Evolution des infections naturelles sur les mangues, les avocats et les bananes en Côte d’Ivoire et principaux champignons responsables

Objectif: Les altérations fongiques constituent une des causes majeures des pertes post récolte des fruits frais en Côte d’Ivoire. L’objectif de cette étude était d’analyser les infections naturelles qui apparaissent sur les fruits dans les principales zones de production du pays, et d’identifier les principaux agents pathogènes responsables.Méthodologie et résultats: L’étude a consisté à la collecte, de manière aléatoire, des fruits dans les zones Centre, Sud, Est et Nord du pays, à la notation quotidienne des infections naturelles apparues sur les fruits, sur une durée de 6 à 9 jours et à l’isolement ainsi que l’identification des champignons qui leur sont associés. Les résultats ont montré une évolution du taux cumulé des infections naturelles de tous les fruits et la présence de 16 groupes morphologiques dont les plus dominants sont ceux à thalle gris (93,75%) au niveau de la mangue, ceux à thalle noir cotonneux (73,53%) pour l’avocat et ceux à thalle rose (81,25%) pour la banane. L’identification a montré une diversité de champignons pathogènes dont les principaux genres sont : Colletotrichum, Fusarium, Aspergillus, Phoma, Penicillium, Curvularia, Botryodiplodia et Rhizoctonia.Conclusion et application des résultats: Les fruits frais subissent après récolte l’impact des champignons pathogènes par les infections qu’ils causent. Ces infections augmentent au fur et mesure que les fruits murissent. Ces résultats constituent une bonne base pour le renforcement des stratégies de lutte. Toutefois, des études complémentaires, notamment pathogéniques et moléculaires des principaux champignons, sont nécessaires pour mieux les connaître et envisager, ainsi, des méthodes intégrées de lutte plus inclusives.Mots clés: Fruits, post-récoltes, infections, champignons pathogènesEnglish AbstractObjective: Fungal alterations are one of the major causes of post-harvest losses of fresh fruit in Côte d'Ivoire. The objective of this study was to analyze the natural infections that appear on fruits produced in the main production areas of the country, and to identify the main pathogens.Methodology and results: The study consisted of random fruit collection in the main growing areas, daily recording of natural infections on the fruit over a period of 6 to 9 days and isolation of the associated fungi. The results showed an evolution of the cumulative rate of natural infections of all fruits and the presence of 16 morphological fungal groups of which the most dominant are those with grey thallus (93.75%) in mango, those with cottony black thallus (73.53%) for avocado and those with pink thallus (81.25%) for banana. Identification showed a diversity of pathogenic fungi including the genera Colletotrichum, Fusarium, Aspergillus, Phoma, Penicillium, Curvularia, Botryodiplodia and Rhizoctonia.Conclusion and application of results: Fresh fruits quality are influenced by pathogenic fungi through the infections they cause after harvest. These results provide a good basis for control strategy enhancement. However, additional studies, including pathogenic and molecular components of the main fungi, are needed to better understand them and thus consider more inclusive integrated control methodsKeywords: Fruits, post-harvest, infections, pathogenic fung

Étude Phytochimique et activité antifongique d'extraits de quelques Euphorbiaceae médicinales utilisées chez les Baoulé du District de Yamoussoukro (Côte d'Ivoire)

An ethnobotanical survey was carried out in the District of Yamoussoukro (Central Côte d’Ivoire) in order to evaluate the biocontrol potential against fungal plant pathogens, of Euphorbiaceous plants used as medicines by the native population. Twelve (12) species were collected. The antifungal activity was assessed using the two-fold dilution method on PDA medium with ethanolic and aqueous extract derived from leaves of six plants. Results pointed out that only 70% ethanolic extracts from Alchornea cordifolia (EE13) possess fungicidal properties on both Fusarium sp. and Phytophthora sp. The antifungal activities are more effective with ethanolic extracts than aqueous extracts. With a minimal inhibitory concentration MIC = 25±0.0 mg/ml, a minimal concentration for 50% of inhibition IC50 = 10±0.05 mg/ml and a minimal fungicide concentration MFC = 200±0.0 mg/ml Fusarium sp. appears to be the most sensitive. Phytophthora sp. is less sensitive with a MIC = 50±0.0 mg/ml, an IC50 = 12±0.05 mg/ml and a MFC = 200±0.0 mg/ml. Phytochemical screening revealed the presence of seven major groups of compounds among which saponins and catechin are the most abundant in aqueous extracts. Polyphenols, flavonoids, polyterpenes and sterols as well as tannins are present in both alcoholic and aqueous extracts of Alchornea cordifolia. These compounds could justify its antifungal activity and traditional use

Foliar Application of Boron during Flowering Promotes Tolerance to Cocoa (Theobroma cacao L.) Swollen Shoot Viral Disease

