Durabilité agro-écologique des exploitations agricoles dans la commune de Gogounou au Bénin

Cette recherche a pour objectif d’évaluer la durabilité agro-écologique de dix-neuf (19) exploitations agricoles de la commune de Gogounou au Nord Bénin. C’est une commune de grande production et des exploitations qui connaissent de grandes extensions de superficies cultivées avec l’introduction du matériel agricole du troisième niveau de la mécanisation agricole proposé par le programme de promotion de la mécanisation agricole. La méthode IDEA (Indicateurs de Durabilité des Exploitations Agricoles) de Vilain (2008), a été utilisée pour évaluer cette dimension de la durabilité. Les scores de durabilités, par indicateur puis par composante, déterminés avec les modalités proposées par la dite méthode, révèlent une bonne durabilité agro-écologique (avec un score de 74,3 / 100) des exploitations dans leur état actuel. Les composantes «diversité domestique» et «pratiques agricoles» contribuent fortement à ce niveau de durabilité alors que la composante «organisation de l’espace» constitue un facteur limitant. Par ailleurs, la mauvaise gestion des matières organiques cumulée à la facilité d’accès aux intrants chimiques (engrais et pesticides) ont négativement contribué aux scores de durabilité agro-écologiques. Limiter l’accès aux intrants chimiques et donc faciliter l’accès aux intrants compatibles à une agriculture durable seraient entre autres des leviers d’actions à envisager. L’évaluation de la durabilité agro-écologique de ces exploitations met en évidence les caractéristiques et pratiques agricoles favorables et défavorables qu’il faille, maximiser d’une part et, décourager d’autre part, pour éviter les situations extrêmes en matière de préservation de la diversité biologique et plus globalement d’agriculture durable.Mots-clés: indicateurs de durabilité, système de culture, mécanisation, Gogounou, Bénin. Agro-ecological sustainability of farms in the commune of Gogounou in BeninThis research aims to evaluate the agro-ecological sustainability of nineteen (19) were operating in the agricultural town Gogounou in northern Benin. It is a common high production and farm acreage experiencing exponential expansions grown with the introduction of agricultural machinery in the third level of agricultural mechanization offered by the promotion of agricultural mechanization program. The IDEA method (Agricultural Holdings Sustainability Indicators) Villain (2008), was used to assess this dimension of sustainability. Scores durabilities by indicator and by component, determined with the terms proposed by the method reveal good agro-ecological sustainability (with a score of 74.3 / 100) holdings in their current state. Components "domestic diversity" and "farming practices" contribute greatly to this level of durability while the component "space organization" is a limiting factor. In addition, poor management of cumulative organic matter to the ease of access to chemical inputs (fertilizers and pesticides) contributed negatively to agro-ecological sustainability scores. Limit access to chemical inputs and thus facilitate access to compatible inputs for sustainable agriculture would, among other actions levers to consider. The evaluation of the agro-ecological sustainability of these farms highlights the features and favorable and unfavorable farming practices that we should, on the one hand and maximize discourage other, to avoid extreme situations in preserving biodiversity and globally sustainable agriculture.Keywords: sustainability indicators, culture system, mechanization, Gogounou, Beni

Combining indoor residual spraying with chlorfenapyr and long-lasting insecticidal bed nets for improved control of pyrethroid-resistant Anopheles gambiae: an experimental hut trial in Benin.

BACKGROUND: Neither indoor residual spraying (IRS) nor long-lasting insecticidal nets (LLINs) are able to fully interrupt transmission in holoendemic Africa as single interventions. The combining of IRS and LLINs presents an opportunity for improved control and management of pyrethroid resistance through the simultaneous presentation of unrelated insecticides. METHOD: Chlorfenapyr IRS and a pyrethroid-impregnated polyester LLIN (WHO approved) were tested separately and together in experimental huts in southern Benin against pyrethroid resistant Anopheles gambiae and Culex quinquefasciatus. The bed nets were deliberately holed with either six or 80 holes to examine the effect of increasing wear and tear on protectiveness. Anopheles gambiae were genotyped for the kdr gene to assess the combination's potential to prevent the selection of pyrethroid resistance. RESULTS: The frequency of kdr was 84%. The overall mortality rates of An. gambiae were 37% and 49% with the six-hole and 80-hole LLINs, respectively, and reached 57% with chlorfenapyr IRS. Overall mortality rates were significantly higher with the combination treatments (82-83%) than with the LLIN or IRS individual treatments. Blood feeding (mosquito biting) rates were lowest with the 6-hole LLIN (12%), intermediate with the 80-hole LLIN (32%) and highest with untreated nets (56% with the 6-hole and 54% with the 80-hole nets). Blood feeding (biting) rates and repellency of mosquitoes with the combination of LLIN and chlorfenapyr IRS showed significant improvement compared to the IRS treatment but did not differ from the LLIN treatments indicating that the LLINs were the primary agents of personal protection. The combination killed significantly higher proportions of Cx. quinquefasciatus (51%, 41%) than the LLIN (15%, 13%) or IRS (32%) treatments. CONCLUSION: The chlorfenapyr IRS component was largely responsible for controlling pyrethroid-resistant mosquitoes and the LLIN component was largely responsible for blood feeding inhibition and personal protection. Together, the combination shows potential to provide additional levels of transmission control and personal protection against pyrethroid-resistant mosquitoes, thereby justifying the additional resources required. Chlorfenapyr has potential to manage pyrethroid resistance in the context of an expanding LLIN/IRS strategy

