Bugs (Heteroptera), secondary devastators in comparison to caterpillars before 1980, constitute nowadays an important entomologic factor in the shedding of buds and new bolls.An evaluation of their damage and that of the caterpillars on shed organs was realized in an apparatus corresponding to a three method of protection.Statistical analyses (ANOVA) of results have shown in the first mode (NT) that the average of bugs' damage on buds (49.25 ± 3.94) and new bolls (101.5 ± 6.65) is significantly higher than that of caterpillars (36.75 ± 3.25) and (51.75 ± 7.43) respectively.Treatments realized in the second mode (ST) allowed the reduction of the average of bugs' damage by 31.50 ± 5.12 on buds and by 61.25 ± 2.75 on new bolls and that of caterpillars by 24.25 ± 2.62 and by 29.00 ± 4.43 respectively on buds and on bolls.The treatment of the third mode (PP) also led to a reduction of bugs' damage by 24.25 ± 2.65 on buds and by 56.25 ± 7.20 on new bolls and respectively 16.25 ± 1.93 and 29.75 ± 3.06 the damage of caterpillars.
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.
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.
The recognition of the loss of sensitivity of insect pests to several synthetic active ingredients is putting crop phytosanitary protection programs in difficulty.In order to exploit the different modes of action of the active compounds of natural pesticides for an effective and lasting control of pests, the aphicidal effect of extemporaneous mixtures of the essential oil of Ocimum canum and that of Ocimum basilicum L., two plants of the Togolese flora, was evaluated in vitro on Aphis gossypii.The tests were carried out in the laboratory according to the IRAC N° 1 Version 2 methodology.The results obtained showed that the essential oil of O. canum potentiates the action of the essential oil of O. basilicum, using small amounts of O. canum mixed with high amounts of O. basilicum.The inhibition ratios (IR) confirmed these results In vitro evaluation …
With the aim of contributing to the fight against phytopathogens, an evaluation of the antifungal activity of the aqueous extracts of the seeds of Azadirachta indica on the development of Sclerotium rolfsii, a pathogenic fungus of the rhizomes of Zingiber officinale , was carried out through bioassays on mycelial growth and sclerotia formation. The biological tests were carried out in vitro by systemic application on S. rolfsii . The results obtained revealed a sensitivity of the fungus S. rolfsiidifferent concentrations of seed extracts and the commercial fungicide product Mancozeb. The concentration of 50 gl-1 of the extracts and of Mancozeb induced high inhibition rates which are respectively 76.37±7.35% and 80.14±3.4% on the mycelial growth of S. rolfsii . The numbers of sclerotia formed were reduced in the dishes at concentrations of 50 gl-1 (4.1±1.1 of sclerotia) and 20 gl-1 (7±1.8 of sclerotia) of the extracts. The 50 gl-1 concentration of the plant extract was more effective in inhibiting mycelial growth and sclerotia formation of S. rolfsii . The results of this study suggest that the aqueous extract from the seeds of A. indica can be used preventively in S. rolfsii control strategies .
The impacts of agricultural production on the environment are becoming increasingly intense and diversified.In order to contribute to the reduction of risks related to the use of pesticides, this work was carried out in Togo in the Northern Plateaux Region.The study was carried out, in cotton-based farming systems, among producers in the cantons of Kolocopé, Gbadjahé and Elavagnon, through surveys and direct observations in the fields.The results revealed that producers in these cantons use plant protection products intensively.Management and protective measures during and after the use of these products are still insufficient, and practices that pose health risks have been observed.Crop rotation and crop rotation systems in these localities promote natural soil fertilization.However, certain practices, such as the combination of food crops with cotton, expose humans to pesticides through trophic routes.These observations show that efforts are still needed to reduce this exposure.Furthermore, the determination of pesticide residues in food products from this area of cotton-based cropping system will allow the level of exposure to be assessed as accurately as possible.
It is worth controlling arthropods, cotton plant devastators for a production in quantity and quality. Phytophagous bugs, secondary devastators before 1980 in Togo constitute nowadays an important entomological factor with regard to their density and damage they cause. Their inventory was conducted through young plant felling and threshing in 4 agro-ecological regions. This process shows that these insects connected to floral and fruit-bearing phase are abundant and diversified. 55 species belonging to 7 families have been counted. The family of Pentatomidae is the most represented in species. In contrary, the family of Miridae is the most abundant followed respectively by Pyrrhocoridae and Pentatomidae. The four (4) agro-ecological regions are similar in terms of bugs’ diversity. These results can be useful in the improvement of fighting strategies.
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