Toxicity of two plant powders as biopesticides in the management of Callosobruchus maculatus F. (Coleoptera: Chrysomelidae, Bruchinae) on two stored grain legumes

Objective: The present study aimed to evaluate effects of leaf powder of Chenopodium ambrosioides (wormseed) and Adenia cissampeloides (snake climber) on insect populations and seeds weight loss percentage.Methodology and Results: Two leaf powders were applied at 2.5%, 5% and 7.5% (wt/wt). All bioassays were conducted at 27±2°C and 70±5%RH. Insect mortality was evaluated after 2, 4 and 6 days of exposure and thetotal progeny was assessed 34 days after. C. ambrosioides at 2.5% showed the best efficacy, recording 69.64% of mortality in Vigna  subterranea groundnuts and 100% of mortality in Kerstingiella geocarpa one’s, 6 days after treatment. The lowest LC50 value after 6 days was obtained with A. cissampeloides applied at 2.37g/20g of V. subterranea groundnuts and with C. ambrosioides applied at 1.38 g/20g of K. geocarpagroundnuts.Conclusion and application of findings: Because of their effectiveness, the leaf powder of these plants could be recommended as grain protectant against C. maculatus.Key words: Botanical insecticides, pulses weevil, grain legumes, plant extracts, mortality rate

First report of outbreaks of the fall armyworm Spodoptera Frugiperda (J E Smith) (Lepidoptera, Noctuidae), a new alien invasive pest in West and Central Africa

Article purchasedThe fall armyworm Spodoptera frugiperda is a prime noctuid pest of maize on the American continents where it has remained confined despite occasional interceptions by European quarantine services in recent years. The pest has currently become a new invasive species in West and Central Africa where outbreaks were recorded for the first time in early 2016. The presence of at least two distinct haplotypes within samples collected on maize in Nigeria and São Tome suggests multiple introductions into the African continent. Implications of this new threat to the maize crop in tropical Africa are briefly discussed

Effet protecteur des feuilles de Opilia celtidifolia contre l’ulcère induit par l’éthanol chez le rat

Opilia celtidifolia est une plante traditionnellement utilisée contre les plaies et l’ulcère gastro duodénal. Le but de ce travail était d’étudier l’activité antiulcéreuse des extraits aqueux de cette de la plante. Des extraits aqueux, total et épuisé, ont été préparés par décoction. Le décoté total a été testé à 100 et 200 mg/kg et le décocté épuisé à100 mg/kg. Le Sucralfate a été utilisé comme témoin positif à la dose de 1000 mg/kg et le groupe non traité a reçu de l’eau distillée à10 ml/kg. Les extraits ont été administrés par voie intragastrique, une heure après, 0,5 ml d’éthanol à 90% a été administré aux animaux pour provoquer l’ulcère pendant une heure. Après ce temps, les rats ont été sacrifiés. L’estomac de chaque rat a été ouvert pour observer et compter les ulcères. L’indice d’ulcère a été exprimé et le pourcentage de protection a été calculé. A 100mg/kg, le décocté épuisé a induit une protection de la muqueuse de 75%, contre 31% pour le décocté total. Le Sucralfate, utilisé comme témoin a présenté une protection de 87,50%. Ces résultats démontrent que les feuilles de Opilia celtidifolia peuvent intervenir dans le traitement de l’ulcère gastrique. La mise au point d’un phytomédicament contre l’ulcère gastrique à base des feuilles de cette plante est donc envisageable.Mots clés : Opilia celtidifolia, protection, ulcère gastrique

Review on Phytochemistry and Pharmacological Aspects of Guiera Senegalensis J. F. Gmel (Combretaceae)

Medicinal plants are the local heritage with global importance. They have curative properties due to presence of various complex chemical substances of different composition, which are found as secondary plant metabolites in one or more parts of these plants. These plant metabolites according to their composition are grouped as flavonoids, tannins, alkaloids, saponins etc...Guiera SenegalensisnbspJ. F. Gmel. (Combretaceae) is one of the most important West African medicinal plants, often used to treat a variety of microbial infections.nbs

Savoir traditionnel sur les plantes antipaludiques à propriétés analgésiques, utilisées dans le district de Bamako (Mali)

Objectif : Le but de cette étude était de recenser les plantes utilisées dans la prise en charge traditionnelle de la douleur palustre.Méthodologie et résultats : Les enquêtes ont été menées de février à mars 2011 dans le district de Bamako et le cercle de Kati. Les informations ont été collectées par une nouvelle méthode d’enquête ethnobotanique dénommée «Achat en Triplet de Recettes Médicinales (ATRM)» couplée à l’interview semi-structurée auprès de vingt quatre tradipraticiens de santé (herboristes et tradipraticiens de santé composés de dix sept femmes (70,8%) et sept hommes (29,2%). Au total 54 espèces médicinales appartenant à 52 genres de 21 familles ont été recensées. Les Fabaceae (ex-Caesalpiniaceae), les Rubiaceae, les Combretaceae et les Asteraceae sont les familles les plus représentées. Onze espèces ont été recensées par les deux méthodes à la fois. Mitragyna inermis et Anogeissus leiocarpus étaient les plus citées. Les recettes de la présente étude sont principalement préparées par décoction (92,8%) et majoritairement administrées par voie orale (52,6%). Les espèces recensées provenaient principalement des savanes, foret, champs de culture et de jachère. Mitragyna inermis (Willd.) O. Kuntze, Afrormosia laxiflora (Benth. ex Bak.) Harms, Parkia biglobosa (Jacq.) Benth, Pteleopsis suberosa Engl. & Diels, Cassytha filiformis Linn., Tamarindus indica Linn., sont véritablement menacées dans leur biotope à cause de leur surexploitation en médecine traditionnelle et méritent d’être sauvegardées pour leur conservation aux générations futures.Conclusion et application des résultats : La présente étude montre que les herboristes et tradipraticiens de santé de Bamako connaissent des plantes analgésiques utilisées dans la prise en charge traditionnelle du paludisme. Cette étude a aussi montré que certaines espèces sont menacées. Des investigations ultérieures sont nécessaires pour sélectionner certaines espèces identifiées puis vérifier in vivo leurs activités analgésiques.Mots clés : Ethnobotanique, plantes antipaludiques, propriétés analgésiques, nouvelle méthode, Mali

