Etude De L’efficacité Du Cashew Nut Shell Liquid (CNSL) De Anacardium Occidentale L. Extrait À Froid Sur Le Contrôle De Anopheles Gambiae S.L Résistant Aux Pyréthrinoïdes

In order to combat the vectors of malaria, it is necessary to know their behavior with regard to the insecticide products envisaged. The present study is aimed at the CNSL efficiency test extracted from the seed hull of Anacardium occidentale L. for the control of pyrethroid-resistant Anopheles gambiae s.l. Sensitivity tests were carried out on the larvae of stages 2, 3 and 4 of An. gambiae of the wild and Kis-kdr strains carrying the Kdr gene. The "Kisumu" strain devoid of resistance gene served as a control. The mortalities were read after 24 hours of exposure. LD50 and DL90 were determined using the log-probit method of dose determination corresponding to a proportion. The high LD50 determined is 0.0042 mg / ml and corresponds to the LD50 of the larvae of stage 2 of the wild strain. The low LD50 is determined on stage 2 larvae "Kisumu". The high DL90 is determined on stage 4 larvae of the wild strain. The low LD90 determined corresponds to stage 2 larvae "Kisumu". The comparison of the LD between the different strains shows a low sensitivity to CNSL of the larvae of resistant strains compared to the control strain, indicating the influence of the resistance factor kdr on the CNSL efficiency. However, the low-dose CNSL larvicidal activity on the larvae of the kdr-carrying strains provides an alternative advantage in the management of vector resistance to pyrethroid

Efficacy of two plant powders as cowpea grain protectants against Callosobruchus maculatus Fabricius (Coleoptera, Chrysomelideae: Bruchinae)

Objective: This study was carried out to study insecticidal effect of powders from Chenopodium ambrosioides leaves and Aframomum melegueta seeds on cowpea weevil Callosobruchus maculatus.Methodology and Results: 5g of both powders of A. melegueta and C. ambrosioides were used in the proportions of C. ambrosioides 100%:A. melegueta 0%, C. ambrosioides 0%: A. melegueta 100%, C. ambrosioides 30%: A. melegueta 70%, C. ambrosioides 70%: A. melegueta 30% and C. ambrosioides 50%: A. melegueta 50%. Plant powders were added to 20g of cowpea grains. Bioassays were conducted at 26.64±0.74°C and 72.55±4.38% relative humidity. Insect mortality was evaluated from 24 to 144 hours after treatment. Results obtained indicated that plant powders had significant effect on C. maculatus mortality. The highest mortality rate (70.00±26.45%) was recorded in jar treated with C. ambrosioides.Conclusion and application of findings: Either plant powders, alone or mixed had high insecticidal effect on C. maculatus. Because of their effectiveness, these plant powders could be recommended as grain protectants against C. maculatus.Key words: Chenopodium ambrosioides, Aframomum melegueta, Callosobruchus maculatus, Insecticidal activit

Identification and Larvicidal Efficacy of Mosquito-Repelling Plants Used in Malaria Vector Control in South-East Benin

After identifying issues posed by some synthetic insecticides, the scientific community is now looking for other natural products with insecticidal and/or insect repellent characteristics. This study aimed to identify the plants of the Beninese flora known for their insecticidal and/or insect repellent effects and the indigenous techniques of their use and to evaluate the combined efficacy of extracts of a few on mosquito larvae for the control of malaria vectors in the South-East of Benin. A survey was conducted and the insecticidal effects of three combinations made from Azadirachta indica, Cymbopogon nardus and Hyptis suaveolens oils on Anopheles gambiae larvae were studied. The data were analyzed using R software, and Chi-square test was used to compare death rates. Twelve (12) plant species were identified. The combinations of C. nardus and H. suaveolens oils induced the highest mortality rates (90 ± 4.15% and 68 ± 9.14% with stages 2 and 3 larvae, respectively). The application of extracts from these plants to control the malaria vectors population would reduce the use of chemical pesticides, hence the need to promote and enhance the formulations of biopesticides based on plant extracts. Keywords:    Plant species, biopesticides, mosquito-repelling plants, vectors. &nbsp

Etude De L’efficacité De L’huile De Thevetia Neriifolia Pour Le Contrôle De Anopheles Gambiae S.L Résistant Aux Pyréthrinoïdes