Boron nutrition is known to reduce the effect of some viral and fungal diseases on plant fitness. This study investigated the potential of boron application to improve yield and tolerance of cacao trees naturally infected by virulent cocoa swollen shoot virus (CSSV) strains and determined the effective dose and time of application. Foliar sprays of a commercial product containing 20.5% of boron were performed either at the onset of flowering’s peak of the little milking (early in November) or four weeks later (early in December) with four doses of boron (0, 31.25, 41.67, and 83.27 g/ha) in a randomized complete block design with four replications. We found that boron application improved foliar density and induced production of pods of normal shape meanwhile reducing the appearance of this misshapenness due to CSSV. Boron also increased the number of emitted flowers, cherelles and pods subsequently. Moreover, weight and size of fresh cocoa beans per pod were positively correlated to boron dosage. Interestingly, foliar sprays performed early in November resulted in less flat cocoa beans. Finally, the optimal dose of boron that reduced the adverse effects of the most virulent form of cocoa swollen shoot viral disease is 41.67 g/ha

Caractérisation Morphométrique des Abeilles Mellifères Elevées dans le Centre de la Côte d’Ivoire

This paper focuses on the impact of tutoring as a preferred method for clinical supervision of nursing students. The study was conducted by relying upon two main actors of this method, namely: the tutor and the tutored. The development of this work was based on comprehensive and analyticalreadings of previous work to highlight the effects of the tutoring method on the quality of clinical supervision of students. This work allowed us to appreciate the positive side of the impact of this method. Moreover, the analysis made at the end of this work and the figures obtained have allowed us to conclude that a start of tutoring will have significant benefits, mainly, for the tutor: teaching experiences, motivation, and development of critical thinking. Also for the tutored, it includes: the success of the training, the relational support, the construction of the professional identity, and the valorization.The characterization of bees is an important step towards better management and sustainability of beekeeping systems. However, in Cote d'Ivoire, honeybees are still poorly studied to date. The objective of this investigation is to determine, by classical morphometry, the possible breeds and ecotypes of honeybees in central Cote d'Ivoire. Samples of 30 worker bees per hive were collected from 2 to 3 beehives in beekeeper apiaries sited in the localities of N'Guessankro, Soungassou, Kouassi-kouassikro, Lengbekouassikro of Yobouekro and the National Polytechnic Institute Felix Houphouet-Boigny of Yamoussoukro. A total of 18 morphometric parameters was measured using a binocular loupe and a microscope. Statistical analysis revealed a biogeographic variation within the honey bee colony of Côte d'Ivoire, making it possible to discriminate them in local populations

IN VITRO ASSESSMENT OF BIOPESTICIDE BACILLUS THURINGIENSIS VAR. KURSTAKI HD- 1 EFFECTIVENESS ON PHYTOPHTHORA PALMIVORA, AGENT OF COCOA BLACK POD ROT IN CÔTE D’IVOIRE

Phytophthora Palmivora is responsible for the cocoa black pod rot in Côte d'Ivoire, with production losses varying from 20 to 40% depending on the regions. Effectiveness of the environmentally friendly biopesticide Bacillus thuringiensis var. kurstaki HD-1 was evaluated in vitro on the pathogen. The medium pea supercooled has been incorporated with the bioproduct at different concentrations: C1 = 100%, C2 = 50%, C3 =25%, C4 = 12.5% and C5 = 6.25%. This medium into Petri dishes was inoculated either by spreading, with 0.1 mL of P. palmivora inoculum at103 zoospores /mL, or with a mycelial disc of P. palmivora calibrated at 6 mm diameter in the center of the box. The results showed that the germination of zoospores was inhibited at the rate of 100% in the presence of the concentrations C1 and C2. This rate was 74.82 ± 21.53%, 73.17 ± 20.88% and 59.12 ± 39.05%, respectively, for C3, C4 and C5. The efficacy of the bioproduct is revealed by a significant reduction of mycelia growth ranging between 57.77± 2.4 to 100% in the presence of the concentrations C5 to C1. The IC50 of germination was 3.36% of concentration and the IC90 was 43.22%; while those which inhibit 50% and 90% of mycelial growth were 5.67% and 77.94% respectively. The biopesticide Btk HD-1 has a proven fungistatic effect against P. palmivora. Its effectiveness increases with its concentration. So it can be a valuable component of an integrated cocoa black pod management

IN VITRO ASSESSMENT OF BIOPESTICIDE BACILLUS THURINGIENSIS VAR. KURSTAKI HD- 1 EFFECTIVENESS ON PHYTOPHTHORA PALMIVORA, AGENT OF COCOA BLACK POD ROT IN CÔTE D’IVOIRE

