Bøger af Ismael Sadou

Na zona de Meskine (Maroua, Camarões), foram efectuadas observações (estação seca) sobre espécies inventariadas de Hoverflies em função da diversidade dos recursos alimentares disponíveis. O principal objetivo era encontrar conhecimentos entomológicos que pudessem facilitar o aumento dos rendimentos nas práticas agrícolas, preservando simultaneamente o ambiente no local agrícola. Os inquéritos foram efectuados de três em três dias sob a forma de transectos. As espécies de plantas atractivas para os Syphidae são removidas e o papel funcional de cada espécie de Hoverfly é determinado. Os resultados obtidos permitiram identificar 21 espécies de moscas varejeiras. Estas espécies foram agrupadas em 8 géneros, dos quais se destaca o género Eristalinus com 12 espécies. Outros géneros foram reduzidos a 40%, nomeadamente Toxomerus, Melanostoma, Phytomia, Mesembrius, Asarkina, Paragus e Episyrphus. Foram determinados três grupos com base na frequência de ocorrência destes Syrphidae: espécies constantes, espécies incidentais e espécies acidentais. As visitas florais das moscas listadas foram avaliadas em 26 espécies de plantas, incluindo 8 culturas camponesas fora de época e 20 espécies em torno e entre o espaçamento entre linhas das culturas.

Dans la zone de Meskine (Maroua, Cameroun), des observations ont été faites (saison sèche) sur des espèces d'inventaire de syrphes en fonction de la diversité des ressources alimentaires disponibles. L'objectif principal était de trouver des connaissances entomologiques pouvant faciliter l'augmentation des rendements dans les pratiques agricoles tout en préservant l'environnement dans le site agricole. Les relevés ont été effectués tous les trois jours sous forme de transect. Les espèces végétales attractives pour les Syphidae sont éliminées et le rôle fonctionnel de chaque espèce de syrphe est déterminé. Les résultats obtenus ont permis d'identifier 21 espèces de syrphes. Ces espèces ont été regroupées en 8 genres dont le genre Eristalinus est prépondérant avec 12 espèces. Les autres genres ont été réduits à 40%, à savoir Toxomerus, Melanostoma, Phytomia, Mesembrius, Asarkina, Paragus et Episyrphus. Trois groupes ont été déterminés en fonction de la fréquence d'apparition de ces Syrphidae: les espèces constantes, les espèces incidentes et les espèces accidentelles. Les visites florales des mouches répertoriées ont été notées sur 26 espèces végétales dont 8 cultures paysannes hors saison et 20 espèces autour et entre les interlignes des cultures.

Nella zona di Meskine (Maroua, Camerun), sono state effettuate osservazioni (stagione secca) su specie di sirfidi in inventario a seconda della diversità delle risorse alimentari disponibili. L'obiettivo principale era quello di trovare conoscenze entomologiche che potessero facilitare l'aumento dei rendimenti nelle pratiche agricole, preservando al contempo l'ambiente nel sito agricolo. I rilievi sono stati effettuati ogni tre giorni sotto forma di transetto. Sono state rimosse le specie vegetali attrattive per i sifidi ed è stato determinato il ruolo funzionale di ciascuna specie di sirfidi. I risultati ottenuti hanno permesso di identificare 21 specie di Sirfidi. Queste specie sono state raggruppate in 8 generi, tra cui spiccava il genere Eristalinus con 12 specie. Altri generi sono stati ridotti al 40%: Toxomerus, Melanostoma, Phytomia, Mesembrius, Asarkina, Paragus ed Episyrphus. In base alla frequenza di presenza di questi Syrphidae sono stati determinati tre gruppi: specie costanti, specie accidentali e accidentali. Le visite floreali delle mosche elencate sono state valutate su 26 specie vegetali, tra cui 8 colture contadine fuori stagione e 20 specie intorno e tra le file delle colture.