Chemical composition and insecticidal activity of plant essential oils from Benin against Anopheles gambiae (Giles)

BACKGROUND: Insecticide resistance in sub-Saharan Africa and especially in Benin is a major public health issue hindering the control of the malaria vectors. Each Anopheles species has developed a resistance to one or several classes of the insecticides currently in use in the field. Therefore, it is urgent to find alternative compounds to conquer the vector. In this study, the efficacies of essential oils of nine plant species, which are traditionally used to avoid mosquito bites in Benin, were investigated. METHODS: Essential oils of nine plant species were extracted by hydrodistillation, and their chemical compositions were identified by GC-MS. These oils were tested on susceptible “kisumu” and resistant “ladji-Cotonou” strains of Anopheles gambiae, following WHO test procedures for insecticide resistance monitoring in malaria vector mosquitoes. RESULTS: Different chemical compositions were obtained from the essential oils of the plant species. The major constituents identified were as follows: neral and geranial for Cymbopogon citratus, Z-carveol, E-p-mentha-1(7),8-dien-2-ol and E-p-mentha-2,8-dienol for Cymbopogon giganteus, piperitone for Cymbopogon schoenanthus, citronellal and citronellol for Eucalyptus citriodora, p-cymene, caryophyllene oxide and spathulenol for Eucalyptus tereticornis, 3-tetradecanone for Cochlospermum tinctorium and Cochlospermum planchonii, methyl salicylate for Securidaca longepedunculata and ascaridole for Chenopodium ambrosioides. The diagnostic dose was 0.77% for C. citratus, 2.80% for E. tereticornis, 3.37% for E. citriodora, 4.26% for C. ambrosioides, 5.48% for C. schoenanthus and 7.36% for C. giganteus. The highest diagnostic doses were obtained with S. longepedunculata (9.84%), C. tinctorium (11.56%) and C. planchonii (15.22%), compared to permethrin 0.75%. A. gambiae cotonou, which is resistant to pyrethroids, showed significant tolerance to essential oils from C. tinctorium and S. longepedunculata as expected but was highly susceptible to all the other essential oils at the diagnostic dose. CONCLUSIONS: C. citratus, E. tereticornis, E. citriodora, C. ambrosioides and C. schoenanthus are potential promising plant sources for alternative compounds to pyrethroids, for the control of the Anopheles malaria vector in Benin. The efficacy of their essential oils is possibly based on their chemical compositions in which major and/or minor compounds have reported insecticidal activities on various pests and disease vectors such as Anopheles

Study of the seroprevalence, associated risk factors and the haematological values of infected Chlamydia abortus small ruminants in Benin Republic

