This study aims at appraising the capability of tannic powders of African locust been pod husks (Parkia Biglobosa) and of the India tamarind (Pithecellobium dulce) peel to bind Africa antiaris sawdust particles in order to manufacture environmental panels without formaldehyde emission. In the process, the granulometry has been studied. Thus, four granular groups (g) are obtained: 1.6 < g ≤ 5; 0.8 < g ≤ 1.6; g ≤ 0.8; and the raw sawdust (non-sieved). The panels produced from the different powders have been characterized. The mechanical characteristics (MOE: modulus of elasticity and MOR: modulus of rupture) determined by the bending tests are found to respect the threshold specified by the ANSI A208.1 (Medium density fiberboard, National Particleboard Association, Gaithersburg, 2009) standard. The thermal conductivity values of the panels allow concluding that the manufactured panels are conventional insulators according to the French standards RT 2012. The analyses have shown that the panels are of Mean Density in conformity with ANSI A208.1 (Medium density fiberboard, National Particleboard Association, Gaithersburg, 2009) standard.
L’usage massif des pesticides chimiques en protection phytosanitaire présente un danger énorme sur la santé publique et sur l’environnement. Il s’impose de trouver des moyens de protection écologique respectueux de l’environnement. Dans cette étude, l’activité insecticide de l’huile essentielle d’Eucalyptus globulus a été évaluée au laboratoire et en milieu réel contre deux ravageurs importants du cotonnier, Pectinophora gossypiella et Thaumatotibia leucotreta. Les larves de ces ravageurs ont été exposées d’abord à l’effet toxique des différentes concentrations de l’huile essentielle par test de contact et par ingestion au laboratoire. Les taux de mortalité enregistrés ont été comparés aux témoins absolus et de référence. Les résultats ont montré que l’huile essentielle d’E. globulus a exercé une activité insecticide importante sur les larves. En effet, l’huile essentielle a entrainé un taux de mortalité de 100 et 99% à la dose 1µl/ml respectivement sur P. gossypiella et T. leucotreta après 24 heures d’exposition au test de contact. Avec le test d’ingestion, les taux de mortalité ont été 36 et 30,78% respectivement sur P. gossypiella et T. leucotreta. En milieu réel, les résultats des traitements à base des formulations d’huile essentielle d’E. globulus en comparaison avec l’insecticide de référence ont montré que les infestations des populations de P. gossypiella et T. leucotreta ont été plus faibles dans les modalités de traitement à base d’huile essentielle de E. globulus à 1µl/ml (TE3). L’analyse sanitaire des capsules vertes a montré une réduction du nombre de ravageurs de 6,25±1,29 T. leucotreta par plant dans les parcelles témoins absolus à 3,29±0,52 dans les parcelles à traitement TE3. Il a été observé également une réduction du nombre de 9,04±1,38 P. gossypiella par plant (témoin absolu) à 4,13±0,39 (TE3). Les rendements moyens élevés en coton graine ont été de 1933,10±0,29Kg et 1927,08±0,12Kg/ha respectivement avec le témoin référence TV et TE3. Il a été faible dans les parcelles témoins absolus avec 1197,92±0,33Kg/ha. L’extrait d’E. globulus possède une activité insecticide potentielle au laboratoire comme au champ.
The massive use of chemical pesticides in plant protection poses an enormous threat to public health and the environment. We need to find ecological protection methods that respect the environment. In this study, the insecticidal activity of Eucalyptus globulus essential oil was evaluated in the laboratory and in the field against two major cotton pests, Pectinophora gossypiella and Thaumatotibia leucotreta. The larvae of these pests were first exposed to the toxic effect of different concentrations of the essential oil by contact test and by ingestion in the laboratory. The mortality rates recorded were compared with absolute and reference controls. The results showed that the essential oil of E. globulus exerted significant insecticidal activity on the larvae. Indeed, the essential oil caused a mortality rate of 100 and 99% at the dose of 1µl/ml respectively on P. gossypiella and T. leucotreta after 24 hours of exposure to the contact test. With the ingestion test, the mortality rates were 36 and 30.78% respectively on P. gossypiella and T. leucotreta. In the real environment, the results of treatments based on formulations of essential oil of E. globulus in comparison with the reference insecticide showed that infestations of P. gossypiella and T. leucotreta populations were lower in treatment modalities based on essential oil of E. globulus at 1µl/ml (TE3). Health analysis of the green bolls showed a reduction in the number of pests from 6.25±1.29 T. leucotreta per plant in the absolute control plots to 3.29±0.52 in the TE3 treatment plots. There was also a reduction in the number of P. gossypiella from 9.04±1.38 per plant (absolute control) to 4.13±0.39 (TE3). High average yields of seed cotton were 1933.10±0.29Kg and 1927.08±0.12Kg/ha respectively with the TV and TE3 reference controls. It was low in the absolute control plots with 1197.92±0.33Kg/ha. E. globulus extract has potential insecticidal activity both in the laboratory and in the field.
