Agro-ecological Zones In Senegal Research Articles

Study of the Biodemographic Parameters of Two Genetically Distinct Strains of Callosobruchus maculatus from Two agroecological Zones of Senegal

During this study, we determined different biological parameters of Callosobruchus maculatus populations from two agro-ecological zones of Senegal (the ZSP and the ZVFS). To do this, strains of C. maculatus were collected in two localities, each representing an agro-ecological zone. The analysis of the results obtained shows that fecundity is greater for the strain coming from the silvopastoral zone (55.60 ± 19.144 eggs per female) than for that coming from the Senegal River valley zone (45 ± 18.577 eggs per female.). Furthermore, the evolution of egg laying shows that whatever the strain or population, more than 95% of eggs are laid during the first four days of the infestation with a peak on the second. In addition, the strains are characterized by an egg fertility rate exceeding 65% with a larval survival rate of over 75% and the Fouta strain has the highest rates. However, the emergence rate of the strain from the silvopastoral zone is lower at 49%. The longevity of adults in the Senegal River valley zone is significantly longer (11.035 ± 1.527 days) than that of adults in the silvopastoral zone. The sex ratio is in favor of males for both populations. The total development time and the oviposition-emergence time are relatively the same in the two strains with an average of 31 days and 21 days respectively.

INFLUENCE OF THE AGRO-ECOLOGICAL ZONES IN SENEGAL ON DIETARY CONSUMPTION OF PEANUT

Peanutisa valuable source of nutrients, but the patterns of peanut consumption, consumption frequencies and factors influencing peanut consumption in Senegal are poorly understood.This study surveyed the populations of four agroecological zones of Senegal:The Peanut Basin (BA), the Lower and Middle Casamance (BMC), the Eastern Senegal and Upper Casamance (SOHC) and the Senegal River Valley (VFS) with the aim of generating data on the consumption of peanut to fill this lack of knowledge and information on this food which represents a good part of the diet of the Senegalese population. The survey sampling plan is designed according to the principles of simple random sampling (SAS) combined with prior stratification. The results of the study showed that peanut-based dishes such as Nieleng in the BA use approximately 1048g of peanut during its preparation. In the VFS, the preparation of Dakhine requires an intake of 692g of peanut. The frequency of consumption of peanut-based dishes also varies according to agro-ecological zones. In the Peanut Basin, Mafe using approximately 465.7g per dish is consumed once or twice a week as is Mbaxalu Saloum in the BMC where 222.8g of peanut are used for a prepared dish. Individual peanut consumption varies depending on the agro-ecological zones. The highest average consumption is noted in the BA with 50.57g. It is followed by the SOHC, the VFS and the BMC with respective values of 41.38g, 25.18g. and 24.73g. People headed by a man in households consume an average of 50g of peanut per day per dish and those headed by a woman, around 40g.Polygamous families consume on average 55.4g of peanut per day per peanut dish. People in families whose chef did not attend school consume on average 51.6g of peanut per dish followed by those whose chef attended Koranic school with 50.9g of peanut per dish per day.

Climatic Anticipation of Dry Cereal Producers in the Groundnut Basin of Senegal

The Groundnut Basin is one of six agro-ecological zones in Senegal where farmers are very affected by climate uncertainty during the rainy season. This paper examines the types of climate anticipation of dry cereal producers before the start of the rainy season. The main parameter used to determine the types of anticipation is based on climate information. Farmers are characterized according to their ability to formulate a climate forecast from climate information sources for which they have a degree of confidence. The results show that the majority of farmers formulate adaptive expectations on the climate by defining a margin of error to the received information (35.41%), while only 1.65% makes expectations without a formal source. This study suggests that insurance policies should take into account the profile of farmers in the face of climatic information, in particular the level of tolerable loss anticipated by the producer and his other socio-economic characteristics, accessibility to basic social services and the production system practiced.