Effective control of pyrethroid-resistant malaria vectors requires new alternative measures. The purpose of this study is to test the effectiveness of Thevetia oil extracted from seed kernels to control malaria transmission by An. gambiae s.l. Sensitivity tests were carried out on larvae of Stages 3 and 4 of An. gambiae s.s of wild-type and pyrethroid-resistant Kis-kdr. The susceptible reference strain "Kisumu" served as a control. Mortality was read 24 hours and 48 hours after exposure. LD50 and 90 for 24 hours and 48 hours were determined using the log-probit method of determining the dose corresponding to a proportion. The high LD50s determined in 24 hours and 48 hours correspond to doses that kill 50% of Stage 3 larvae in wild populations in 24 hours and 48 hours. Low LD50s refer to stage 4 "Kisumu" larvae. The strong DL90 in 24 hours and 48 hours correspond respectively to stage 3 larvae of the Kis-kdr and wild-type strains. The comparison of the LD between the different strains shows the influence of the resistance on the sensitivity of the larvae of the strains resistant to the oil tested. However, the larvicidal effect of Thevetia oil on the larvae of resistant strains may elicit formulations for alternative measures in vector resistance management to pyrethroids

Efficacy of mixed powders of Piper guineense and Zingiber officinale as maize grain protectants against Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae)

This study was carried out to evaluate the effects of mixed powders of Piper guineense (Piperaceae) and Zingiber officinale (Zingiberaceae) on Sitophilus zeamais population and seed weight loss percentage of stored maize. Experiment was conducted under laboratory conditions (26.94 ± 0.81 °C, 74.76 ± 4.51% r.h. and 12 h photoperiod). In a completely randomized design with three replications, powders of P. guineense and Z. officinale were applied separately and in mixtures at the ratios of Zg100%:Pg0% (T1), Zg0%:Pg100% (T2), Zg30%:Pg70% (T3), Zg70%:Pg30% (T4) and Zg50%:Pg50% (T5), respectively. The mortality rate of S. zeamais adults was recorded and compared with the control at 24, 48, 72, 96, 120 and 168 hours after treatment. Maize grain damage and seed weight loss percentage were determined. Results showed highly significant differences with S. zeamais mortality rate between treatments, treatment exposure duration and their interactions (p<0.001). P. guineense, alone, showed the best efficacy (mortality rate = 96.66 ± 5.77% at 96 hours after treatment) and mixed with Z. officinale at the ratio 70%Pg: 30Zo (mortality rate = 93.33 ± 5.77%). Taking into account this high performance of P. guineense seed powder, it can be recommended as stored maize grain protectants.Keywords: Botanical insecticides, maize storage, Sitophilus zeamais, weight loss, mortality rate

Potato production in Benin – Its impact on fighting hunger and poverty in West Africa

