify that crowd-reared hoppers tended to aggregate more to conspecifics than isolation-reared ones. We could also verify that isolation-reared hoppers were less active than crowd-reared ones, but this was only true at the beginning of the experiments. The spatial statistics approach proposed in the present study could help with observations of phase-related differences in the behaviour of locusts.

Research paper thumbnail of Study on Customer Demand Forecasting Models, Stock Management, Classification and Policies for Automobile Parts Manufacturing Company N.A.C.C. (An Advance on Classical Models)

Journal of Management Science & Engineering Research

The primary intent of the current research is to provide insights regarding the management of spa... more The primary intent of the current research is to provide insights regarding the management of spare parts within the supply chain, in conjunction with offering some methods for enhancing forecasting and inventory management. In particular, to use classical forecasting methods, the use of weak and unstable demand is not recommended. Furthermore, statistical performance measures are not involved in this particular context. Furthermore, it is expected that maintenance contracts will be aligned with different levels. In addition to the examination of some literature reviews, some tools will guide us through this process. The article proposes new performance analysis methods that will help integrate inventory management and statistical performance while considering decision maker priorities through the use of different methodologies and parts age segmentation. The study will also identify critical level policies by comparing different types of spenders according to the inventory manageme...