Chlamydia abortus is one of the causative agents. The aim of this study was to determine for the first time the serological prevalence and hematological parameters in small ruminants positive for Chlamydia abortus in Benin, mainly in the department of Ouémé. It covered five sites, namely Akpro-Missérété, Avrankou, Adjarra, Sèmè-Kpodji and Dangbo in the Ouémé department. A total of 385 sera (200 sheep and 185 goats) from subjects showing signs of reproductive loss were tested using the indirect Elisa method. Of the 385 sera tested, 30 (7,79%) were positive for Chlamydia abortus. Similarly, the blood of animals tested positive was analyzed for hematological parameters using Sysmex XN-Series automated blood analyzer. Different variations with significant differences in some hematological parameters of the red line and those of the white line, depending on the study sites, species, age and physiological stage of the animals (hemoglobin, mean corpuscular volume for the red line at the sites, lymphocytes and basophils for the white line at the sites; hemoglobin for the red lineage and lymphocytes for the white lineage at species level; lymphocytes at age level; lymphocytes, monocytes and basophils for the white lineage at physiological stage level) were observed in animals suffering from C. abortus.En la República de Benín, el aborto es uno de los problemas reproductivos de las explotaciones de pequeños rumiantes, y Chlamydia abortus es uno de los agentes causales. El objetivo de este estudio era determinar por primera vez la prevalencia serológica y los parámetros hematológicos en pequeños rumiantes positivos a Chlamydia abortus en Benín, principalmente en el departamento de Ouémé. Abarcó cinco emplazamientos, a saber, Akpro-Missérété, Avrankou, Adjarra, Sèmè-Kpodji y Dangbo, en el departamento de Ouémé. Se analizaron 385 sueros (200 ovejas y 185 cabras) de sujetos que presentaban signos de pérdida reproductiva mediante el método Elisa indirecto. De los 385 sueros analizados, 30 (7,79%) resultaron positivos para Chlamydia abortus. Del mismo modo, se analizó la sangre de los animales con resultados positivos para determinar los parámetros hematológicos utilizando el analizador de sangre automatizado Sysmex XN-Series. Se observaron variaciones con diferencias significativas en algunos parámetros hematológicos de la línea roja y los de la línea blanca, en función de los lugares de estudio, la especie, la edad y el estadio fisiológico de los animales (hemoglobina, volumen corpuscular medio para la línea roja en los lugares, linfocitos y basófilos para la línea blanca en los lugares; hemoglobina para la línea roja y linfocitos para la línea blanca a nivel de especie; linfocitos a nivel de edad; linfocitos, monocitos y basófilos para la línea blanca a nivel de estadio fisiológico) se observaron en los animales afectados por C. abortus

Performance environnementale et economique dans la production de la grande morelle (Solanum macrocarpon) au Sud du Benin : Une evaluation des efficacites technique, allocative, economique

L’objectif de cette étude est d’analyser les efficacités technique, allocative et économique dans la production de la grande morelle. Pour cela, une  étude descriptive et analytique a été réalisée sur un échantillon de 126 maraîchers des sites de production de Houéyiho, de Sèmè-Kpodji et de  Ouidah au sud du Bénin. Les efficacités technique et économique ont été estimées respectivement à l’aide des modèles frontières stochastiques translogarithmique et fonction de coût dual avec la spécification Cobb-Douglas. Le modèle de régression tobit a été utilisé afin d’identifier les facteurs déterminants les efficacités des producteurs. Les résultats obtenus montrent que les facteurs main-d’oeuvre et engrais chimique sont sur-utilisés, ce qui entraîne des inefficacités dans la production. Les efficacités technique, allocative et économique sont respectivement en moyenne de 0,689 ; 0,882 et de 0,607. L’âge du producteur, la superficie emblavée, la contribution de la grande morelle dans le revenu, le niveau d’instruction et la formation technique sont les principaux déterminants des efficacités technique, allocative et économique des producteurs de la grande morelle. Sur la base des résultats obtenus, il importe d’améliorer l’efficacité des producteurs et augmenter ainsi leur profit par la recherche de moyens de lutte efficace et le renforcement de l’encadrement technique des producteurs. Mots clés : efficacités, frontières stochastiques, fonctions translog, fonction Cobb-Douglas, Solanum macrocarpon. English title: Environmental and economic performance in the production of the great nightshade (<i>Solanum Macrocarpon</i>) in southern Benin: An assessment of technical, allocative and economic efficiencies The objective of this study is to analyse the technical, allocative and economic efficiencies in the production of Solanum macrocarpon in Southern-Benin. For this purpose, a descriptive and analytical study was conducted among 126 Solanum macrocarpon growers in Cotonou, Sèmè-kpodji and Ouidah. The technical and economic efficiencies were estimated respectively using translogarithmic stochastic frontier models and dual cost function with the Cobb-Douglas specification. The Tobit regression model was used to identify the determinants of producers efficiencies. The results show that labor and chemical fertilizers are overused, leading to inefficiencies in production. The averages of technical, allocative and economic efficiencies are 0.689; 0.882 and 0.607 respectively. The age of the producer, the surface grown, the contribution of solanum in the income, the educational level and the training in farming are the principal determinants of the technical, allocative and economic efficiencies of the solanum’s producers. On the basis of result obtained, it is important to improve the efficiency of the producers and thus to increase their profit by the search for effective means of pest control and the reinforcement of producer’s technical framing. Key words: efficiency, stochastic frontier analysis, translog function, Cobb-Douglas function, Solanum macrocarpon

Loss of protection with insecticide-treated nets against pyrethroid-resistant Culex quinquefasciatus mosquitoes once nets become holed: an experimental hut study

