PERSISTENCE OF ACTIVE COMPOUNDS OF ESSENTIAL OILS OF CLAUSENA ANISATA (RUTACEAE) AND PLECTRANTHUS GLANDULOSUS (LABIATEAE) USED AS INSECTICIDES ON MAIZE GRAINS AND FLOUR

ABSTRACT 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 LD 99 s. 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

Antioxidant activities of essential oils of Clausena anisata (Rutaceae) and Plectranthus glandulosus (Labiateae), plants used against stored grain insects in North Cameroon

This study was carried out to evaluate the overall antioxidant capacity of the essential oils of the leaves of Clausena anisata (Rutaceae) and Plectranthus glandulosus (Labiateae), commonly used in the traditionalmethod of grain storage in the northern part of Cameroon. Towards this objective, the co-oxidation of β-carotene as well as the reducing power, the radical scavenging capacity and the conjugated dienes profile of theessential oils during storage for a period of 10 days at 28 ± 2.2 °C and 65±5.7% RH were determined. The least concentration necessary to prevent 50% oxidation (EC50) of β-carotene was found to be 6.53 mg/l, 5.84 mg/l and 524 μg/l respectively for C. anisata, P. glandulosus and butylated hydroxytoluene (BHT) which was the control. On the other hand, the reducing power of the different oils in a decreasing order was found to be P. glandulosus (EC50=2.41) > C. anisata (EC50=1.77 mg/l) while the EC50 of Scavenging abilities were 2.66 and 3.02 mg/l for C. anisata and P. glandulosus respectively. Based on the conjugated dienes profile, the essential oils showed higher antioxidant activity compared to Butylated hydroxytoluene (BHT) activity. The effective time (ET50) of the formulation ranging from 300 to 1000 ppm varied from 2 to 8 days for C. anisata and from 3 to 11 days for P. glandulosus. For the control (BHT), the effect varied from 5 to 15 days at an exposition temperature of 50 °C.Key words: Antioxidant activity; Clausena anisata; Plectranthus glandulosus; Stored products; Scavenging ability; Reducing powe

Optimization of Jatropha curcas pure vegetable oil production parameters for cooking energy

The extraction of vegetable oil from Jatropha from the Tanzanian variety with a fat content of 33.84 ± 2.58% and a moisture content of 5.4 ± 1.97%, was made using two methods: the traditional and the mechanical extraction method. The traditional consists in extracting the oil from the paste using boiling water as a solvent. While the mechanical consists of directly pressing the seeds of Jatropha using a ram press called Bielenberg press, to extract the oil contained in the seeds dried or heated before. The net yield of oil extraction by the traditional method was 22.02 ± 2.1%, with a oil cake percentage of 67.02 ± 3.3% and the ratio water/paste in mass adopted was 0.36. Mechanical extraction has an average raw yield of 26.15 ± 2.74%, with a recovery rate of 74.71%. After decanting for 10 days and filtration, the net yield was 15.39 ± 2.82% with a decantation and filtration rate of 58.67 ± 7.24%. The oil produced by traditional method has a water and volatile content of 1.01 ± 0.05% and a density of 0.884. The one produced by mechanical extraction has 0.19 ± 0.09% and a density of 0.891. The result of combustion test using two burners and one stove showed that the combustion rates were: 0.177 ± 0.034 g/min for the burner using one flame and 1.06 ± 0.04 g/min for the six flame burner and finally 3.07 ± 0, 4 g/min for the ten-flame stove. This ten-flame stove allowed 3 L of water to be boiled at 100 °C for 32 min, although during combustion it was observed a release of black fumes which indicates incomplete combustion with Jatropha in this Stove. The cost of the liter of Jatropha oil obtained is higher compared to fossil fuels such as petroleum (500 FCFA per liter) and gas oil (624F CFA per liter). It would be possible to use vegetable oil from Jatropha as a cooking fuel. Keywords: Vegetable oil, Jatropha, Traditional extraction, Mechanical extraction, Bielenberg pres

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

Chronic Toxicity Of Essential Oils Of 3 Local Aromatic Plants Towards Sitophilus Zeamais Motsch (Coleoptera : Curculionidae)

peer reviewe

Tribolium castaneum (Coleoptera: Curculionidae) sensitivity to repetitive applications of lethal doses of imidacloprid and extracts of Clausena anisata (Rutaceae) and Plectranthus glandulosus (Lamiaceae)

