Diversité des ravageurs des denrées et méthodes alternatives de lutte en milieu tropical

Diversity of Stored Grain Pests and Alternative Methods for their Control in Tropics. The major cause of important post-harvest losses in northern Cameroon is due to the attacks of insects pests. These beetles (Insecta: Coleoptera) during their development depreciate food in storage, they are able to destroy a whole stock in a very short period of time. To protect stored products against these insects, synthetic insecticides and many other biological or physical methods are used, very important amount of work had been carried out on this subject. This review summarises the importance and the diversification of stored grain pests in Cameroon and presents current methods. Hence, the review highlights the use of the essential oils from spices as an important user and consumer friendly method to protect grain in storage

Predation of Myrmeleon obscurus (Navas, 1912) (neuroptera: Myrmeleontidae) on the ground ant Myrmicaria opaciventris emery (Formicidae: yrmicinae)

comprehension of the feeding behaviour of this pit building sit-and-wait predator. The predatory behaviour observed after a 24-hour starvation, pointed out that a 3rd instar larva of Myrmeleon obscurus (NAVAS, 1912) needs 90.7±2.54 min for its first predation on the ground ant Myrmicaria opaciventris EMERY (Formicidae : Myrmicinae). For the following ones, only 54.83 ± 12.9 min is allocated to the predation on a single prey. Thepredation is made up of 4 main steps: capture and subduing, suction, removal of mandibles and abandonment of remains of the prey. Maximizing predation is a strategy for these seasonal insects to store energy that might help them to survive during the unfavourable rainy season.© 2010 International Formulae Group. All rights reserved.Keywords: Ant lion larvae, Cameroon, mandibles, feeding behaviour, handling time

Potentialisation de l’efficacite insecticide des poudres de feuilles ou amandes de neemier Azadirachta indica A. Juss par formulation avec la cendre de tiges de mil contre Sitophilus zeamais motsch. Et Sitophilus oryzae L. (Coleoptera : Curc

Dans la vallée du Logone (Extrême-Nord du Cameroun et Sud-Ouest du Tchad en Afrique Centrale) où l’activité agricole est prépondérante, l’utilisation des pesticides chimiques est importante alors que de nombreuses ressources locales peuvent être des alternatives aux pesticides chimiques conventionnels. Les populations de cette localité continuent à faire recours aux  insecticides conventionnels dangereux dans la lutte contre les insectes ravageurs qui occasionnent des pertes considérables aux denrées et semences au cours de leur stockage. L’utilisation des outils traditionnels reste encore archaïque et non standardisée. Le but de ce travail est de déterminer le potentiel insecticide des formulations poudreuses des parties du neemier Azadirachtaindica A. Juss (Meliaceae) et de la cendre des tiges de mil contre les insectes ravageurs des céréales stockées. Pour ce faire, ce potentiel a été mis en évidence par l’évaluation des propriétés insecticides des feuilles et des amandes du neemier en formulation avec la cendre de tiges de mil sur Sitophilus zeamais Motsch., Sitophilus oryzae L. (Coleoptera : Curculionidae). De ces investigations, il ressort que les doses 5 % ; 10 % ; 15 % et 20 % de cendre ont induit respectivement chez S. oryzae 19,97a±3,50 %, 83,32±4,58b %, 95±8,66c % et 100±0c % de mortalité (F=279,95***, ndl=23) contre 25,15±5,19a %, 86,25±10,82b %, 100±0c % et 100±0c % chez S. zeamais (F=213,84***, ndl=23). Quant aux formulations équilibrées, les traitements CF10 et CG10 ont induit  respectivement 88,64±8,20a % et 94,06±3,54a % de mortalité de S. oryzae contre 96,25±7,40a% et 93,75±6,50a % chez S.zeamais. Quant aux formulations disproportionnées, les traitements  /4CF10 et 1/4CG10 ont induit respectivement 95,18±5,33a % et 93,75 ±6,50a% de mortalité chez S. oryzae contre 93,75±7,40a % et 87,50±5,60a % de S. zeamais respectivement. Les traitements1/4CF10 et 1/4CG10 sont les plus actifs sur les deux insectes ravageurs. Le développement d’un bio insecticide fait d’une formulation des poudres de feuilles et d’amandes de neemier et de la cendre de tiges de mil pourrait être utilisé pour le contrôle des insectes ravageurs des céréales au cours du stockage dans la Vallée du Logone.Mots clés : Insectes ravageurs, denrées stockées, bio insecticides, neemier, tiges de mil, cendre, formulations poudreuses, Vallée du Logon

Stratégies organisationnelles d'intégration des TIC dans l'enseignement secondaire au Cameroun : étude d'écoles pionnières

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal

Potential use of essential oils from local Cameroonian plants for the control of red flour weevil 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 castaneun. 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.Key words: Essential oils, Tribolium castaneum, Pesticides

Habitats of antlions larvae (Neuroptera: Myrmeleontidae) in the Sudano-Guinean and Sudano-Sahelian zones of Cameroon

