Dynamique Saisonnière de Nedotepa curta (Homoptera, Cicadellidae) et Proutista fritillaris (Homoptera, Derbidae), Potentiels Vecteurs du Phytoplasme de la Maladie du Jaunissement Mortel du Cocotier de Grand-Lahou (Côte d’Ivoire)

En Côte d’Ivoire, le cocotier (Cocos nucifera L.) est essentiellement cultivé sur le littoral ivoirien et constitue la principale culture de rente en assurant des revenus à plus de 20 000 familles. Cependant, la plante est sujette à plusieurs contraintes dont la plus inquiétante actuellement est le jaunissement mortel du cocotier de Grand-Lahou. Ce travail vise à étudier la dynamique saisonnière des potentiels vecteurs du phytoplasme de la maladie du jaunissement mortel du cocotier à Grand-Lahou (Nedotepa curta et Proutista fritillaris). Les insectes ont été collectés avec des pièges à glu, hissés à l’aide d’une corde dans la couronne des cocotiers de deux villages de Grand-Lahou (Badadon et Yaokro), d’octobre 2015 à septembre 2016. Sur ces deux sites, les fluctuations les plus importantes des populations de N. curta et P. fritillaris ont été observées en décembre 2015 et en février 2016. L’analyse de corrélation de Pearson réalisée entre quelques facteurs abiotiques et les fluctuations des populations de ces insectes montre que la température et les fluctuations de ces insectes ne sont pas significativement corrélées. Par contre, il existe une influence hautement significative et négative (r˃-0,7 ; p˂0,0001) de la pluviométrie sur les populations de ces insectes. Une influence significative et négative (r˃-0,7 ; p˂0,005) de l’humidité relative sur ces insectes a été également observée. Les potentiels vecteurs du jaunissement mortel du cocotier de Grand-Lahou pullulent donc au cours des périodes sèches de l’année. La température n’affecte pas le développement de ces insectes alors que la pluviométrie et l’humidité relative diminue leur développement.   In Côte d’Ivoire, the coconut tree (Cocos nucifera L.) is cultivated essentially on the coastline of Côte d'Ivoire. It is one of the main cash crops that provide income to close to 20,000 families. The plant is subject to several constraints of which the most troubling one among them is the coconut lethal yellowing of Grand-Lahou. This paper focuses on the seasonal dynamics of the potentials vectors of phytoplasma of the coconut lethal yellowing of Grand-Lahou (Nedotepa curta and Proutista fritillaris). The insects were collected with traps tights, hoisted with the help of a rope in the crown of the coconut trees of two villages of Grand-Lahou (Badadon and Yaokro), from October 2015 to September 2016. On these two sites, the most important fluctuations of the populations of N. curta and P. fritillaris were observed in December 2015 and in February 2016. The realized Pearson interrelationship analysis between some abiotic factors and the fluctuations of the populations of these insects show that the temperature and the fluctuations of these insects are not correlated meaningfully. On the other hand, there is a highly meaningful and negative influence (r˃-0,7 ; p˂0,0001) of rainfall on the populations of these insects. A meaningful and negative influence (r˃-0,7 ; p˂0,005) of the relative humidity on these insects were also observed. The potentials vectors of the coconut lethal yellowing of Grand-Lahou swarm can be seen during the dry periods of the year. Although the temperature does not affect the development of these insects, the rainfall and the relative humidity decrease their development.&nbsp

Efficacité De La Pollinisation Entomophile Du Palmier A Huile Dans Les Plantations Du Sud-Ouest Et Du Sud-Est De La Côte d’Ivoire

Low fruit set rates in oil palm plantations may be related to inadequate entomophilous pollination. The objective of this study was to follow the variations of fruit set and to determine its relationships with the entomofauna visiting inflorescences at La Mé, Grand-Béréby and Iboké in Côte d’Ivoire. Densities of the insects were followed out on male and female inflorescences during 12 months. The fruit set rate was also monitored over the same period on young bunches. The results showed that pollination is provided by Elaeidobius kamerunicus, Elaeidobius plagiatus, Elaeidobius singularis, Elaeidobius subvittatus, Microporum congolense, Microporum dispar and Atheta burgeoni. At La Mé, the fruit set rate was negatively correlated with the damage of Prosœustus spp (r = -0.43, p = 0.01) and positively with the abundance of E. kamerunicus and E. plagiatus on female flowers (respectively: r = 0.60, p = 0.002 and r = 0.47, p = 0.020). At Grand-Béréby, it is negatively correlated with the damage of Prosœustus spp (r = -0.42, p = 0.01). At Iboké, positive correlations were observed with the density of E. subvittatus (r = 0.40, p ˂ 0.001), M. congolense (r = 0.41, p = 0.046), M. dispar (r = 0.57, p = 0.004) and A. burgeoni (r = 0.65, p ˂ 0.001). This study highlighted the necessity to manage the populations of pollinators and the inflorescences pest insects to improve the production of oil palm in Côte d'Ivoire

