Potentialit�S D&Apos;Utilisation Des Huiles Essentielles Des Plantes Locales Du Cameroun Pour Le Contr�Le Du Vers Rouge De La Farine Tribolium Castaneum (Herbst.) (Coleoptera : Tenebrionidae)

Animal feed is food constituted for breeding stock animals because it possesses vital nutrients for animal growth. Animal feed or their ingredients as constituted by cereal flour and are stored after formulation for ulterior breeds. These provender or cereal grains used are commonly attacked by storage insects principally of the genus Tribolium. Firstly, contact and ingestion test by two essential oils of aromatics plants Ocimum gratissimum L (Lamiaceae) and Xylopia aethiopica Dunal A. Rich (Annonaceae) were done firstly on adults and aged larvae of Tribolium castaneum . Secondly, the contact and inhalation test by three essential oils of the aromatic plants Annona senegalensis L. (Annonaceae), Lippia rugosa L. (Lamiaceae) and Hyptis spicigera Lam. (Verbenaceae) were done for the control larvae, young and aged adults of the red flour weevil Tribolium castaneum Herbst (Coleoptera : Tenebrionidae) very resistant pest to chemical pesticides. Essential oils of Ocimum gratissimum and Xylopia aethiopica have no contact and ingestion effect on adults of Tribolium castaneum ; their insecticidal activity is characterized mostly by their inhibition of the nymphosis of aged larvae of the same species. On the other hand contact and inhalation tests with crude essential oils of Lippia rugosa and Hyptis spicigera are the most promising because of their efficacy on the other life stages. They are more efficient, with 100% mortality, on larvae at early stages and young adults. On resistant aged larvae and adults, the insecticidal efficacy decreases but remains significant. Since this insect, Tribolium castaneum is the major pest of stored flours and provender, the incorporation of these promising essential oils in flours or in storage formulations of these foods for animals could contribute to their better cereal food conservation. The important and indispensable element of cereals for storage, growth and reproduction animal feed could be preserved from insects attack by use of natural product and may contribute to diminish toxicity of feeder, environmental pollution and the resistance phenomenon of insects.Les aliments pour animaux sont des aliments composés de plusieurs ingrédients pour élever des animaux parce qu'ils possèdent les éléments nutritifs vitaux pour l'animal. Les provendes ou leurs ingrédients constitués principalement par la farine des céréales; sont entreposés après formulation pour des utilisations ultérieures. Les provendes ou les grains de céréale utilisés sont attaqués au cours du stockage principalement par les insectes du genre Tribolium. Premièrement, la toxicité par contact et ou par ingestion de deux huiles essentielles de plantes aromatiques Ocimum gratissimum L (Lamiaceae) et Xylopia aethiopica fDunal A. Rich (Annonaceae) a été effectuée sur les larves âgées et les adultes de Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) ravageur principal de farine ou des provendes. Deuxièmement, la toxicité par contact et ou par inhalation de trois huiles essentielles des plantes Annona senegalensis L. (Annonaceae), Lippia rugosa L (Lamiaceae) et Hyptis spicigera Lam. (Verbenaceaea) a été effectuée pour le contrôle des différents stades larvaires, des jeunes et vieux adultes de Tribolium castaneum insecte résistant aux pesticides chimiques. Le test par contact et ou par ingestion effectué avec les huiles essentielles d'Ocimum gratissimum et Xylopia aethiopica n'ont montré aucun effet sur adultes de Tribolium castaneum ; leur activité insecticide est caractérisée principalement par l'inhibition de la nymphose des larves âgées. Le test par contact et ou par inhalation montre que les huiles essentielles brutes de Lippia rugosa et Hyptis spicigera sont les plus prometteuses à cause de leur efficacité sur les autres stades de développement ; elles sont plus efficaces sur larves les plus jeunes et les jeunes adultes avec 100% mortalité, pour les larves âgées résistants et les adultes, l'efficacité de l'effet insecticide diminue mais reste considérable. Vu que cet insecte; Tribolium castaneum est le ravageur principal de farines entreposées et des provendes, l'incorporation de ces huiles essentielles prometteuses dans les farines ou lors de la formulation de nourritures pour animaux pourrait contribuer à une meilleure conservation de ces dernières. Les éléments importants indispensables pour l'entretien, la croissance et la reproduction pour l'animal pourraient être conservés contre les attaques des insectes par les produits naturels et contribuer à réduire la toxicité du consommateur, la pollution environnementale et les phénomènes de résistance chez les insectes