In der Zone von Meskine (Maroua, Kamerun) wurden Beobachtungen (Trockenzeit) zu inventarisierten Arten von Schlupfwespen gemacht, die von der Vielfalt der verfügbaren Nahrungsquellen abhängen. The main goal was to find Entomological knowledge which can facilitate the rise in yields in agricultural practices while preserving the environment in the agricultural site. Die Erhebungen wurden alle drei Tage in Form von Transekten durchgeführt. Attraktive Pflanzenarten für die Syphidae wurden entfernt und die funktionelle Rolle jeder Art von Hoverfly bestimmt. The results obtained helped to identify 21 species of Hoverflies. These species have been grouped in 8 genuss of which the genus Eristalinus was prominent with 12 species. Other genus were reduced to 40% namely Toxomerus, Melanostoma, Phytomia, Mesembrius, Asarkina, Paragus and Episyrphus. Aufgrund der Häufigkeit des Auftretens dieser Syrphidae wurden drei Gruppen bestimmt: konstante Arten, zufällige und unfallbedingte Arten. Die Blütenbesuche der aufgelisteten Fliegen wurden an 26 Pflanzenarten gemessen, darunter 8 Bauernkulturen außerhalb der Saison und 20 Arten um und zwischen den Reihenabständen der Kulturen.

The chemical fight against insects pest causes many problems on the biodiversity of ecosystems, destabilizes the trophic level of the ecosystem and has harmful effects on the on health human. Mean while the biological fight using plants extractions can equally play the same role of killing pest, reason why the present study which was carried out in the irrigated perimeters of Maga in the Far North region of Cameroon, have as principal objective to evaluate the aqueous extraction of neem fruit on the insects pest of rice. The specific objectives were to know the biological diversity of insect pest in the irrigated perimeters of Maga, and their repartitioning in the phenological stages, again, to see the effects of the aqueous extractions of the neem fruits on the insects pest per variety and in function of the phenological stages, also to evaluate the damages cause by insects pest during the talling stage in function of the varieties, finally, to evaluate loss cause by the insects pest. The study was made on two rice varieties which were IR46 and NERICA3 in a split plot disposition. The biological fight have shown an effectiveness in the nursery, talling.

In the zone of Meskine (Maroua, Cameroon), observations have been made (dry season) on inventory species of Hoverflies depending on the diversity of food resources available. The main goal was to find Entomological knowledge which can facilitate the rise in yields in agricultural practices while preserving the environment in the agricultural site. The surveys were made every three days in the form of transect. Attractive plant species for the Syphidae are removed and the functional role of each species of Hoverfly determined. The results obtained helped to identify 21 species of Hoverflies. These species have been grouped in 8 genuss of which the genus Eristalinus was prominent with 12 species. Other genus were reduced to 40% namely Toxomerus, Melanostoma, Phytomia, Mesembrius, Asarkina, Paragus and Episyrphus. Three groups have been determined based on the frequency of occurrence of these Syrphidae: constant species, the incidental and accidental species. Floral visits of the flies listed were rated on 26 plant species including 8 peasant crops off season and 20 species around and between the line spacing of the cultures.

Insect pests of rice are a very serious threat to rice production (irrigated and rainfed) in the Far North region of Cameroon, causing yield losses, but have not received the attention they deserve as a major constraint to rice production in Africa. The present study was conducted with a view to improving rice production through proper management of rice insect pests, using appropriate control methods in the Far North of Cameroon in the irrigated rice ecosystem of Maga and the rainfed rice ecosystem of Maroua. On experimental plots (randomized blocks) of NERICA 3 rice and IR 46 rice, we compared three treatments: a control (no pesticide application), a registered chemical insecticide "lynx" whose active ingredients are Lambda-cyhalotrin 15g/l and Acetamiprid 20g/l, and a biopesticide "aqueous neem seed extract". Spraying the aqueous extract of neem seeds on the IR46 rice variety and the NERICA 3 variety enabled us to better control the evolution of the population of insect pests such as Conocephalus maculatus.

In order to increase rice production while preserving the environment, we tested the influence of some inocula on the growth of two irrigated rice varieties in the presence and absence of chemical fertilizer. The study showed that arbuscular mycorrhizal fungi accelerate the germination rate and increase the emergence rate of rice seeds. In addition, inoculation with mycorrhizal biofertilizers significantly increased the size of rice plants. The best performing inocula for germination rate are Tropic Mix and Glomus clarum. The experimental inocula performed best for seed emergence rate, plant height, and fresh and dry biomass. FKR56 was the variety that developed better performance compared to IR46. We also find that growing rice in the presence of arbuscular mycorrhizal fungi and chemical fertilizer does not significantly differ from growing it with arbuscular mycorrhizal fungi alone.

The present study on the effect of insect pests on rice production was conducted in Maroua, Far North Cameroon in the rainfed rice ecosystem to determine the biological diversity of insect pests of rice to improve rice production. Insects were captured using sweep nets throughout the entire plot at different phenological stages of the rice crop, from the 15th day after sowing to heading.The results obtained on biological diversity showed that Maliarpha separatella species (22 species) have a high number. Regarding insect dynamics, a variation in the number of insect pests and predators was observed at different phenological stages of rice.