Malaria knowledge and long-lasting insecticidal net use in rural communities of central Côte d'Ivoire

ABSTRACT: BACKGROUND: To improve effectiveness of malaria control interventions, it is essential to deepen the knowledge of contextual factors that govern people's practice for preventive and curative measures. The aim of this study was to determine factors that influence the use of long-lasting insecticidal nets (LLINs) in three rural communities of Cote d'Ivoire, two of which benefited from recent interventions. METHODS: The study was carried out in 957 households in three villages (Bozi, N'Dakonankro and Yoho) located in central Cote d'Ivoire. Indicators of socioeconomic position (SEP), malaria knowledge and practice, placing special emphasis on LLINs, were investigated during a cross-sectional questionnaire survey. Principal component analysis was used to calculate the SEP of households by means of a list of household assets ownership. The concentration index was used to assess the direction of the association between SEP and a given variable. To compare groups or means, Fisher's exact test, chi2 and Kruskal-Wallis test were used, as appropriate. RESULTS: Significant differences were found between SEP and reported malaria symptoms, such as fever or hot body, convulsion, anaemia and jaundice (yellow eyes). Individuals from the least poor group cited more often the use of bed nets and insecticide-treated nets (ITNs) compared to poorer groups. The mean number of individuals reporting the use of bed nets and LLINs was different between groups with different educational level. Moreover, the mean number of LLINs in a household was influenced by the presence of children below five years of age. CONCLUSION: The study not only confirmed that education and SEP play important roles in the prevention and control of malaria and promotion of health in general, but pointed at the basic essential knowledge and the key behavioural elements that should guide education and learning processes among the poorer segments of the population. In turn, such knowledge may change behaviour and lead to an increased utilization of LLIN

Comparaison du potentiel insecticide des huiles essentielles de Ocimum gratissimum L. et de Ocimum canum Sims sur Pectinophora gossypiella Saunders (Lepidoptera : Gelechiidae), insecte ravageur du cotonnier en Côte d’Ivoire

The abusive use of synthetic pesticides in the phytosanitary protection of cotton in Côte d'Ivoire threatens the viability of the production system. The search for alternative control methods is therefore necessary. Phytosanitary strategies involving plant-based biopesticides have been explored. The insecticidal activity of essential oils of plant species of the genus Ocimum has been the subject of numerous investigations. The objective of this study is to compare the insecticidal potential of two species of the same genus Ocimum gratissimum and O. canum on a major cotton pest, the pink worm Pectinophora gossypiella. Adults of the insect were exposed in the laboratory to the toxic effect of different concentrations of these oils by topical application using a micro applicator. The lethal concentrations causing respectively 50 % (LC50) and 90% (LC90) death in the populations tested were determined for each of the essential oils. The oil extracted from O. gratissimum was the most toxic with LC50 and LC90 respective values of 1.01 % and 5.05 % as compared to O. canum (LC50 = 11.33 % and LC90= 30.04 %). The high toxicity of O. gratissimum may be explained by the presence of 24.57 % thymol and 37.79 % p-cimene in its chemical composition. The extract of O. gratissimum has shown in laboratory the highest potentiel insecticidal activity, it‘s field use can therefore be suggested for the control of this cotton pest

Sensibilité aux Insecticides des Populations de Bemisia tabaci (Gennadius, 1889) Collectées dans Différentes Zones de Production Cotonnière en Côte d’Ivoire

