Minimal tillage and intermittent flooding farming systems show a potential reduction in the proliferation of Anopheles mosquito larvae in a rice field in Malanville, Northern Benin.

BACKGROUND: Irrigation systems have been identified as one of the factors promoting malaria disease around agricultural farms in sub-Saharan Africa. However, if improved water management strategy is adopted during rice cultivation, it may help to reduce malaria cases among human population living around rice fields. This study aimed to assess the impact of the different irrigation practices on malaria transmission, as well as to evaluate the water management system that will best mitigate malaria transmission in Malanville, Benin. METHODS: Knowledge, Attitude and Practice (KAP) study was conducted on 104 households staying on and around the rice fields in Malanville. The study focused on the frequency of mosquito bites and preventive measures against malaria as well as soil preparation and rice planting methods. Mosquito larvae density was assessed in different water management system: continuous flooding (CF) or intermittent flooding (IF), deep tillage (DT) or minimal tillage (MT) and normal levelling (NL) or abnormal levelling (AL) in an experimental hut set-up. Larvae were collected using dipping methods and their density was determined. RESULTS: Three tillage systems, which include the use of tiller, plow and hoe, were identified on the rice field. Continuous flooding was the only irrigation system used by farmers. Retrospective data from Malanville Health Centre revealed higher malaria cases during rice production season, which was also confirmed by field participants. The density of Anopheles larvae was reduced by 80.8%, 30.8% and 40.7% (P = 0.000) during transplanting, tillering and maturation periods, respectively with intermittent flooding compared to continuous flooding. In addition, a clear reduction of larva density was observed with both intermittent flooding systems applied to minimal tillage (MT + IF + NL) and intermittent flooding applied to deep tillage (DT + IF + AL), showing that intermittent flooding could reduce the abundance of malaria vector in rice fields. CONCLUSION: Recommending intermittent flooding technology for rice cultivation may not only be useful for water management but could also be an intentional strategy to control mosquitoes vector-borne diseases around rice farms

Determination experimentale des principales caracteristiques physiques et mecaniques du bois du rônier (Borassus aethiopum mart.) d’origine Beninoise

Le rônier (Borassus aethiopum Mart.) est un palmier dont le bois est assez utilisé pour sa résistance mécanique et sa tenue aux intempéries dans les  constructions traditionnelles et même modernes en Afrique. Cependant, au Bénin et ailleurs, les connaissances sur les caractéristiques physiques et  mécaniques de l’espèce restent empiriques et non maîtrisées. Dans le présent travail, les caractéristiques physiques et mécaniques usuelles du  rônier originaire du sud-Bénin, sont déterminées. Il s’agit de la masse volumique basale, des taux de retraits totaux linéaire et volumique, du  module d’Young dans la direction du fil du bois en flexion quatre points ainsi que la contrainte de rupture en traction simple, en compression  simple, au cisaillement simple et en flexion quatre points.   Borassus aethiopum is a palm tree of which the wood is used enough for its mechanical resistance as well as for its resistance to natural harsh conditions, in old construction of housing in Benin. But  unfortunately, it is almost unknown as far as its scientific characteristics are concerned. Through the present research work, usual scientific parameters and characteristics of Borassus  palm wood from Benin, are determined. Specifically, infradensity, shrinkage coefficient and behaviour, breaking stress in the direction of the fibbers  at pulling, compression and bending, are known as well as Young modulus at bending. This knowledge will help for better use of Borassus palm  wood in the construction of housing

Chemical composition and seasonal variation of essential oil of Sclerocarya birrea (A. Rich.) Hochst subsp birrea leaves from Benin

Essential oils from fresh leaves of Sclerocarya birrea (A. Rich.) Hochst. were extracted by steam distillation. The oil yield from plant collected during the hot season (February) was 0.10±0.02 and 0.24±0.01% from plant collected during the cold season (August). GC/FID and GC/MS analysis allowed us to identify a total of 49 compounds, representing 98% of the hydrodistillate. The oils contained about 96% sesquiterpenes among which 38±0.034% of 7-epi-α-selinene during the hot season and 51.7±0.12% of 7-epi-α- selinene during the cold. The main components of the oil from the hot period were 7-epi-α-selinene (38±0.03%), α-muurolene (25±0.03%), valencene (17±0.06%), β-selinene (4.3±0.01), β-caryophyllene (3.2±0.02) allo-aromadendrene-epoxide (1.5±0.03) and 14-hydrox-α-humulene (1.5±0.03). The essential oil from the cold season was characterized by 7-epi-α-selinene (51.7±0.12%), β-selinene (15.1±0.2%), valencene (12.9±0.05%), α-selinene (8.1±0.03) and β-caryophyllene (1.8±0.02%). This is the first report of these components in the essential oil of Sclerocarya birrea

Farmers’ Perception of Climate Change and Climate-Smart Agriculture in Northern Benin, West Africa

