Influence of Temperature and Storage Systems on Post-Harvest Losses of Maize Varieties Cultivated at Alibori in Northern Benin

Majority of post-harvest losses of several maize varieties observed in various storage systems in northern Benin are mainly caused by storage insects due to changes in climatic parameters. The objective of this study is to evaluate the levels of insect pest infestation of three maize varieties stored in storage systems at different temperature. In 18 villages at Alibori, maize farmers were surveyed through a participatory research approach and their storage structures were also visited. The temperature of all storage structures were noted. Weight loss of samples, numbers of Prostephanus truncates, Sitophilus zeamais and perforated grains were evaluated. In total, three maize varieties and three different groups of storage systems were identified during field observations. All the three maize varieties stored in the first storage systems group built with plants were less infested and had acceptable nutritional quality than the maize grains stored in the second group built in banco and third group built with tarpaulin. In these storage systems, the yellow maize variety was the most attacked, followed by the white maize variety and finally the mixed color of yellow and white maize variety the less attacked. Effective post-harvest management of stored products requires clear monitoring criteria of climatic parameters and effective implementation of abiotic and biotic factors

Hétérogénéité génétique et résistance des vecteurs du paludisme (Anopheles gambiae s.l) aux insecticides en zone cotonnière au Benin

La résistance des vecteurs du paludisme aux insecticides utilisés dans la lutte anti vectorielle est un obstacle majeur pour les programmes nationaux de lutte contre le paludisme. La présente étude avait pour but d’évaluer la diversité génétique des populations de Anopheles gambiae et la résistance aux insecticides (mutation Kdr et Ace-1) en zone cotonnière au Bénin. Deux méthodes de capture ont été utilisées pour la collecte d’échantillon. La capture sur appât humain et la récolte de la faune résiduelle matinale par spray. La PCR SINE a permis de distinguer deux espèces jumelles et d’obtenir les différents génotypes pour les deux gènes. Deux espèces du complexe An. gambiae s.l ont été trouvées en sympatrie (Anopheles coluzzii et Anopheles gambiae). La résistance kdr et Ace-1 connaissent un flux saisonnier. L’allèle résistant du gène kdr est fixé dans la population de vecteurs (Fis>0). Par contre, un déficit de l’allèle résistant est noté au niveau du gène Ace-1 (Fis<0).Mots clés : Hétérogénéité, génétique, résistance, vecteur, paludisme. English Title: Genetic heterogeneity and resistance to insecticides in malaria vector Anopheles gambiae s.l in the cotton growing area in Benin Resistance of malaria vectors to insecticides used in vector control is a major threat for national malaria control programs. The purpose of this study was to assess the genetic diversity of Anopheles gambiae populations and resistance to insecticides (Kdr Ace-1 mutation) in the cotton growing area in Benin. Two samples methods were used for mosquito collection: Human Landing catch (HLC) and the residual fauna collection by spray. The SINE PCR allow to identify species the different genotypes resistance genes. Two species of the An. gambiae s.l complex have been found in sympatry (Anopheles coluzzii and Anopheles gambiae). kdr and Ace-1 resistance had seasonal variation trend. The kdr resistance allele is fixed in the vector population (Fis> 0). Moreover, a deficit of the Ace-1 resistance allele was observed (Fis <0). Keywords: Heterogeneity, genetic, resistance, vector, malaria

Molecular basis of African yam domestication: Analyses of selection point to root development, starch biosynthesis, and photosynthesis related genes

Background: After cereals, root and tuber crops are the main source of starch in the human diet. Starch biosynthesis was certainly a significant target for selection during the domestication of these crops. But domestication of these root and tubers crops is also associated with gigantism of storage organs and changes of habitat. Results: We studied here, the molecular basis of domestication in African yam, Dioscorea rotundata. The genomic diversity in the cultivated species is roughly 30% less important than its wild relatives. Two percent of all the genes studied showed evidences of selection. Two genes associated with the earliest stages of starch biosynthesis and storage, the sucrose synthase 4 and the sucrose-phosphate synthase 1 showed evidence of selection. An adventitious root development gene, a SCARECROW-LIKE gene was also selected during yam domestication. Significant selection for genes associated with photosynthesis and phototropism were associated with wild to cultivated change of habitat. If the wild species grow as vines in the shade of their tree tutors, cultivated yam grows in full light in open fields. Conclusions: Major rewiring of aerial development and adaptation for efficient photosynthesis in full light characterized yam domestication. (Résumé d'auteur

Varietal diversity and conservation of cultivated yam (Dioscorea cayenensis, Dioscorea rotundata and Dioscorea alata) in Kara region (Togo)