Persistence Of Active Compounds Of Essential Oils Of Clausena Anisata (Rutaceae) And Plectranthus Glandulosus (Labiateae) Used As Insecticides On Maize Grains And Flour

Maize occupies an important place in the resolution of food insecurity problems in the sub-Saharan region of Africa. However due to poor post-harvest technologies, more than 35% of annual crop yield is often lost during storage as a consequence of insect attack. While chemical pesticides constitute an efficient tool for reducing these losses, current excessive usage runs the risk of modifying the quality and safety of foods produced from these grains. The use of essential oils of plant origin for grain storage has been advocated as a non invasive method with limited or no effect on the quality and safety of the grains or their products. This study was carried out as an evidence of bioactivity of two essential oils of Clausena anisata (Willd.) Hook and Plectranthus glandulosus Hook F. against adults of Tribolium castaneum Herbst and Sitophilus zeamais Motschulsky, which are two important stored product insect pests in Northern Cameroon. Because of the low persistence of the insecticidal activities of these plants, their essential oils to achieve a complete protection of the stored products must be applied at frequent delays. The present investigation focuses on the occurrence of residues of these oils on treated maize grain and flour. The doses of crude essential oils used to treat adults of S. zeamais and T. castaneum in a contact and inhalation process were their LD99s. After the evaluation of their insecticidal activity the persistence of each essential oil was observed every 2 days till 14 days. After the disappearance of their insecticidal activities, essential oil was re-extracted and their residual compounds were identified from treated grain and flour. The major compounds of C. anisata are, estragole, α-humulene, germacrene D and (E)-nerolidol. In P. glandulosus they are: fenchone, α-terpinolene and piperitenone oxide. After 14 days, only 64.24% of compounds of C. anisata were recovered on treated flour and 55.16% on grains. Concerning P. glandulosus, 48.94% was recovered on grains and 61.23% on flour

Is drinking water from 'improved sources' really safe? A case study in the Logone valley (Chad-Cameroon).

Within a cooperation project coordinated by the Association for Rural Cooperation in Africa and Latin America (ACRA) Foundation, water supplies were sampled across the villages of the Logone valley (Chad-Cameroon) mostly from boreholes, open wells, rivers and lakes as well as from some piped water. Microbiological analyses and sanitary inspections were carried out at each source. The microbiological quality was determined by analysis of indicators of faecal contamination, Escherichia coli, Enterococci and Salmonellae, using the membrane filtration method. Sanitary inspections were done using WHO query forms. The assessment confirmed that there are several parameters of health concern in the studied area; bacteria of faecal origins are the most significant. Furthermore, this study demonstrated that Joint Monitoring Programme (JMP) classification and E. coli measurement are not sufficient to state water safety. In fact, in the studied area, JMP defined ‘improved sources’ may provide unsafe water depending on their structure and sources without E. coli may have Enterococci and Salmonellae. Sanitary inspections also revealed high health risks for some boreholes. In other cases, sources with low sanitary risk and no E. coli were contaminated by Enterococci and Salmonellae. Better management and protection of the sources, hygiene improvement and domestic water treatment before consumption are possible solutions to reduce health risks in the Logone valley

Heavy metals in five leafy vegetables from urban and periurban sites in Ngaoundere, Cameroon