Climate-Smart Agriculture (CSA) is an approach that identifies actions needed to transform and reorganize agricultural systems to effectively support agricultural development and ensure food security in the face of climate change. In this study, we assessed farmers’ perception of climate change, available CSA practices (CSAP) and the determinants of CSAP adoption in northern Benin. A list of CSAP was generated from a workshop with different stakeholders. Face-to-face interviews were then carried out with 368 farmers selected based on stratified random sampling in the study area. Binomial generalized mixed-effect models were run to analyze the relation between socio-demographic characteristics and the use of CSAP. CSAP were evaluated using a three-point Likert scale and the frequency of agreement with the statement that the selected practices meet the pillars of CSA. More than 60% of farmers had heard about climate change, and more than 80% had observed changes in temperature, rainfall amounts and distribution. Thirty-one CSAP were identified in the area, and only 11 were known by more than 50% of farmers. Out of the 12 selected CSAP for the assessment of adoption and evaluation, seven (7) were used by more than 50% of those who knew them. Farmers agreed with the statements that the evaluated practices improved farm productivity and adaptation to climate change but did not mitigate climate change. Ethnic group and education level were the two major factors that significantly determined the use of the evaluated CSAP

Farmers’ Perception of Climate Change and Climate-Smart Agriculture in Northern Benin, West Africa

Climate-Smart Agriculture (CSA) is an approach that identifies actions needed to transform and reorganize agricultural systems to effectively support agricultural development and ensure food security in the face of climate change. In this study, we assessed farmers’ perception of climate change, available CSA practices (CSAP) and the determinants of CSAP adoption in northern Benin. A list of CSAP was generated from a workshop with different stakeholders. Face-to-face interviews were then carried out with 368 farmers selected based on stratified random sampling in the study area. Binomial generalized mixed-effect models were run to analyze the relation between socio-demographic characteristics and the use of CSAP. CSAP were evaluated using a three-point Likert scale and the frequency of agreement with the statement that the selected practices meet the pillars of CSA. More than 60% of farmers had heard about climate change, and more than 80% had observed changes in temperature, rainfall amounts and distribution. Thirty-one CSAP were identified in the area, and only 11 were known by more than 50% of farmers. Out of the 12 selected CSAP for the assessment of adoption and evaluation, seven (7) were used by more than 50% of those who knew them. Farmers agreed with the statements that the evaluated practices improved farm productivity and adaptation to climate change but did not mitigate climate change. Ethnic group and education level were the two major factors that significantly determined the use of the evaluated CSAP

Densitometric HPTLC quantification of asiaticoside isolated from Centella asiatica (L.) Urb (Apiaceae) of Benin

Asiaticoside isolated from Centella asiatica has been found through in vitro test to serve as an active agent of healing on wounds. To quantify this compound in Centella asiatica cultivated in Benin, a new, simple and rapid High-Performance Thin-Layer Chromatography (HPTLC) method was developed and validated for its selectivity, its recovery, and its repeatability. Compounds have been separated on silica gel 60F254 plates with ethyl acetate/methanol/water (100/25/10, v/v/v), as mobile phase. The detection was done by densitometry scanning at λ = 600 nm and the calibration plots showed that the graphical response was linear and dependent on the quantity in the range of 2.50- 12.50 μg, with good values of R² = 0.998. This method is repeatable and precise with relative standard deviations between1.42 and 5.92% for the intra-day tests and between 1.27 and 6.57% for the inter-day tests for the quantities belonging to an interval of 2.50 and 12.50 μg. The limits of detection and quantification were 0.317 and 1.05 μg respectively. The quantity of asiaticoside found was 0.24% in the alcoholic extract

Seasonal variations of volatile constituents of Hemizygia bracteosa (Benth.) Briq. aerial parts from Benin

Essential oils from fresh aerial parts of Hemizygia bracteosa (Benth.) Briq. were extracted by steam distillation. The oil yield from plants collected during the hot season (February) and during the cold season (August) were 0.12 ± 0.01% and 0.25 ± 0.02%, respectively. GC/FID and GC/MS analyses allowed us to identify a total of 65 compounds, representing 97% of the hydrodistillate. The main components of the oil from the hot period were (E)-β-farnesene (64 ± 0.04%), β-elemene (7.4 ± 0.05%), trans-nerolidol (6.2 ± 0.04%), and α-muurolene (2.7 ± 0.03%). The essential oil from the cold season was characterized by the presence, as major compounds, of (E)-β-farnesene (67 ± 0.04%) along with β-caryophyllene (3.6 ± 0.06%), β-elemene (3.3 ± 0.05%), 7-epi-α-selinene (3.1 ± 0.01%) and p-cymene (2.5 ± 0.04%). This is the first report of these components in the essential oil of Hemizygia bracteosa (Benth.) Briq.[Variations saisonnières de constituants volatils de la partie aérienne de Hemizygia bracteosa (Benth.) Briq. du Bénin] Les huiles essentielles de parties aériennes fraîches de Hemizygia bracteosa (Benth.) Briq. ont été extraites par distillation à la vapeur. Les rendements en huile de la plante récoltée pendant la saison chaude (février) et la saison froide (août) étaient respectivement de 0,12 ± 0,01% et de 0,25 ± 0,02%. Les analyses GC/FID et GC/MS ont permis d'identifier 65 composés, représentant 97% de l'hydrodistillat. Les principaux composants de l'huile obtenue dans la période chaude étaient : (E)-β-farnésène (64 ± 0,04%), β-élémène (7,4 ± 0,05%), trans-nérolidol (6,2 ± 0,04%) et α-muurolène (2,7 ± 0,03%). L'huile essentielle de la saison froide est caractérisée par la présence, comme composés majoritaires, de (E)-β-farnésène (67 ± 0,04%), β-caryophyllène (3,6 ± 0,06%), β-élémène (3,3 ± 0,05%), 7-épi-α-selinène (3,1 ± 0,01%) et p-cymène (2,5 ± 0,04%). C'est la première observation de ces composants dans l'huile essentielle de Hemizygia bracteosa (Benth.) Briq