Ces dernières années, il a été constaté en Côte d’Ivoire une pullulation des populations de Bemisia tabaci en culture cotonnière malgré les traitements insecticides effectués. Une évaluation des niveaux de sensibilité aux insecticides couramment utilisés pour la protection des cotonniers a été entreprise en vue d’identifier les matières actives les plus efficaces contre B. tabaci. Des populations de mouches blanches ont été collectées dans six (6) différentes localités de la zone de production cotonnière (Niakara, Bouaké, Ouangolo, Ferké, Boundiali et Korhogo). Elles ont été testées par la méthode de trempage des rondelles de feuilles vis-à-vis de cinq (5) insecticides de familles chimiques différentes (Organophosphorés, Pyréthrinoïdes, Néonicotinoïdes, Sulfoximines, Spinosynes). Les CL50 pour chaque insecticide ont été calculées grâce au modèle probit-log et comparées à l’aide d’analyses univariées de variance (ANOVA). Les données ont montré une variabilité géographique de la sensibilité aux insecticides des populations de B. tabaci et une différence significative entre les niveaux de sensibilité de l’insecte vis-à-vis des insecticides testés. Les souches provenant de Korhogo ont présenté la plus faible sensibilité au profenofos (CL50=71,51 mg.l-1), et celles de Boundiali la plus faible sensibilité à l’acétamipride (CL50=219,96 mg.l-1).L’acétamipride s’est montré significativement moins toxique comparativement à la lambdacyhalothrine et au profenofos (F= 2,58 ; P=0,04). Le sulfoxaflor (CL50 moyenne=0,71 mg.l-1) et le spinosad (CL50 moyenne= 4,02 mg.l-1) ont été les produits les plus toxiques. Cette étude qui est la première du genre en Côte d’Ivoire représente une base de données pour la gestion des populations de B. tabaci. In recent years, an outbreak of Bemisia tabaci has been observed in Côte d'Ivoire in cotton crops despite the insecticide treatments. An evaluation of the sensitivity levels of insecticides commonly used for the protection of cotton trees has been undertaken in order to identify the most effective active ingredients against B. tabaci. Whitefly populations were collected in six (6) different localities in the cotton production area (Niakara, Bouaké, Ouangolo, Ferké, Boundiali and Korhogo). They were tested by the leaf dipping method with five (5) insecticides of different chemical families (Organophosphorus, Pyrethroids, Neonicotinoids, Sulfoximines, Spinosynes). LC50s for each insecticide were calculated using the probit-log model and compared using univariate analyses of variance (ANOVA). The data showed a geographical variability in insecticide susceptibility of B. tabaci populations and a significant difference between the levels of insect susceptibility to the insecticides tested. Strains from Korhogo showed the lowest susceptibility to profenofos (LC50=71.51 mg.l-1), and strains from Boundiali the lowest susceptibility to acetamiprid (LC50=219.96 mg.l-1). Acétamipride was significantly less toxic compared to lambdacyhalothrin and profenofos (F=2.58; P=0.04). Sulfoxaflor (LC50=0.71 mg.l-1) and spinosad (LC50=4.02 mg.l-1) were the most toxic products. This study, which is the first of its kind in Côte d'Ivoire, represents a database for the management of B. tabaci populations. &nbsp

Caractéristiques de l’évolution spatio-temporelle de Pectinophora gossypiella Saunders (Lepidoptera : Gelechiidae) dans les zones de production cotonnière de Côte d’Ivoire : Implications pour une stratégie de gestion optimale de la résistance aux pyréthrinoïdes

In order to update knowledge on the spatio-temporal evolution of Pectinophora gossypiella, the geographical areas and the seasons of predilection of adult and larval populations have been studied in the last six years from 2012 to 2017. The study showed that adult populations are more abundant in the cotton production area of the South compared to the North. They have a very low activity during the intercropping season while the most important outbreaks occurred in October-December. The monitoring of larval populations carried out on farm scale showed that infestations started on cotton early August and increased until November, which leads to a strong relationship between the evolution of adult populations, larval infestations and cotton plant phenology. Late sowings D5 and D6 exhibited higher levels of infestation (0.50 to 0.80 larvae/100 bolls) as compared to early sowing (0.21-0.31 larvae/100 bolls). Annual variations of pest infestation levels increased from years to years, fluctuating from 0.14 to 0.95 larvae/100 bolls over the study period. Mapping of the geographic distribution of infestation showed more severe pest pressure in the southern cotton areas, mostly in surrounding areas of Bouaké, Bouaflé, Séguéla and Boron (18,90; 5,33; 1,52; 1,06 larvae/100 bolls respectively). With regard to the emerging status of P. gossypiella over recent years, the current pyrethroid resistance management strategy deserves to be improved on the basis of the pest geographic and seasonal profiles

Caractéristiques de l’évolution spatio-temporelle de Thaumatotibia leucotreta Meyrick (Lepidoptera : Tortricidae) dans les zones de production cotonnière de Côte d’Ivoire

In order to update knowledge on the spatio-temporal evolution of Thaumatotibia leucotreta, the geographical areas and seasons of predilection of adult and larval populations have been studied in the last six years from 2012 to 2017. Monitoring of natural adult populations revealed that populations were more abundant in the southern cotton production area as compared to the north. A Monitoring of larval infestations showed that infestations occurred on cotton at the end of august (0.10 larvae/100 bolls) and increased gradually during october-november (0.31 to 0.93 larvae/100 bolls), indicating a strong relationship between evolution of adult and larval populations and cotton phenology. Early sowings exhibited higher infestation levels (0.87 larvae/100 bolls). Annual variations of pest infestation levels increased from years to years, from 0.23 to 0.49 larvae/100 bolls over the study period. Mapping the geographic distribution of infestations showed highest pest densities in the southern zone, mostly in surrounding areas of Boron (1.52 larvae/100 bolls). With regard to the emerging status of T. leucotreta over recent years, the current pyrethroid resistance management strategy deserves to be improved on the basis of the pest geographic and seasonal profiles