Kartoffeln ergeben pro Flächeneinheit mehr Kalorien als jede andere Nutzpflanze. Sie enthalten wichtige Nährstoffe und bieten der Bevölkerung in ländlichen Anbaugebieten eine Einkommensquelle. Benin ist eines der ärmsten Länder der Welt. Eine Maßnahme, der Armut entgegenzuwirken, wird in der Ausdehnung der Kar­toffelanbaufläche gesehen. Voraussetzung dafür ist, u.a. Klarheit über die Produktionsstruktur in Benin zu erhalten, sowie die Produktionsbedingungen einzuschätzen und in diesem Zusammenhang, Aussagen zur phyto­pathologischen Situation zu treffen. Die Kartoffelanbaugebiete befinden sich in den De­partements Alibori und Atakora im Norden Benins. Die Anbaufläche liegt insgesamt bei ca. 15–20 ha. Eine Ausdehnung auf eine Anbaufläche im vierstelligen Hektar­bereich erscheint denkbar. In diesem Fall ist jedoch eine nationale Pflanzgutproduktion notwendig. Kartoffeln werden, da Bewässerung notwendig ist, traditionell auf einer nahe den Flüssen oder Nebenarmen gelegenen Fläche von 0,25 ha pro Familie angebaut. Das Pflanzgut gelangt größtenteils aus Frankreich oder aus einem der kartoffelproduzierenden Nachbarländer nach Benin. Der Kartoffelertrag liegt bei ca. 15 t/ha. Maßnahmen, den Ertrag zu erhöhen, liegen in der Verbesserung des Bewässerungssystems und der Pflanzengesundheit. Im Ergebnis von Untersuchungen zum Gesundheits­status der in Benin produzierten Kartoffelknollen wurde festgestellt, dass die Kartoffeln einem hohen Befallsdruck durch Ralstonia solanacearum, einem Quarantäneschaderreger im EPPO Raum, ausgesetzt waren und einen moderaten Befall mit Kartoffelviren aufwiesen. In zukünftige Untersuchungen sollten die Nassfäule­erreger R. solanacearum aber auch der Pectobacterium spp. -Komplex verstärkt einbezogen werden.    Potatoes produce more calories per area than any other agricultural crop. The tubers are rich in substances valuable for human nutrition. Furthermore, farmers can sell potatoes on the market thus providing a stable income for their family. Benin is one of the poorest countries in the world. One option to minimize hunger and poverty is to increase potato production. Potatoes are grown in the regions of Alibori and Atakora in the north of Benin covering a total area of 15 to 20 ha. To increase this area to thousands of hectares a national seed potato production is required. Potato production, traditionally the task of the farmers’ family takes place on fields with an area of approx. 0.25 ha close to small rivers because of water supply for irrigation. Seed potatoes are imported from France or potato producing neighbouring countries. The potato yield amounts to about 15 t/ha. To increase the potato yield, the irrigation system has to be improved and pests have to be controlled. Potatoes produced in Benin were analyzed for pathogens. The performed preliminary monitoring for selected quarantine pests as indicated by EPPO showed that bacterial infection with R. solanacearum was present in one region. All tested crops were found to be free of the selected quarantine viruses and viroid. The investigated plant material was moderately infected by common potato viruses that are not listed in the quarantine lists of EPPO. Further research is needed to estimate the role of the irrigation system as potential source for bacterial infections such as R. solanacearum or the Pectobacterium spp. complex.   &nbsp

Enquêtes Ethnobotaniques et Caractérisation des Pratiques Endogènes de Gestion des Ravageurs sur Quelques Sites Maraîchers au Sud-Bénin

L’une des contraintes liées à la production maraîchère, est la pression exercée par les insectes ravageurs. Ce travail a consisté en une enquêtes ethnobotaniques et caractérisation des pratiques endogènes de gestion des ravageurs sur quelques sites maraîchers au sud-Bénin, dans le cadre de la formulation des pesticides botaniques pour la gestion des principaux ravageurs de cultures maraîchères. Cette étude est basée sur les caractéristiques socioéconomiques des enquêtés, l’état de connaissances du producteur sur les cultures maraîchères, les contraintes et méthodes de lutte des cultures, et les méthodes d’utilisation de la plante. Un questionnaire d’enquête portant sur l’étude ethnobotanique des plantes et la caractérisation des pratiques endogènes de gestion des nuisible a été élaborée et adressé auprès 240 maraîchers sur une période de trois mois (de mai 2018 à Juillet 2018) pour la collecte des données. Ces données ont été soumises à une analyse descriptive et une analyse en composante principale. L’étude a révélé que 12 espèces de légumes sont cultivées par les maraîchers de la zone d’étude à cause de leur cycle assez court et leur préférence par les consommateurs. Ces légumes sont dominés par la grande morelle, le chou, la tomate et la carotte en termes de proportion. Le recours aux pesticides de synthèse non homologués pour le contrôle des ravageurs reste la méthode de lutte la plus utilisée. Les connaissances ethnobotaniques collectées sur quatre plantes à savoir : le neem, le moringa, le papayer et le tabac, au cours de nos enquêtes sont très riches mais détenues par très peu de personnes, majoritairement âgées d’au moins 50 ans (88,98%). Ces plantes se répartissent en quatre familles (Caricaceae, Moringaceae, Méliacées, Solanacées) dont les Méliacées sont les plus utilisées. Les parties des plantes les plus utilisées sont les feuilles et les graines. Cette collection de plantes indiquées par les maraîchers dans la lutte contre les ravageurs des cultures maraîchères peut constituer une base des données pour des tests biologiques et des analyses phytochimiques. One of the constraints related to vegetable production is the insect pests pressure. This work consisted of ethnobotanical surveys and characterization of endogenous pest management practices in a few gardening sites in southern Benin, as part of the formulation of botanical pesticides for the management of major gardening pests. This study is based on the socioeconomic characteristics of the surveyeds, the state of knowledge of the producer on gardening, constraints and methods of the crop control, and methods of the plant use. A survey quiz on the ethnobotanical study of plants and the characterization of endogenous pest management practices was developed and sent to 240 market gardeners over a period of three months (May 2018 to July 2018) for data collection. These data were subjected to a descriptive analysis and a principal component analysis. The study revealed that 12 species of vegetables are grown by market gardeners in the study area because of their rather short cycle and their preference by consumers. These vegetables are dominated by large nightshade, cabbage, tomato and carrot in terms of proportion. The use of unregistered synthetic pesticides for pest control remains the most widely used control method. The ethnobotanical knowledge collected on four plants namely: neem, moringa, papaya and tobacco, during our surveys are very rich but held by very few people, mostly aged at least 50 years (88,98 %). These plants are divided into four families (Caricaceae, Moringaceae, Meliaceae, Solanaceae) whose Meliaceae are the most used. The most used plant parts are leaves and seeds. This collection of plants indicated by market gardeners in the fight against vegetable crop pests can constitute a database for biological tests and phytochemical analyzes