Heavy metal concentrations were estimated in five leafy vegetables (Solanum nigrum, Brassica oleraceae, Lactuca sativa, Amaranthus hybridus and Corchorus olitorius) from urban and periurban sites in Ngaoundere (Cameroon) using an Atomic Absorption Spectrophotometer (AAS). Vegetable samples were collected at the two stages of maturity: stage I (60 days) and stage II (90 days) for analysis. The results showed that the concentrations of heavy metals in all vegetables were greater in urban site than in periurban site. The highest concentrations of Fe (673.92 mg/kg DW), Cu (10.42 mg/kg), Cd (1.70 mg/kg DW), and Pb (31.75 mg/kg DW) were recorded in Lactuca sativa, Zn (94.60 mg/kg DW) in Solanum nigrum, and Ni (16.91 mg/kg DW) in Corchorus olitorius. The concentrations of Cu, and Pb were greater in roots than in aerial parts, while Fe, Cd, Ni and Zn concentrations were greater in aerial parts than in roots. Some of the concentrations of Ni, Zn and Pb in crops reached the critical level for plant growth. In general, the results indicated that the consumption of leafy vegetables harvested at the stage II potentially provides the greatest amount of heavy metals. The transportation index (Ti) decreased in vegetables harvested at the stage II for Fe, Cu, Cd and Zn but slightly increased for Ni and Pb, suggesting that heavy metal transportation from roots to aerial parts depends on the plant phenology and metal species. In all farms and at the two stages of maturity, the lead concentrations in all vegetables were more than the FAO/WHO maximum recommended level in leafy vegetable for human consumption. Moreover, all vegetables had some Cd concentrations that were higher than limits set by FAO/WHO. So, they are not suitable for human consumption

Physico-chemical properties of spring (Mineral) waters commonly consumed by grazing animals cattle in Wakwa (Cameroon)

Wakwa is an intensive cattle-grazing area in Northern Cameroon. The present study was carried out to determine the physico-chemical characteristics of different samples of spring waters commonly consumed by cattles in this area. Water samples were collected in dry season (February and April) of 2002 from four (Wakwa Palestine, Massagali, Djomtari and Lahoré Vina) springs and analysed for their mineral (NO3, Cl, PO43-, HCO3-, Ca, Mg, Mn, Al, Zn, Cu, Fe, ammoniacal nitrogen) and organic matter content using appropriate and current analytical methods (Absorption spectrophotometer, Inductive Coupled Plasma Atomic Emission spectrometry (ICP-AES) and Colorimetry). Mineral content of the waters was found to vary very significantly (p3-, Na, Ca, the Mg, Na and K. In general, the levels of Mn and organic matter (0.05 mg, l.4 mg of O2/l, respectively) found in the Lahoré Vina springs were higher than the E.P.A recommended levels. Equally high in these waters were the levels of such trace elements as Al and Mn. Zinc concentrations were highest in waters obtained from Wakwa Palestine Springs. Iron levels in the different waters did not vary with source. Based on an average daily consumption of 21 litres a day water from the Lahoré Vina springs grazing animals could meet their requirements of Na and Ca. On the same basis, the other sources can supply only about 14 and 5% of daily requirements for Na and Calcium

Physicochemical characteristics of lake IRAD, an artifical lake in Wakwa region, Cameroon

Wakwa is a region in north Cameroon characterized by intensive cattle production. This study evaluated the physicochemical characteristics of the waters in Lake IRAD, located near Wakwa, which is the main water source for cattle grazing in this area. Water samples were collected at four sampling sites during the rainy and dry seasons (April, July, October and February). The chemical composition of the water samples was analysed for various constituents, including nitrate (NO3–), chloride (Cl−), phosphate (PO43−), bicarbonate (HCO3−), calcium (Ca), magnesium (Mg), manganese (Mn), aluminium (Al), zinc (Zn), copper (Cu), iron (Fe), nickel (Ni), cadmium (Cd), ammonia–nitrogen (NH4–N) and organic matter (OM). The mineral composition varied significantly (P < 0.05) with the sampling period. High concentrations of zinc (0.96 mg L−1) and dissolved iron (1.23 mg L−l) were observed during the dry season. Total iron (3.25 mg L−1), OM (15.4 mg of O2 L−1), nitrate (28.82 mg L−1) and NH4–N (1.05 mg L−1) concentrations were highest during the rainy season. The iron, OM and NH4–N concentrations were higher than the USEPA-recommended values (0.2 mg L−1, 4 mg of O2 L−1 and 0.5 mg L−1, respectively). The phosphate, copper, nickel and cadmium concentrations, considered as the polluting substances, were present in negligible concentrations, being below the detection limits of the analytical techniques used to measure them. The high iron, OM and nitrogen concentrations were attributed to water-leached soil run-off, as well as the activity of animals in the lake. Sampling sites 1 and 2, which were used mostly by cattle, were observed to have the highest concentrations of NH4–N, compared with sites 3 and S (exit point). It will be necessary to delimit cattle access points to the lake to reduce this type of contamination of drinking water