ABSTRACT: BACKGROUND: An important advantage of pyrethroid-treated nets over untreated nets is that once nets become worn or holed a pyrethroid treatment will normally restore protection. The capacity of pyrethroids to kill or irritate any mosquito that comes into contact with the net and prevent penetration of holes or feeding through the sides are the main reasons why treated nets continue to provide protection despite their condition deteriorating over time. Pyrethroid resistance is a growing problem among Anopheline and Culicine mosquitoes in many parts of Africa. When mosquitoes become resistant the capacity of treated nets to provide protection might be diminished, particularly when holed. An experimental hut trial against pyrethroid-resistant Culex quinquefasciatus was therefore undertaken in southern Benin using a series of intact and holed nets, both untreated and treated, to assess any loss of protection as nets deteriorate with use and time. RESULTS: There was loss of protection when untreated nets became holed; the proportion of mosquitoes blood feeding increased from 36.2% when nets were intact to between 59.7% and 68.5% when nets were holed to differing extents. The proportion of mosquitoes blood feeding when treated nets were intact was 29.4% which increased to 43.6-57.4% when nets were holed. The greater the number of holes the greater the loss of protection regardless of whether nets were untreated or treated. Mosquito mortality in huts with untreated nets was 12.9-13.6%; treatment induced mortality was less than 12%. The exiting rate of mosquitoes into the verandas was higher in huts with intact nets. CONCLUSION: As nets deteriorate with use and become increasingly holed the capacity of pyrethroid treatments to restore protection is greatly diminished against resistant Culex quinquefasciatus mosquitoes

Cotton pest management practices and the selection of pyrethroid resistance in Anopheles gambiae population in Northern Benin

<p>Abstract</p> <p>Background</p> <p>Pyrethroid insecticides, carbamate and organophosphate are the classes of insecticides commonly used in agriculture for crop protection in Benin. Pyrethroids remain the only class of insecticides recommended by the WHO for impregnation of bed nets. Unfortunately, the high level of pyrethroid resistance in <it>Anopheles gambiae </it>s.l., threatens to undermine the success of pyrethroid treated nets. This study focuses on the investigation of agricultural practices in cotton growing areas, and their direct impact on larval populations of <it>An. gambiae </it>in surrounding breeding sites.</p> <p>Methods</p> <p>The protocol was based on the collection of agro-sociological data where farmers were subjected to semi-structured questionnaires based on the strategies used for crop protection. This was complemented by bioassay tests to assess the susceptibility of malaria vectors to various insecticides. Molecular analysis was performed to characterize the resistance genes and the molecular forms of <it>An. gambiae</it>. Insecticide residues in soil samples from breeding sites were investigated to determine major factors that can inhibit the normal growth of mosquito larvae by exposing susceptible and resistant laboratory strains.</p> <p>Results</p> <p>There is a common use by local farmers of mineral fertilizer NPK at 200 kg/ha and urea at 50 kg/hectare following insecticide treatments in both the Calendar Control Program (CCP) and the Targeted Intermittent Control Program (TICP). By contrast, no chemicals are involved in Biological Program (BP) where farmers use organic and natural fertilizers which include animal excreta.</p> <p>Susceptibility test results confirmed a high resistance to DDT. Mean mortality of <it>An. gambiae </it>collected from the farms practicing CCP, TICP and BP methods were 33%, 42% and 65% respectively. <it>An. gambiae </it>populations from areas using the CCP and TICP programs showed resistance to permethrin with mortality of 50% and 58% respectively. By contrast, bioassay test results of <it>An. gambiae </it>from BP areas gave a high level of susceptibility to permethrin with an average mortality of 94%.</p> <p>Molecular analysis identified <it>An. gambiae </it>s.s, and <it>An. arabiensis </it>with a high predominance of <it>An. gambiae s.s </it>(90%). The two molecular forms, M and S, were also determined with a high frequency of the S form (96%).</p> <p>The <it>Kdr </it>gene seemed the main target- site resistance mechanism detected in CCP, TICP, and BP areas at the rates ranging from 32 to 78%. The frequency of <it>ace-1R </it>gene was very low (< 0.1).</p> <p>The presence of inhibiting factors in soil samples under insecticide treatments were found and affected negatively in delaying the development of <it>An. gambiae </it>larval populations.</p> <p>Conclusions</p> <p>This research shows that <it>Kdr </it>has spread widely in <it>An. gambiae</it>, mainly in CCP and TICP areas where pyrethroids are extensively used. To reduce the negative impact of pesticides use in cotton crop protection, the application of BP-like programs, which do not appear to select for vector resistance would be useful. These results could serve as scientific evidence of the spread of resistance due to a massive agricultural use of insecticides and contribute to the management of pesticides usage on cotton crops hence reducing the selection pressure of insecticides on <it>An. gambiae </it>populations.</p