Chemical composition, in vitro antioxidant and antiparasitic properties of the essential oils of three plants used in traditional medicine in Benin.

Sclerocarya birrea (Sb), Psidium guajava (Pg) and Eucalyptus camaldulensis (Ec) are widely used in traditional medicine for the treatment of many diseases, some of which were related to oxidative stress and parasitic diseases. Their essential oils (EO) were analyzed by GC/MS and FID and tested in vitro for their antioxidant activities (DPPH), their anti-trypanosomal and anti-plasmodial activities against Trypanosoma brucei brucei (Tbb) (strain 427) and Plasmodium falciparum (Pf) (strain 3D7), respectively. Cytotoxicity was evaluated in vitro against CHO and WI38 cells (MTT) to evaluate the selectivity. They were shown to possess low antioxidant but a strong anti-trypanosomal and a good antiplasmodial activity with a good selectivity, except Ec oil whose anti-plasmodial activity was less interesting. Sb oil was the most active against Tbb(IC50 = 0.46 ± 0.28 µg/ml) and Pf (5.21 ± 1.12 µg/ml). All tested oils had low or no cytotoxicity against CHO and WI38 cells. GC/MS and GC/FID analysis revealed that composition of Sb (49 compounds) was characterised by the presence as main constituents of 7-epi-α-selinene, α-muurolene and valencene; Pg (60 compounds) by β-bisabolene, ar-curcumene and β-bisabolol; Ec (43 compounds) by γ-terpinene and p-cymene. The activity of these oils seems to be the result of a synergistic action of all their constituents, including minor ones. This study shows that essential oils of Sb and Pg can be good sources of anti-trypanosomal and anti-plasmodial agents

Chemical composition, cytotoxicity and in vitro antitrypanosomal and antiplasmodial activity of the essential oils of four Cymbopogon species from Benin.

ETHNOPHARMACOLOGICAL RELEVANCE: Cymbopogon species are largely used in folk medicine for the treatment of many diseases some of which related to parasitical diseases as fevers and headaches. As part of our research on antiparasitic essential oils from Beninese plants, we decided to evaluate the in vitro antiplasmodial and antitrypanosomal activities of essential oils of four Cymbopogon species used in traditional medicine as well as their cytotoxicity. MATERIALS AND METHODS: The essential oils of four Cymbopogon species Cymbopogon citratus (I), Cymbopogon giganteus (II), Cymbopogon nardus (III) and Cymbopogon schoenantus (IV) from Benin obtained by hydrodistillation were analysed by GC/MS and GC/FID and were tested in vitro against Trypanosoma brucei brucei and Plasmodium falciparum respectively for antitrypanosomal and antiplasmodial activities. Cytotoxicity was evaluated in vitro against Chinese Hamster Ovary (CHO) cells and the human non cancer fibroblast cell line (WI38) through MTT assay to evaluate the selectivity. RESULTS: All tested oils showed a strong antitrypanosomal activity with a good selectivity. Sample II was the most active against Trypanosoma brucei brucei and could be considered as a good candidate. It was less active against Plasmodium falciparum. Samples II, III and IV had low or no cytotoxicity, but the essential oil of Cymbopogon citraus (I), was toxic against CHO cells and moderately toxic against WI38 cells and needs further toxicological studies. Sample I (29 compounds) was characterised by the presence as main constituents of geranial, neral, beta-pinene and cis-geraniol; sample II (53 compounds) by the presence of trans-p-mentha-1(7),8-dien-2-ol, trans-carveol, trans-p-mentha-2,8-dienol, cis-p-mentha-2,8-dienol, cis-p-mentha-1(7),8-dien-2-ol, limonene, cis-carveol and cis-carvone; sample III (28 compounds) by beta-citronellal, nerol, beta-citronellol, elemol and limonene and sample IV (41 compounds) by piperitone, (+)-2-carene, limonene, elemol and beta-eudesmol. CONCLUSIONS: Our study shows that essential oils of Cymbopogon genus can be a good source of antitrypanosomal agents. This is the first report on the activity of these essential oils against Trypanosoma brucei brucei, Plasmodium falciparum and analysis of their cytotoxicity