Nowadays, chemical control strategies in crop protection are mostly based on biopesticides or on low persistence synthetic molecules. These tools are alternatives of some products exhibiting adverse effects on consumers and polluting environment. Biopesticides made of essential oils of aromatic plants are more and more advised as user and environmental friendly crop protectants. Few works reviewed consequences of their repetitive use on the capability of the pest to resist to their insecticidal efficiency. The present work was carried out to compare the variation in the efficiency of a synthetic insecticide, imidacloprid and essential oils of Clausena anisata (Rutaceae) and Plectranthus glandulosus (Lamiaceae) against the flour beetle Tribolium castaneum (Coleoptera: Tenebrionidae), during 4 generations (F4). The lethal dose of these insecticides that causes 80% of mortality (LD80) at the first generation killed at the 3rd generation, 60% of pest for the two essential oils and 25% for imidacloprid. At the 4th generation, 25% of the pest populations were killed by the essential oils and 5% by imidacloprid applications. Egg and post-ovum development time differed among generations (P < 0.001). However, the fecundity of sensitive females was greater than that of resistant ones treated with essential oils. Insects treated with imidacloprid exhibited important fecundity in advanced generations. The LD50 level of the F4 treated with imidacloprid is 10 times that of the parental generation; however, the increase doubled from the parent to the F4 while treated with the essential oils. This work showed that T. castaneum could acquire resistance to imidacloprid faster than to 2 tested essential oils. © 2010 International Formulae Group. All rights reserved.Keywords: Chemical control, Essential oils, Imidacloprid, Susceptibility, Stored products, Tribolium castaneum

Effect of supplementation of Pennisetum purpureum to high protein concentrate on growth of guinea pigs (Cavia porcellus) females in western Cameroon

The effect of supplementation of Pennisetum purpureum (Pp) to protein concentrate (PB) on the growth performance Cavia porcellus (L. 1758) was evaluated for 2 months at the application and Research of the University of Dschang (West-Cameroon). 16 guinea-pigs with a average weight of 281 ± 42.0 g were used randomly in four treatments T0 (Pp), T1 (Pp + 16% PB), T2 (Pp + 17% PB) and T3 (Pp + 18% PB). Chemical analysis showed that the different food formulations are rich in protein (16 to 18%), crude fiber (10%), metabolizable energy (2827 to 2857 Kcal/KgMS), calcium (0.95%) and phosphorus (0.58%). Results of the growth parameters showed that mean weights of animals increased significantly (P <0.05) between treatments. Food consumption increased with the age of animals. Guinea-pigs of the control batch T0 (8704.5 ± 0.00 g) consumed more than those of other treatments. The average daily gain varied significantly (P <0.05) between treatments. The consumption index is high for animals of the T0 batch (96.2 ± 7.80) as against 66.8 ± 35.6; 52.3 ± 14.3; 60.4 ± 22.4 respectively for batches T1, T2 and T3. The treatment T1 was the best ration

Protection des stocks de poissons secs en Afrique sub-saharienne

An effective solution to malnutrition in sub-Saharan Africa is the promotion and increasing consumption of fish. This very rich food is a very highly perishable commodity, which the local fisherman loses if no processing measures are taken. A fairly rare and old bibliography shows that é&amp; species of fish caught in the northern regions of Cameroon undergo an artisanal transformation in order to extend the shelf life and preserve its quality and food potential. Unfortunately, despite these approaches, many loss factors such as insect pests, mites and fungi, rotting agents, cause significant losses to dry fish during storage. Dry fish comes from an artisanal drying and smoking process. To avoid these losses, the fish during processing and storage is treated with chemical formulations from 22 active ingredients, some of which are extremely dangerous. An alternative to these dangerous pesticides is to include in the processing ingredients of fish, spice plants of which 14 locally available have proven insecticidal, fungicidal or acaricidal properties. With a view to developing tools to protect dry fish stocks by limiting consumer intoxication and environmental pollution, there is an urgent need for more detailed studies to be carried out with the aim of developing energy-efficient transformation processes, which incorporate natural insecticides as alternatives limiting natural or industrial contamination and providing a healthy and safe food. Keywords: Dry fish, Loss factors, Pesticides, Storage, AlternativesUne solution efficace à la malnutrition en Afrique sub-saharienne est la promotion et la consommation de plus en plus accrue du poisson. Cet aliment très riche est une denrée très hautement périssable, que le pécheur local perd si aucune mesure de transformation n’est entreprise. Une bibliographie assez rare et ancienne montre que 21 espèces de poisson péchées dans les régions septentrionales du Cameroun subissent une transformation artisanale dans le but de prolonger la durée de conservation et d’en préserver la qualité et le potentiel alimentaire. Malheureusement, malgré ces démarches, de nombreux facteurs de pertes comme les insectes ravageurs, les acariens et les champignons, agents de pourriture, causent d‘importantes pertes au poisson sec au cours du stockage. Le poisson sec est issu d’un processus artisanal de séchage et ou de fumage. Pour limiter ces pertes, le poisson au cours de la transformation et pendant le stockage est traité par des formulations chimiques issues de 22 matières actives dont certaines sont extrêmement dangereuses. Une solution alternative à ces pesticides dangereux est d’inclure dans les ingrédients de traitement du poisson, des plantes à épices dont 14 localement disponibles ont des vertus insecticides, fongicides ou acaricides avérées. En vue du développement des outils de protection des stocks de poissons secs en limitant l’intoxication du consommateur et la pollution environnementale, il y a urgence que des études plus fines soient menées dans le but de développer des procédés de transformation économes en énergie, qui en intègrent des insecticides naturels comme alternative limitant les contaminations naturelles ou industrielles et fournissant un aliment sain et sûr. Mots clés: Poisson sec, facteurs de pertes, pesticides, stockage, alternative