Genetic diversity and structure of Callosobruchus maculatus populations in the different agro-ecological zones of Senegal

The objective of this study is to determine the diversity and genetic structure of cowpea weevil populations in the different agro-ecological zones of Senegal. Thus, to achieve this objective, individuals of Callosobruchus maculatus from localities in each zone were used, after sampling and massive breeding. The sequenced gene is Cyt-B. The results showed high haplotypic diversity (0.901 ±0.00033) and low nucleotide diversity (0.010 ±0.0000003). These diversities studied by agro-ecological zone show that the Casamance zone has the greatest haplotypic diversity (0.901; P>0.05) while the eastern Senegal zone has the lowest value (0.439; P>0.05). The nucleotide diversity is lower in the Sylvo-pastoral zone (0.00112; P<0.05) and higher in the Casamance zone (0.01052; P<0.05). The genetic structuring shows that the Senegal River Valley-eastern Senegal zone couple is more differentiated [FST(Fixation index)]=0.70687; P<0.05) and the Casamance-Groundnut Basin zone couple is less differentiated (FST=0.21248; P<0.05). The greatest genetic distance was found between the Sylvo-pastoral zone and the River Valley and the smallest between the eastern Senegal zone and the River Valley. However, a significant genetic variation within the populations was noted (64.93%). Overall we have a low level of diversity and weakly structured populations except those of Tamba and Fouta. A slight influence of the zones was also noted.

Hexamermis sp. a potential candidate for the biological control of the fall armyworm in two agroecological zones of Senegal

Hexamermis sp. a potential candidate for the biological control of the fall armyworm in two agroecological zones of Senegal

The fall armyworm Spodoptera frugiperda (J.E. Smith), a new pest of maize in Africa: monitoring, damage evaluation and identification of natural enemies on production areas of Senegal

The fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith), an invasive pest of cereal crops in Africa, poses a real threat to food security in sub-Saharan African countries where cereals are the staple food. Since its appearance in Africa in 2016, the FAW has invaded almost all African countries due to its great dispersal capacity. Because of its resistance to a number of chemical pesticides but also the risks associated with the use of these, the search for an alternative method becomes essential. In order to report on the incidence of this pest and explore its associations with native natural enemies, a monitoring study of S. frugiperda populations, its damage as well as its natural enemies was carried out during the period of August to September 2020 in corn fields of two agro-ecological zones of Senegal and in the laboratory. Monitoring results show a heavy infestation with rates of up to nearly 75% of defoliated plants and more than 60% of attacked ears. The damage recorded remains low overall (score below 3/9). A wide range of auxiliary insects (17 families) made up of parasitoids and predators were identified in the field and in the laboratory as well as an endoparasitic nematode with a parasitism rate of 38.46% and a fungus in one of the sites. These results pave the way for the development of an approach to control CLA with these biological agents.

Anemia and intestinal parasites in farmers and family members and sheep in two agro-ecological zones in Senegal

The burden of anemia in Senegal is high, particularly in children and women in rural households. The main objectives of the study reported here were (i) to measure and compare the prevalence of anemia and intestinal parasitic infections in farmers and family members and sheep in two agro-ecological zones in Senegal and (ii) to examine the association between anemia and age or sex in farmers and family members. The study was conducted in Mpal (250 km from Dakar, the capital city) and Diawara (700 km from Dakar, a remote location near the Malian border). In humans, the prevalence of anemia was higher in Diawara (64/86 = 74%), compared to Mpal (13/29 = 45%) (p < 0.01). Using logistic regression, the odds of anemia were 20.3, 5.7, and 3.2 times higher in children 1–4 years old, children 5–12 years-old, and teenagers 13–19 years old, respectively, compared to adults 20–60 years old, after controlling for study site and sex (p < 0.05). In Diawara, the odds of anemia were 2.9 times higher in women, compared to men, after controlling for age (p = 0.06). The prevalence of intestinal parasites (Giardia sp.) was the same (7%) at both locations. In sheep, the prevalence of low packed cell volume (PCV) and low body condition was higher in Diawara (48/60 = 60% and 11/60 = 18%, respectively), compared to Mpal (23/46 = 50% and 0/46 = 0%, respectively) (p < 0.05). Clinical anemia was associated (p < 0.01) with low PCV and a positive diagnosis of H. contortus. Overall, the prevalence of anemia was higher in farmers and family members and owned sheep in Diawara. In addition, anemia was more common in children and women, an indication that intra-household food allocation may be regulated in favor of men and older age groups. The consequences of livestock affected with anemia and undernutrition can be significant. High morbidity and mortality in livestock can lead to low household income, inadequate household access to and individual consumption of animal source foods, and subsequent risk of anemia in children and women in rural households in Senegal.