Evaluation Au Laboratoire De L’effet Larvicide Du Baume De Cajou Et De Trois Huiles Végétales À Base Des Plantes De Tephrosia Purpurea, Ricinus Communis Et Thevetia Neriifolia Pour Contrôler Les Populations De Plutella Xylostella L. 1758 (Lepidoptere, Pl

Cette étude a évalué l’effet larvicide du baume de cajou extrait à froid et de trois huiles végétales à base des plantes de Tephrosia purpurea, Ricinus communis et Thevetia neriifolia, dans les conditions d’élevage au laboratoire de Plutella xylostella L. 1758 (Lepidoptera, Plutellidae) insecte ravageur du chou au Bénin. L’efficacité des biopesticides étudiés a été comparée à celle d’un insecticide de synthèse (Lambda cyalothrine) et à celle d’un pesticide botanique de référence (Topbio). Des tests ont été réalisés sur les larves des stades 2 et 3 de P. xylostella. Deux expérimentations ont été réalisées dans cette étude. Dans la première expérimentation, les produits ont été testés sur le stade L3 de P. xylostella, avec les doses de 100%, 75%, 50%, 25% et 10% de chacun des produits végétaux et de Lambda Cyhalothrine. A la deuxième expérimentation, les mêmes produits végétaux ont été testées sur le stade L2 du même insecte avec les doses de 50%, 25%, 10%, 5%, 3%, 2% et 1% comparées au témoin de référence Lambda cyalothrine aux doses de 10%, 5%, 3%, 2%,1%, 0,5%. Les mortalités ont été observées toutes les 24 heures jusqu’au neuvième jour après exposition. Le dispositif utilisé pour les tests biologiques est un bloc complètement randomisé. La formule d’Abbott a été utilisée pour corriger les taux de mortalité au niveau des insectes traités. Les variables mesurées sont la mortalité des larves, la formation des chrysalides et l’émergence des adultes. Ces variables sont soumises à une analyse de variance avec le logiciel XLSTAT version 2019. Les DL 50 pour cinq jours ont été déterminées suivant le modèle de regression de Cox de détermination de la dose correspondante à une proportion. Les résultats ont montré que les huiles végétales et le baume de cajou sont les biopesticides prometteurs pour le contrôle des populations de P. xylostella. Pour la première expérimentation, les taux de mortalité des larves L3 de P. xylostella n’étaient pas significativement différents entre les doses d’application de 25% de Topbio et d’huile de T. purpurea. Des mortalités de 100% ont été enregistrées avec les doses de 100%, 75%, 50% et 25% de tous les produits utilisés sur le stade L2 et L3. Lors de la deuxième expérimentation, 100% de mortalité ont été enregistrées à une dose d’application de 10% respectivement pour le Topbio, l’huile de T. purpurea, le CNSL, et l’huile de R. communis. Aucune différence significative n’a été enregistrée au seuil de 5% entre les doses de 10% d’huile de T. purpurea et 3% du témoin de référence Lambda cyalothrine. Les témoins ont enregistré le plus fort taux de chrysalides et d’adultes. Ces deux paramètres ont été fonction de la dose. Pour tous les produits utilisés, quel que soit le stade larvaire de P. xylostella, la réponse effet/dose a été significative. Le baume de cajou et les trois huiles végétales se positionnent comme une alternative aux pesticides de synthèses pouvant être utilisé en culture maraîchère.   