A novel sustainable platform for scaled manufacturing of double‑stranded RNA biopesticides

Open Access Journal; Published online: 06 Oct 2022RNA interference (RNAi) represents one of the most conserved pathways evolved by eukaryotic cells for regulating gene expression. RNAi utilises non-translatable double-stranded RNA (dsRNA) molecules to sequester or degrade mRNA molecules gene. In RNAi, specifically designed exogenous dsRNA delivered to the cell can silence a target gene, a phenomenon that has been exploited in many functional studies and explored in biopesticide applications. The search for safe and sustainable crop pest management options drives the need to offset the effect of inorganic pesticides on biodiversity. The prospect of replacing inorganic pesticides with dsRNA crop spray is gaining popularity, enhanced by its high-target specificity and low environmental impact. However, for dsRNA to reach the pesticide market, it must be produced cost-effectively and sustainably. In this paper, we develop a high-yield expression media that generates up to 15-fold dsRNA yield compared to existing expression media utilising 1 mM IPTG. We also optimise a low-cost purification method that generates high-quality and purified dsRNA. The developed method circumvents the need for hazardous chemical reagents often found in commercial kits or commercial nucleases to eliminate contaminating DNA or single-stranded RNA (ssRNA) species. We also demonstrate that the production platform is scalable, generating 6.29 mg dsRNA from 259 mg wet E. coli cell pellet. The results also provide structural insights into the heterogeneous dsRNA species within the microbial-derived dsRNA pool. Finally, we also show that the purified ‘naked’ dsRNA, without prior formulation, can induce insect toxicity under field conditions. This study provides a novel, complete, low-cost process dsRNA platform with potential for application in industrial dsRNA production

A genome-wide scan divulges key Loci involved in resistance to aphids (Aphis craccivora) in cowpea (Vigna unguiculata)

Open Access Journal; Published online: 01 Nov 2022Cowpea aphids (Aphis craccivora Koch) double as a direct damaging pest and a virus vector to cowpea, threatening the economic yield of the crop. Given the multiple ecotypes, different alleles have been implicated in aphid resistance, necessitating the identification of key genes involved. The present study implemented a genome-wide scan using 365 cowpea mini-core accessions to decipher loci involved in resistance to aphid ecotype from Kano, Nigeria. Accessions were artificially inoculated with A. craccivora in insect-proof cages and damage severity assessed at 21 days after infestation. Significant phenotypic differences based on aphid damage severity were registered among the accessions. Skewed phenotypic distributions were depicted in the population, suggesting the involvement of major genes in the control of resistance. A genome-wide scan identified three major regions on chromosomes Vu10, Vu08 and Vu02, and two minor ones on chromosomes Vu01 and Vu06, that were significantly associated with aphid resistance. These regions harbored several genes, out of which, five viz Vigun01g233100.1, Vigun02g088900.1, Vigun06g224900.1, Vigun08g030200.1 and Vigun10g031100.1 were the most proximal to the peak single nucleotide polymorphisms (SNPs) positions. These genes are expressed under stress signaling, mechanical wounding and insect feeding. The uncovered loci contribute towards establishing a marker-assisted breeding platform and building durable resistance against aphids in cowpea

Potential of sorghum and physic nut (Jatropha curcas) for management of plant bugs (Hemiptera: Miridae) and cotton bollworm (Helicoverpa armigera) on cotton in an assisted trap-cropping strategy

The cotton bollworm (CBW) Helicoverpa armigera and to a lesser extent plant bugs (PB) (Hemiptera: Miridae) are important pests of cotton in Africa. For sustainability reasons, it is necessary to reduce use of chemical control measures for these pests. A promising alternative to chemical control of both CBW and PB is trap cropping, assisted with botanical pesticides sprays, if needed. We report studies conducted from 1995–98 on sorghum attractiveness to PB and CBW, on the potential of physic nut (Jatropha curcas) extracts [particularly the phorbol ester (PE) fraction of the oil] for sorghum protection fromPB damage, and on the insecticidal activity of Jatropha extracts on CBW. At the ICRISAT research station (Samanko, Mali), infestation by the five main species of PB (accounting for 96% of total) was much higher on sorghum than on cotton. In the Kolokani region, CBW infestation was negligible on the Guinea loose-panicled sorghum cultivar Bibalawili, while it was significant on both compact-panicled PB susceptible ICSH 89002 and PB resistant Malisor 84-7. At Samanko, Jatropha oil application on sorghum panicles showed some effect on PB when damage level was high, better than Jatropha and neem aqueous extracts. However, it did not compete with pyrethroid protection level. PE contact toxicity on CBW larvae was too low to determine a LC 50. Aningestion insecticidal activity of PE was found on all tested larval instars. Contact toxicity LC 50 of PE on eggs was 1.66 g ml-1. Development of larvae and reproductive ability of adults derived from new-laid eggs treated with solutions of 0.35 g ml-1 PE and above were considerably affected. Prospects for using sorghum and Jatropha extracts for cotton protection against insect pests in an assisted trap-cropping strategy are discussed