Variability and genetic structuring of Sitophilus zeamais according to agroecological zones in Senegal (West of Africa)

Maize plays a socio-economic role in Senegal. However, it is considerably damaged by Sitophilus Zeamais, a beetle of the Curculionidae. Areas likely to favor the survival or extinction of Sitophilus zeamais can be identified because genetic diversity influences the adaptability of the individual. Our study aims to highlight a possible variation and structuring of Sitophilus zeamais according to five agroecological zones (AEZ) in Senegal, namely Nord Bassin Arachidier (NBA), Sud Bassin Arachidier (SBA), Sénégal Oriental Haute Casamance (SOHC), Basse Moyenne Casamance (BMC) and Zone Sylvo-Pastorale (ZSP). The purpose of this study is to reduce crop losses by recommending to farmers peas where the insect is reluctant to survive. So far, genetic studies on this insect have traced its phylogeny and its geographical distribution in Africa in general. Senegal has never been specifically studied. To achieve this goal, 89 individuals were captured in the 5 zones. The exploitation of the cytochrome B gene corresponding to these individuals revealed a high genetic diversity in the NBA, SBA, and SOHC and low in BMC and ZSP, but also a genetic structuring of the insect according to agroecological zones. Thus, the agroecological zones of the NBA, the SBA and the SOHC are favorable to its survival, while those of the BMC and the ZSP limit its expansion.

Current Status of Pearl Millet Downy Mildew Prevalence across Agroecological Zones of Senegal.

Pearl millet is a dominant staple cereal crop for smallholder farmers in Senegal. However, the crop is constrained by various nonbiotic and biotic stresses such as downy mildew disease. To assess the prevalence of this disease in Senegal, a field survey was conducted during the rainy season of 2017 across eight main pearl millet production regions following latitudinal gradient with different climatic conditions. Results showed that downy mildew prevalence was higher in Kaolack (incidence = 68.19%), Kaffrine (incidence = 77.19%), Tambacounda (incidence = 97.03%), Sedhiou (incidence = 82.78%), and Kolda (incidence = 98.01%) than Thies (incidence = 28.21%), Diourbel (incidence = 24.46%), and Fatick (incidence = 37.75%) regions. The field survey revealed an incidence as high as 98% and 28% of infected area in surveyed fields. Significant correlations between geographic coordinates, disease incidence, and infected areas were also observed. This study provided information that could help to understand the prevalence of downy mildew in pearl millet in Senegal.

Comparative Study of the Genetic Variability of Sitophilus Zeamais Subservient to 2 Host Plants (Millet and Maize) in Senegal (West Africa)

Millet and maize, because of the importance of their yields, constitute a reliable alternative to the question of sovereignty and food security. These cereals are exploited in all agroecological zones of Senegal. But their stocks, especially those of maize, are deteriorated by Sitophilus Zeamais, a beetle of the Curculionidae. It is therefore necessary to find natural solutions that are healthier than the use of pesticides which is harmful to living beings and the environment. This article makes a comparative study of the genetic diversity of the populations of this insect individually subservient to maize and to millet. The importance of this study is to find a genetic explanation for the differential vulnerability of these host plants to Sitophilus Zeamais, because the genetic diversity influences the adaptability of the individual and consequently its development. For this, insects Sitophilus Zeamais subservient on the one hand to maize and on the other hand to millet were collected in each agroecological zone. The exploitation of 125 sequences of the Cytochrome B gene corresponding to the individuals, by software of study in population genetics (Bioedit, DNAsp, Mega, Arlequin…) compared to parameters of genetic variability, revealed an approximately similar and high genetic diversity of the 2 populations of millet and maize. Thus, millet and maize genetically have the same effect on the adaptability of Sitophilus Zeamais.