This study aims to evaluate the larvicidal effect of three vegetable oils: Tephrosia purpurea, Ricinus communis, Thevetia neriifolia, and cashew balm in the management of Plutella xylostella L. 1758 (Lepidoptere, plutellidae) pest insects of cabbage in the laboratory. The efficacy of the extracts has been compared to that of a synthetic insecticide (Lambda cyalothrin) and that of a botanical pesticide (Topbio). Larval tests were carried out on larvae of stages 2 and 3. Two experiments were set up in this study. In the first experiment, the products were tested on the L3 stage of P. xylostella, with the doses of 100%, 75%, 50%, 25% and 10% while in the second, the same products were tested on the L2 stage of the same insect with the doses of 50%, 25%, 10%, 5%, 3%, 2% and 1% compared to the reference control Lambda cyalothrin at the doses of 10%, 5%, 3 %, 2%, 1%, 0.5%. The mortalities were read 24 hours after exposure until the ninth day. The device used for biological tests is a completely randomized block. Abbott's formula has been used to correct mortality rates for treated insects. The variables measured are the mortality rate, the formation of pupae and the emergence of adults. These variables are subjected to an analysis of variance with the XLSTAT software version 2019. The LD 50 for eight days were determined according to the Cox regression method of determining the dose corresponding to a proportion. The results showed that vegetable oils and cashew balm are the promising species in the management of dose-dependent P. xylostella. For the first experiment, the mortality rates of L3 larvae of P. xylostella were not significantly different between the 25% application doses of Topbio and T. purpurea. Mortalities ranging from 100% were recorded with the doses of 100%, 75%, 50% and 25% of all the products used on the L2 and L3 stages. During the second experiment, 100% mortality was recorded at an application dose of 10% respectively for Topbio, T. purpurea, CNSL, and R. communis. No significant difference was recorded at the 5% threshold between the 10% doses of T. purpurea and 3% of the reference control Lambda cyalothrin. Witnesses recorded the highest rate of pupae and adults. These two parameters were a function of the dose. For all the products used, whatever the larval stage of P. xylostella, the effect / dose response was significant. Cashew balm and the three vegetable oils are positioned as an alternative to synthetic pesticides that can be used in market gardening

Efficacite Du Baume De Cajou Contre Les Chenilles Carpophages Du Cotonnier Au Nord Du Benin

Cotton remains the main source of foreign exchange for Benin. This study aims to contribute to increased yield of organic cotton through the evaluation of the effectiveness of cashew balm as an alternative method of management of carpophagous pests of cotton. The experimental setup consists of Fisher Blocks with 6 objects in 4 repetitions. The objects compared are '' Unprocessed '', the Agri-bio-pesticide dosed at 1 l / ha, two concentrations (1% and 2%) of the hot and cold-extracted cashew balm. Linear mixed or fixed effects models and generalized linear models with mixed or fixed effects were used to determine the influence of the objects on the carpophagous larva and their damage in 2015 and 2016 in Thya to the north of Benin. The number of Helicoverpa armigera larva found in 30 plants ranged from 1.2 (Agri-biopesticide) to 2.3 (Untreated) in 2015. The percentages of green capsules with holes varied by 36.08% (Agri-bio-pesticide) at 53.68% (1% cold-extracted balm) in 2015. The percentages of ripe capsules with holes varied from 32.05% (hot-pressed balm at 2%) to 45.00% (Untreated) in 2016. Seed cotton yield ranged from 229.91 kg / ha (Untreated) to 500 kg / ha (Agri-biopesticide) in 2016. It is noted that Agri-bio-pesticide and the 2% dose of cashew balm, were more effective than that of 1%. The cashew balm is positioned as an alternative to biopesticides used in organic cotton farming