Phytophthora Palmivora is responsible for the cocoa black pod rot in Côte d'Ivoire, with production losses varying from 20 to 40% depending on the regions. Effectiveness of the environmentally friendly biopesticide Bacillus thuringiensis var. kurstaki HD-1 was evaluated in vitro on the pathogen. The medium pea supercooled has been incorporated with the bioproduct at different concentrations: C1 = 100%, C2 = 50%, C3 =25%, C4 = 12.5% and C5 = 6.25%. This medium into Petri dishes was inoculated either by spreading, with 0.1 mL of P. palmivora inoculum at103 zoospores /mL, or with a mycelial disc of P. palmivora calibrated at 6 mm diameter in the center of the box. The results showed that the germination of zoospores was inhibited at the rate of 100% in the presence of the concentrations C1 and C2. This rate was 74.82 ± 21.53%, 73.17 ± 20.88% and 59.12 ± 39.05%, respectively, for C3, C4 and C5. The efficacy of the bioproduct is revealed by a significant reduction of mycelia growth ranging between 57.77± 2.4 to 100% in the presence of the concentrations C5 to C1. The IC50 of germination was 3.36% of concentration and the IC90 was 43.22%; while those which inhibit 50% and 90% of mycelial growth were 5.67% and 77.94% respectively. The biopesticide Btk HD-1 has a proven fungistatic effect against P. palmivora. Its effectiveness increases with its concentration. So it can be a valuable component of an integrated cocoa black pod management

Utilisation du broyat de péricarpes des cabosses de cacao comme milieu de culture alternatif pour la production de Bacillus thuringiensis var. kurstaki HD-1

La recherche de matières premières alternatives pour la production de biopesticides microbiens suscite beaucoup d’intérêts. La présente étude s’est proposée d’utiliser le broyat de péricarpes des cabosses de cacao comme substrat de fermentation pour produire Bacillus thuringiensis var. kurstaki HD-1 (Btk HD-1). Les échantillons de péricarpes des cabosses ont été collectés dans une plantation cacaoyère de Toumokro à Yamoussoukro en Côte d’Ivoire. Les paramètres physico-chimiques ont été déterminés selon les méthodes standards. Le substrat de fermentation a été autoclavé, 2 fois successivement, à 121 °C pendant 30 min et ensemencé avec 4% de l’inoculum de Btk HD-1. Il ressort de cette étude que les teneurs en carbone et en azote total ont été respectivement de 79.7% et 1.4%. Les concentrations en minéraux du substrat ont été plus élevées en calcium (8406.5 mg/kg) et en potassium (8248.8 mg/kg) qu’en magnésium (632.6 mg/kg), sodium (471.5 mg/kg), fer (57 mg/kg), cuivre (52.8 mg/kg), zinc (51.8 mg/kg) et manganèse (44.3 mg/kg). Le dénombrement des cellules et des spores viables a donné respectivement 3.2.1011 et 3.02.1011 UFC/ml, pour le surnageant, et 6.5.1013 et 5.02.1013 UFC/ml, pour le culot. Ce substrat végétal offre une bonne perspective pour la production d’un biopesticide à base de Btk HD-1.© 2016 International Formulae Group. All rights reserved.Mots-clés: Péricarpes des cabosses de cacao, biopesticide, Bacillus thuringiensis var. kurstaki HD-1, fermentation en milieu solide, Côte d’IvoireEnglish Title:  Use of crushed cocoa hulls as an alternative culture medium for Bacillus thuringiensis var. kurstaki HD-1 productionEnglish AbstractResearch for alternative raw material for microbial biopesticides production raises outstanding interests.This study is proposed to use the crushed pericarps cocoa pods as fermentation substrate to produce Bacillus thuringiensis var. kurstaki HD-1 (Btk HD-1). The samples pericarps pods were collected in a cocoa plantation of Toumokro in Yamoussoukro area, Côte d'Ivoire. The physico-chemical parameters were determined using standard methods. The fermentation substrate was autoclaved 2 times successively at 121 °C for 30 minutes and inoculated with 4% of Btk HD-1 inoculum. It appears from this study that the carbon and total nitrogen were 79.7% and 1.4% respectively. Mineral concentrations in substrate were higher in calcium (8406.5 mg/kg) and potassium (8248.8 mg/kg) than magnesium (632.6 mg/kg), sodium (471.5 mg/kg), iron (57 mg/kg), copper (52.8 mg/kg), zinc (51.8 mg/kg) and manganese (44.3 mg/kg). Cell counts and viable spores gave respectively 3.2.1011 and 3.02.1011 CFU/ml, to the supernatant, and 6.5.1013 and 5.02.1013 CFU/ml, for the pellet. This vegetal substrate offers a good prospect for Btk HD-1 based biopesticide production.© 2016 International Formulae Group. All rights reserved.Keywords: Cocoa hulls pod, biopesticide, Bacillus thuringiensis var. kurstaki HD-1, solid medium fermentation, Côte d’Ivoir