Evidence of pathogenic variation in Sclerospora graminicola populations from pearl millet growing regions in Senegal

Downy mildew of pearl millet induced by Sclerospora graminicola is a major disease that causes significant yield losses in most pearl millet production areas worldwide. The pathogenic variability of S. graminicola populations from four agro-ecological zones in Senegal was assessed under field conditions. A set of 19 pearl millet lines, including 12 downy mildew-resistant differential lines with five improved cultivars and two local checks was evaluated during two consecutive rainy seasons (2015 and 2016) at Bambey, Nioro, Kolda and Sinthiou, representing the main pearl millet-growing zones of Senegal. Significant differences were observed among the tested lines, pathogen origin, year and their interactions for resistance to S. graminicola. Except for ICMR 356 and 7042 S, the downy mildew-resistant differential lines differed in their resistance to the pathogen from the four agro-ecological zones over the years, providing evidence that the S. graminicola isolates represented different races of the pathogen. Among the locations where the experiments were established, the highest average of downy mildew incidence over the two years was recorded at Nioro (18.7 ± 2.6%), Kolda (17.6 ± 1.8%) and Bambey (12.1 ± 2.3%), while the mean downy mildew incidence was lowest at Sinthiou (6.9 ± 2.9%). This finding indicated that populations of pathogen from Kolda, Nioro and Bambey are more virulent compared to the one from Sinthiou.

Genetic diversity of Jatropha curcas L. in Senegal compared with exotic accessions based on microsatellite markers

Significant efforts have been undertaken in West Africa to increase biofuel production with the expectation to alleviate the dependency on fossil energies and to reduce rural poverty by diversifying cultivated crops. In this context, Jatropha curcas L., a shrub belonging to Euphorbiaceae family, has gained great interest because of its oil which can be converted to biodiesel. It is also highly adaptable to marginal soils due to its drought-tolerant characteristics. Characterisation of J. curcas germplasm in Senegal could be an important input for its better management and in identifying genotypes that could be used in breeding program. Genetic diversity of 103 accessions including 82 accessions from different agro ecological zones in Senegal and 21 exotic accessions was assessed through 33 microsatellite markers. All the markers gave amplifications at the expected band size. Only one microsatellite marker, JCT17, was polymorphic showing 3 alleles and allows distinguishing 2 accessions from Burkina Faso. The surprisingly low level of genetic variation might be because introduction of J. curcas in Senegal seems to have been done from one or a few origins and the species has not regained genetic diversity since then due to vegetative propagation. Cultivation of J. curcas at large scale may face to vulnerability to pests and require many cautions. They are necessity to widen the genetic base of J. curcas in Senegal via new introductions from its centre of origin.

The role of climate forecasts in smallholder agriculture: Lessons from participatory research in two communities in Senegal