Sahlbergella singularis is one of the insects that causes the most damage to cocoa trees in Togo. The management of this pest is mainly based on chemical control, with its negative consequences for human health and the environment. In order to find an alternative to the use of synthetic pesticides, the insecticidal and repellent activities of neem oil were tested in vitro on fifth instar larvae and adults of S. singularis. Larvae were collected from a cocoa plot. The fifth instar larvae were separated from the other stages. Some of the larvae were reared in the laboratory until adult emergence. The concentrations of neem oil used were 0.5, 1, 1.5, 2 and 2.5 µl.ml-1. Insecticidal tests were carried out by spraying the solutions directly onto the insects. The repellency test was carried out using the preferential zone method on filter paper. The results showed an increasing mortality rate with increasing concentrations of neem oil for both fifth instar larvae and adults. The calculated LC50’s for larvae and adults were 0.89 and 0.98 µl.ml-1 respectively. Neem oil had a weak repellent effect on both fifth instar larvae and adults, with average repellency rates of 23.60% and 28.8% respectively. These results show that neem oil can be an alternative to the use of synthetic pesticides in the control of S. singularis.
Dans la perspective de contribuer à l’élaboration d’une stratégie de gestion intégrée du puceron de cotonnier Aphis gossypii, les tests de l’effet de la fumure minérale et des prédateurs sur la variation des niveaux de population de ce dernier ont été étudiés. La collecte des données a été réalisée par un suivi à chaque trois jour sur plants de cotonnier (Gossypium hirsutum L.) installé en parcelles expérimentales à la Station d’ Expérimentation Agronomique de l’Université de Lomé. Les résultats de la fluctuation de population d’Aphis gossypii ont révélé deux pics de pullulation durant le cycle du cotonnier. Le premier pic de la petite période de pullulation au 46ème jour après semis (jas) est moins important numériquement. Le second pic de la grande période de pullulation au 86ème jas est numériquement plus important et cause des dégâts considérables aux cotonniers. Les infestations et les niveaux de variation de populations au cours du cycle de la culture cotonnière sont très dépendants de la dose de fumure minérale appliquée La présence et le développement des prédateurs ont corrélé positivement avec le niveau d’infestation des plants par le puceron sans avoir un effet régulateur remarquable de la population de ce dernier.
Abstract The buds essential oil of Syzygium aromaticum (Myrtaceae) from Togo were steam-distilled and investigated for percentage composition and antimicrobial activity. Eugenol (82.95 %), eugenyl acetate (5.01 %), β-caryophyllène (3.14 %) were the major components of the analysed sample. The in vitro microbiological experiments revealed that on tested bacteria, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) ranged from 30 to 50 μl/L and from 60 to 120 μl/L respectively. This makes S. aromaticum suitable for use as a source of active ingredients in the formulation of natural toothpaste and lotions for mouth washes.
Currently, the fight against red bugs, a pest of the cotton plant, is limited to the use of synthetic chemical insecticides. Many of the products used are persistent and their high toxicity to human health and the environment is of concern. In the search for alternatives to synthetic chemical insecticides, the aim of this research work was to evaluate the insecticidal potential of aqueous emulsions based on the essential oil of Cymbopogon schoenanthus(L.) against Dysdercus voelkeri, one of the redoubtable pests of cotton plant in Togo. Aqueous emulsions at different concentrations were used in phytosanitary treatments on cotton crop compared to vulgarized binary insecticides (lambdacyhalothrin/profenofos 15/300 gha-1and cypermethrin/acetamiprid 36/8 gha-1). D. voelkeri counts on target plants of each elementary plot revealed that the highest dose of the emulsion (6%) of C. schoenanthus essential oil and the control (vulgarized insecticide)were more effective with low bug population densities of 7.14± 1.46 and 4.86± 1.84 bugs/plant,respectively. On the contrary,the other doses (4 and 2%) of emulsions based on C. schoenanthus essential oil had in their plots respectively 39.57 ± 5.81 and 45.28 ± 3.92 bugs/plant and the control (55.71± 5.23 bugs/plant). Health analysis of the young cotton bolls that fell under the cotton plants revealed that the highest dose of the emulsion (6%) and the control reduced stings by 71.40 and 72.33 % respectively, compared to the control. Stings reduction rates in plots with treatments of 4 and 2% of the emulsion were low with rates of 55.32and22.83%,respectively. These results clearly show that the aqueous emulsion formulated and tested in the study can significantly reduce attacks of these pests. This study shows the possibility of using the essential oil of C. schoenanthus as a raw material in the formulation of biopesticide as an alternative to synthetic chemical insecticides in the control of cotton plant red bugs in Togo.
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