Caracterisation D’isolats Locaux De Metarhizium Spp, Champignon Entomopathogene De Cosmopolites Sordidus Germar, Isoles Des Bananeraies En Cote d’Ivoire

Chemical insecticides have been commonly used against the black weevil, Cosmopolites sordidus, in banana plantations which caused huge economic and agricultural losses. Despite their benefits, pesticides can be hazardous to both humans and the environment. Intensive research in substituting chemical insecticides with biological control agents have been driven. The biological and molecular characteristics of ten strains of Metarhizium spp, isolated from dead weevils, collected in banana plantation in Côte d'Ivoire were studied. The study aims to identify the species of Metarhizium sp. The biological and molecular characteristics namely: length and width of the spores, colour of aerial mycelium as well as its variation over time, colour on the setback of the box, production of the diffusible pigment and the analysis of the region ITS (Internal Transcribed Spacer) were evaluated. The colonies presented at first a flat white mycelium cottony or fluffy appearance on which the spores formed small islets. After 21 days of incubation at 32°C. in the dark, the mycelium takes on the periphery a greenish coloration with a powdery appearance. The relief is fairly flat. The spores are ellipsoid in shape of 3 μm in length and 1 μm. The amplification by ITS-DNA PCR generated a specific fragment of 550 bp. The analysis of the ITS region of the sequences of these ten (10) isolates showed maximal correspondence with different strains of M. anisopliae and Metarhizium pinghaense

Widespread occurrence of copy number variants and fixation of pyrethroid target site resistance in Anopheles gambiae (s.l.) from southern Cote d’Ivoire

Resistance to pyrethroid and organophosphate insecticides in the malaria vector Anopheles gambiae (s.l.) is conferred by a variety of genetic mutations, including single nucleotide polymorphisms (SNPs) and copy number variants (CNVs). Knowledge of the distribution of these mutations in mosquito populations is a prerequisite for establishing better strategies for their management. In this study, a total of 755 Anopheles gambiae (s.l.) from southern Côte d’Ivoire were exposed to deltamethrin or pirimiphos-methyl insecticides and were screened to assess the distribution of SNPs and CNVs known or believed to confer resistance to one or other of the insecticide classes. Most individuals from the An. gambiae (s.l.) complex were identified by molecular tests as Anopheles coluzzii. Survival to deltamethrin (from 94% to 97%) was higher than to pirimiphos-methyl (from 10% to 49%). In An. gambiae (s.s.), the SNP in the Voltage Gated Sodium Channel (Vgsc) at the 995F locus (Vgsc-995F) was fixed, while other target site mutations were rare or absent (Vgsc-402L: 0%; Vgsc-1570Y: 0%, Acetylcholinesterase Acel-280S: 14%). In An. coluzzii, Vgsc-995F was the target site SNP found at highest frequency (65%) followed by other target site mutations (Vgsc-402L: 36%; Vgsc-1570Y: 0.33%; Acel-280S: 45%). The Vgsc-995S SNP was not present. The presence of the Ace1-280S SNP was found to be significantly linked to the presence of the Ace1-CNV, Ace1_AgDup. Significant association was found between the presence of the Ace1_AgDup and pirimiphos-methyl resistance in An. gambiae (s.s.) but not in An. coluzzii. The deletion Ace1_Del97 was found in one specimen of An. gambiae (s.s.). Four CNVs in the Cyp6aa/Cyp6p gene cluster, which contains genes of known importance for resistance, were detected in An. coluzzii, the most frequent being Dup 7 (42%) and Dup 14 (26%). While none of these individual CNV alleles were significantly associated with resistance, copy number in the Cyp6aa gene region in general was associated with increased resistance to deltamethrin. Elevated expression of Cyp6p3 was nearly associated with deltamethrin resistance, although there was no association of resistance with copy number. Use of alternative insecticides and control methods to arrest resistance spread in An. coluzzii populations is merited

Discrimination of bee populations in Côte d'Ivoire by geometrical morphometry | JBES 2022

A single honeybee subspecies, Apis mellifera adansonii, has been described from all of West and Central Africa. The data in the literature concerning the characteristics of honeybees present in Côte d’Ivoire are less numerous than in European subspecies. The present study characterizes the morphological diversity and deepens the knowledge of the local subspecies of honeybees thanks to a geometric morphometrics approach based on the configuration of the landmarks located on the wings, from a sample of 1,620 worker bees of the subspecies Apis mellifera adansonii collected in the Center, North and West of Côte d’Ivoire. Geometric morphometrics indicates that despite the diverse shapes and colors observed, the collected honeybees constitute a fairly homogeneous group with an absence of geographical differentiation within the colonies. Published by the Journal of Biodiversity and Environmental Sciences | JBE