Climate forecasts have shown potential for improving resilience of African agriculture to climate shocks, but uncertainty remains about how farmers would use such information in crop management decisions and whether doing so would benefit them. This article presents results from participatory research with farmers from two agro-ecological zones of Senegal, West Africa. Based on simulation exercises, the introduction of seasonal and dekadal forecasts induced changes in farmers’ practices in almost 75% of the cases. Responses were categorized as either implying pure intensification of cropping systems (21% of cases), non-intensified strategies (31%) or a mix of both (24%). Among non-intensified strategies, the most common forecast uses are changes in sowing date and crop variety with the latter being more prevalent where a wider repertoire of varieties existed. Mixed strategies generally used more inputs like manure or chemical fertilizers coupled with another strategy such as changing sowing date. Yield estimates suggest that forecast use led to yield gains in about one-third of the cases, with relatively few losses. Impacts varied according to the nature of the actual rainy season, forecasts accuracy and the type of response, positive ones being higher in wetter years, with intensified strategies and with accurate predictions. These results validate prior evidence that climate forecasts may be able to help Senegalese farmers adapt to climate variability, especially helping them capitalize on anticipated favorable conditions. Realization of potential advantages appears associated with a context where there is greater varietal choice and options for intensification.

Genetic diversity of Tribolium castaneum (Herbst) population in storage infrastructures and agro ecological zones in Senegal

The stocks of millet are attacked by the beetle among them T. castaneum. This devastator attacks the grain and causes important losses as for as the stocks of ground millet in the sahel. The aim of this study is to evaluate genetic diversity of T. castaneum population meet in the stocking infrastructures and the different agroecological areas with the intention to identify the different haplotypes that walk around. Portions of the cytochrome b and 28S ribosomal genes of T. castaneum were sequenced, using samples from that represent storage infrastructures and agroecological areas in Senegal. The results reveal a strong haplotype diversity in the stores of Sandiara (0.889±0.127) and Diaroume (0.556±0.165). The population of T. castaneum meet in the stores who supply themselves locally as that of Djilas show a weak haplotypique and nucleotidic diversity. The cereals marketing at the markets such as the Sandiara one would be at the origine of the wealth haplotypic observed in the store taken as an exemple in this locality. The pourcentage (0.16%) of molecular variance analysis (AMOVA) shows that there is not a significant genetic differentiation between agroecological areas. The test of Mantel shows that there is no correlation between geographical distance and genetic differenciation.

Aspergillus Colonization and Aflatoxin Contamination of Maize and Sesame Kernels in Two Agro-ecological Zones in Senegal

Aflatoxin contamination of major food crops is a serious problem in Senegal. Maize and sesame samples were collected during a survey in five districts located in two agro-ecological zones in Senegal to determine levels of aflatoxin contamination and the distribution and toxigenicity potential of members of Aspergillus section Flavi. Maize samples from the Guinea Savannah zone (SG) exhibited lower aflatoxin content and colony-forming units (cfu) than those collected from the Sudan Savannah (SS) zone. In maize, aflatoxin concentration and cfu of A.flavus varied with cultivars, shelling practices and storage methods. The maize variety 'Jaune de Bambey' had high aflatoxin levels in both agro-ecological zones. Aflatoxin content in machine-shelled maize (120 ng/g) was more than 10-fold higher than that in manually shelled (8 ng/g) or unshelled maize. Aflatoxin content (between 0.1 and 1.2 ng/g) and cfu values (between 13 and 42 000 cfu/g) of sesame were low, suggesting a low susceptibility to A. flavus. In both agro-ecological zones, and in all storage systems, aflatoxin contamination was lower in sesame than in maize. In this study, only three species of Aspergillus section Flavi (A. flavus, A. tamarii and the unnamed taxon S BG ) were observed with the frequency of toxigenic strains remaining below 50% in maize from the SG zone compared with 51% of isolates from samples collected in Sedhiou district in SS zone. The proportion of toxigenic strains isolated from sesame was variable. For both crops, L-strains were the most prevalent in the two agro-ecological zones. Some of the atoxigenic strains collected could be valuable microbial resources for the biological control of aflatoxin in Senegal.

Phylogenetic analyses of symbiotic genes and characterization of functional traits of Mesorhizobium spp. strains associated with the promiscuous species Acacia seyal Del.