L’igname est une culture stratégique au Togo. L’inventaire des variétés cultivées dans différents agro-éco-systèmes traditionnels permettent la sauvegarde et de ce patrimoine génétique ainsi que son utilisation dans des programmes de sélection. Des enquêtes ethno-botaniques ont été conduites dans 30 localités de la région de la Kara a permis de recenser 134 variétés: 122 de D. cayenensis-D. rotundata (57% précoces et 43 % tardives) et 12 de D. alata. La richesse variétale par localité varie de 7 à 30 variétés avec une moyenne de 19 ± 6 et une prédominance de D. cayenensis-D. rotundata. Dans 22% des localités, la diversité variétale a augmenté du fait des introductions (19 %) du Bénin (52 %), du Ghana (40 %) et du Nigeria (8 %). Les acquisitions variétales se font par achat (72 %), héritage (65 %), échange (45 %) et don (35 %). L’adoption d’une variété est déterminée par des critères agronomiques, commerciaux, technologiques, socio-culturels. Dans 78 % des localités, il y a une réduction de la diversité variétale du fait des pressions économiques, technologiques et sociales. 82 % des variétés sont faiblement distribuées et nécessitent une action urgente de conservation au champ. Cette conservation peut se faire dans 9 localités qui abritent 80 % de la richesse variétale totale. Mots clés: Ignames, perte de variétés, érosion génétique, conservation, Togo.  Yam is a strategic crop in Togo. Inventory and evaluation of cultivated varieties in different traditional agroeco-systems allows safeguard of this genetic heritage and its use in breeding programs. As welle ethnobotanical surveys were conducted in 30 localities of Kara region. The inventory allowed the recording 134 yam varieties distributed as follow 122 of D. cayenensis D. rotundata complex (57 % early varieties and 43 % late varieties) and 12 varieties of the type D. alata. The varietal richness by site varies betewen 7 and 30 with a predominance of D. cayenensis-D. rotundata. Varietal diversity has increased in 22 % of villages because of varietal introductions representing 19.2 % of the varieties. They come mainly from Bénin (52 %), Ghana (40 %) and Nigeria (8 %). The exchange (45 %), inheritance (65 %), the gift (72.5 %) and the purchase (35 %) are the varieties acquisition modes. In contrast to 78% of the localities there is a reduction of varietal diversity. Ten main factors mainly agronomic and social are the cause of the reduction. 83 % of the varieties are sparsely distributed and require urgent action on farm conservation because they are endangering. The storage may be done in 9 over the 30 localities that has about 80% of the varietal diversity.  Keywords: Yam, varieties loss, genetic erosion, conservation, Togo

Genetic Divergence in Northern Benin Sorghum ( Sorghum bicolor

Sorghum [Sorghum bicolor (L.) Moench] is an important staple food crop in northern Benin. In order to assess its diversity in Benin, 142 accessions of landraces collected from Northern Benin were grown in Central Benin and characterised using 10 qualitative and 14 quantitative agromorphological traits. High variability among both qualitative and quantitative traits was observed. Grain yield (0.72–10.57 tons/ha), panicle weight (15–215.95 g), days to 50% flowering (57–200 days), and plant height (153.27–636.5 cm) were among traits that exhibited broader variability. Correlations between quantitative traits were determined. Grain yield for instance exhibited highly positive association with panicle weight (r=0.901, P=0.000) and 100 seed weight (r=0.247, P=0.000). UPGMA cluster analysis classified the 142 accessions into 89 morphotypes. Based on multivariate analysis, twenty promising sorghum genotypes were selected. Among them, AT41, AT14, and AT29 showed early maturity (57 to 66 days to 50% flowering), high grain yields (4.85 to 7.85 tons/ha), and shorter plant height (153.27 to 180.37 cm). The results obtained will help enhancing sorghum production and diversity and developing new varieties that will be better adapted to the current soil and climate conditions in Benin

Diversity, Physicochemical and Technological Characterization of Elite Cassava ( Manihot esculenta

Cassava is one of the staple food crops contributing significantly to food and nutrition security in Benin. This study aimed to assess the diversity of the elite cassava cultivars of Bantè district, determine the physicochemical properties of the most preferred ones as well as the sensory attributes of their major derived products (gari and tapioca), and compare them with the farmers’ and processors’ perception on their technological qualities. The ethnobotanical investigation revealed existence of 40 cultivars including 9 elites that were further classified into three groups based on agronomics and technological and culinary properties. Clustered together, cultivars Idilèrou, Monlèkangan, and Odohoungbo characterized by low fiber content, high yield of gari and tapioca, and good in-ground postmaturity storage were the most preferred ones. Their physicochemical analysis revealed good rate of dry matters (39.8% to 41.13%), starch (24.47% to 25.5%) and total sugars (39.46% to 41.13%), low fiber (0.80% to 1.02%), and cyanide (50 mg/kg) contents. The sensory analysis of their gari and tapioca revealed very well appreciated (taste, color, and texture) products by the consumers. The confirmation by scientific analysis of the farmers’ perception on qualities of the most preferred cultivars indicated that they have good knowledge of their materials