Antlions (Insecta: Neuroptera) are flying insect associated with sunny weather at adult stage. During larval stage, xerophilous insects they are familiar to arid soils with critical temperature, hygrometry and luminosity. These 3 climatic parameters are used to discriminate among larval habitats of antlions in the Soudano Guinean and Soudano Sahelian Savannah of Cameroon. Investigations made during 3 years from 2015 to 2018,consisted in survey of larvae’s funnels. At the level of each active pit-traps, the 3 parameters were recorded during the whole dry season. Analysis of data computerised pointed out that larvae of Cueta bourborni Navas 1935, and those of Cueta sp, are frequent within sites that are warm (40.57±0.64°C to 52.14±4.08°C); dry (10.91±0.82-16.81±2.74%rh) and lighted (94380.2 ±16109.4 lux) habitats. On the other hand, larvae of Myrmeleonquinquemaculatus Hagen 1853 are associated with sites that are: humid (75.46±4.50% RH), cloudy (448.232±300. 491 lux) with tendency to moist (22.11±0.88°C to 28.10 ±2.14°C). Presence of C. bourbonni sometimes in the moisty Soudano Guinean zone could only indicate episode of warming. Keywords. Antlions habitats, global warming, temperature, luminosity, Hygrometr

Bioactivity of flours of seeds of leguminous crops Pisum sativum, Phaseolus vulgaris and Glycine max used as botanical insecticides against Sitophilus oryzae Linnaeus (Coleoptera: Curculionidae) on sorghum grains

Cereals occupy an important place in the solving of food insecurity problems in the northern Cameroon. Chemicals continue to be the main tools to protect cereals during storage in spite of the deleterious effects due to their current usage. Nowadays, entomotoxic proteins of seeds of leguminous are more and more considered as alternative insecticides. Efficacy of crude flours of four legumes seeds, applied to the sorghum grains, was evaluated against Sitophilus oryzae L. (Coleoptrea: Curculionidae) by contact-ingestion. This research revealed that flours of bean and pea are very active on S. oryzae. The lethal dose 100 (LD100) and the lethal times 100 (LT100) are respectively 5 g and 20 days for pea’s flour and 10 g and 50 days for bean’s flour. The toxicity of flours’ seeds increased with the dose and the duration of application (F=169.734***, Df =6; 28). During a period of 90 days, the flours of P. sativum and P. vulgaris keep their insecticidal activities, showing constant mortality rates for bean (F= 2.325ns, Df =6; 28) and for pea (F=1,91ns, df= 34). The flours of seeds of P. sativum and P. vulgaris at the weight ratio of 5 % and 10 % respectively can provide protection of sorghum grains against the attack of S. oryzae. The legumes seeds are the alternative active ingredients to hazardous conventional insecticides.Keywords: Cereals; leguminous plants; entomotoxic proteins; persistence; Sitophilus oryzae

Diversity of processes for transformation of fresh fish in Northern Cameroon

Fish as a foodstuff of high nutritional value is considerably perishable. It must be transformed in order to improve the duration of its conservation. Drying and smoking are the most popular processes to transform fish in northern Cameroon. These steps usually affect the quality of the finished products. In order to improve the quality of locally transformed fish in a handmade manner and to typify such activity, an survey was conducted in three fishing ponds in the Northern part of Cameroon with 160 fishermen and fish transformers. It appears that the technique of transforming fish in those main fishing ponds in Northern Cameroon vary at the level of preprocessing and dehydration phases of fresh fish. Smoking is done in a traditional oven followed by cleaning (4.1% in the Adamawa Region and 33.0% in the North and Far North Region) or flaking of the fish (95.9% in Adamawa and 61.1% in the North and the Far North Region). Then, come emptying (95.9% in Adamawa and 61.1% in the North and Far North), cutting into small pieces (11.1% in the Far North) or cracking (82.6% in the Adamawa Region). At the end, washing (95.9% in the Adamawa and 72.2% in the North and Far North), spinning (100%), smoking (100%) and then packaging of the fish (100%) complete the process. All these operations are conducted without equipment for protection, on uncleaned surfaces and with irregularly washed materials with clean water. The drying process is done on bare ground on top of a drying stall is a constant step in the Far North (54.9%) and North (28.6%) regions and scarce in the Adamawa region (9.3%). A particular emphasis should be laid on hygienic measures to ensure a sanitary quality of dry fish at the end of both smoking and drying processes. Keywords: Processing, smoking, drying, Northern Cameroon, Transformatio

Pratiques Paysannes De Production Durable Des Graines De Voandzou [Vigna Subterranea (L.) Verdc.] Pour La Sécurité Alimentaire Dans Le Cameroun Septentrional

Bambara groundnut is a leguminous plant with high nutritive value of Sub Saharan Africa. In spite of its high potential in alimentation, the Bambara groundnut is less popularized. This crop grows on acid, dry and less fertile soils and may therefore be a resilient crop in the context of climatic variability. The present work aims to identify of all the morphotypes of this culture and the usual tools of conservation of its seeds during the storage process. Investigations carried out during 3 agricultural campaigns showed that women more than 40 years old represents more than 98% of producers of Bambara groundnuts in northern Cameroon. The production concerns 54 morphotypes use as food or as medicinal plants. During storage of grains of this legumes, the major pest is the bruchid Callosobruchus maculatus Fab. (Coleoptera : Chrysomelidae). Under traditional production way, the limitation of the postharvest losses due to this pest is done either by the use of 21 local plants as botanical insecticide or by the use of 25 industrial chemical pesticides