To assess the phenotypic, symbiotic and genotypic diversity scope of Mesorhizobium spp. strains associated with Acacia seyal (Del.) isolated from different agro-ecological zones in Senegal, and uses of susceptible microbial inoculum in a reafforestation process. A polyphasic approach including phenotypic and genotypic techniques was used to study the diversity and their relationships with other biovars and species of rhizobia. The geographical origins of the strains have limited effect on their phylogenetic and phenotypic classification. Nodulation tests indicated promiscuity of the strains studied, because they were capable of nodulating six woody legume species (Acacia auriculiformis, Acacia senegal, A. seyal, Acacia tortilis ssp. raddiana, Leucaena leucocephala and Prosopis juliflora). Sequencing and phylogenetic analyses of nodA, nodC and nifH genes pointed out that in contrast to nodA gene, the phylogenies of nodC and nifH genes were not consistent with that of 16S rRNA, indicating that these genes of the A. seyal-nodulating rhizobia might have different origins. Microbial inoculation on nonsterile soil had significant effect on the nodules number and the growth of the seedlings, indicating that these strains of rhizobia might be used as inoculum. The results indicated that A. seyal is a nonselective host that can establish effective symbiosis with Mesorhizobium spp. strains from diverse genomic backgrounds and that the selected A. seyal-nodulating rhizobia could enhance plant growth. These results showed the important role that A. seyal could play in the improvement of reafforestation process as a promiscuous host, which can establish effective symbiosis with rhizobia from diverse genomic backgrounds.

Sequestration of carbon in soil organic matter in Senegal: an overview

Sequestration of Carbon in Soil Organic Matter ( SOCSOM) in Senegal is a multi-disciplinary development project planned and refined through two international workshops. The project was implemented by integrating a core of international experts in remote sensing, biogeochemical modeling, community socio-economic assessments, and carbon measurements in a fully collaborative manner with Senegal organizations, national scientists, and local knowledge and expertise. The study addresses the potential role developing countries in semi-arid areas can play in climate mitigation activities. Multiple benefits to smallholders could accrue as a result of management practices to re-establish soil carbon content lost because of land use changes or management practices that are not sustainable. The specific importance for the Sahel is because of the high vulnerability to climate change in already impoverished rural societies. The project focuses on four objectives in specific locations across the agroecological zones of Senegal. These objectives are: use of soil sampling and biogeochemical modeling to quantify the biophysical potential for carbon sequestration and to determine the sensitivity of the carbon stocks to various management and climate scenarios, to evaluate the socio-economic and cultural requirements necessary for successful project implementation directed toward an aggregation of smallholders to sequester around 100,000 t carbon (C), to support capacity building to develop a Carbon Specialist Team, and to initiate extrapolation from site-specific project areas to the Sahel region and the national level.

Variation in the biological n2 fixation by tree legumes in three ecological zones from the north to the south of Senegal

The utilization of N2‐fixing trees (NFTs) in agroforestry, in semiarid regions, is often limited by weak N2 fixation. This study was conducted to evaluate the N2‐fixing capacity of trees growing under natural conditions for 10 years with neither chemical fertilizer nor inoculum application. For this purpose, natural isotopic N abundance (δ15N) of leaves harvested from NFTs and reference plants (ref) growing in three agroecological zones of Senegal were analyzed. At each site (one site per zone), average δ45N ref was calculated N contents and δ15N values increased from the north in the Sudano‐Sahelian zone (Bambey and Nioro) to the south in the sub‐Guinean zone (Djibelor). The percentage of fixed N2 (%Ndfa) was low at both Bambey (Ndfa ≤ 22%) and Nioro (Ndfa ≤ 39%) and very high at Djibelor (76% δ≤ Ndfa δ≤. 95%). To explain the low levels of Ndfa observed at Bambey and Nioro, the hypothesis of lack of Bradyrhizobium strains in these soils was made. This hypothesis was confirmed by results obtained from a trial conducted under controlled conditions, which showed absence of nodulation on Gliricidia sepium growing under optimal conditions of water and nutrient supply. Improvement of N2 fixation of NFTs in the semiarid zone is a prerequisite for implementation of sustainable agroforestry systems.