The objective of the study was to increase rice production by screening three (03) NERICA (New Rice for Africa) rice varieties against African rice midge (Orseolia oryzivora) attack and to integrate efficient biological control in rainfed rice cultivation.During the rice cropping cycle, each phenological stage of the plant is sampled every two weeks using the D-VAC aspirator and mowing net throughout the cropping season, as this sampling frequency corresponds to a specific phenological stage. White hearts were sampled during the bolting stage of the plant. NERICA 3 is more susceptible than the other two varieties because it has a higher AfRGM population. The abundance of the AfRGM population varies according to the collection method (Sweep-Net and D-VAC). Collection using the D-VAC was more efficient than Sweep-Net.Only 5 live AfRGM individuals were recovered out of 38 observed.

This study aims to evaluate the insecticidal activity of some plants from the far north of Cameroon. Leaves and/or barks of four local plants (Azadirachta indica, Boswellia dalzeilii, Khaya senegalensis and Ocimum canum) were harvested, dried and ground into powder for the formulation of insecticidal sticks at different doses. Toxicity tests were carried out on adult Culicidae by fumigation. They revealed low mortality rates after 15 minutes of exposure. The persistence due to the smoke of the sticks leads to high mortality rates after 6 and 24 hours of exposure. Mortality rates increased with dose for each plant species. Lethal doses were calculated 6 hours after exposure for each plant powder. Azadirachta indica leaf powder was the most effective because it had the lowest LD50 value of 36.14%. These plant powders can be used as natural insecticides instead of chemical insecticides.

The present study on the effect of insect pests on rice production was conducted in Maroua, Far North Cameroon in the rainfed rice ecosystem to determine the biological diversity of insect pests of rice to improve rice production. Insects were captured using sweep nets throughout the entire plot at different phenological stages of the rice crop, from the 15th day after sowing to heading.The results obtained on biological diversity showed that Maliarpha separatella species (22 species) have a high number. Regarding insect dynamics, a variation in the number of insect pests and predators was observed at different phenological stages of rice.

Knowledge about local fruit species in the Far North region is scarce. The study on the "Extension of local edible fruit sectors in the Far North region of Cameroon" aims to provide basic data on local fruit sectors. It focuses on four species: Balanites aegyptiaca, Adansonia digitata, Ziziphus mauritiana, Tamarindus indica. 463 people were interviewed in 8 localities in the region, namely: Maroua, Méri, Mindif, Kaélé, Yagoua, Maga, Mokolo, and Rhumsiki. Four types of actors were identified: harvesters, processors, sellers, and consumers. The study estimates the annual harvest of the four fruit species at more than 1,123.4 tons, 85.07% of which is marketed and 14.93% of which is withdrawn from the circuit by the harvesters for self-consumption or due to degradation. The study also shows that the consumption of local fruits represents more than 40% of the overall consumption of fruits in households. It is quite high among children, averaging 8.5 kg/person/year. This demonstrates the importance of local fruit in the fight against food insecurity.

The objective of this study was to make an inventory of predatory and parasitoid arthropods of rainfed rice insect pests in Maroua. Insects were captured using sweep nets in a random fashion over an area of 2500 m2. 100 double sweeps (200 sweeps) were made per net and repeated five times, for a total of 1000 sweeps per collection. Collections were made every two weeks at each stage of rice development (seedling, tillering and heading). Nine species of predators and four species of parasitoids were identified, the most abundant being Araneus sp. of the family Araneidae and Platygaster sp. of the family Platygasteridae. The dynamics showed that the predator population grows rapidly while the parasitoid population decreases during the development of the plant.

This study on the effect of insect pests on rice production was conducted in the Far North of Cameroon in the Maga irrigated rice ecosystem. The aim was to determine the biological diversity of insect pests of rice in the Maga rice ecosystem, to assess the damage and dynamics of insect pests on the phenological stages of rice, and to evaluate the effect of the insecticide lynx on insect pests and rice production. The results obtained on biological diversity showed that 2,465 insect pests of rice were collected on the variety IR 46 and 3,264 on the variety NERICA 3. In terms of insect pest damage, the total insect pest loss was estimated at 49.98%, with 26.30% loss at tillering and 23.68% at harvest on both varieties. The chemical insecticide lynx reduced pests at a rate of 12.585% at nursery, 20.4725% at tillering, 9.305% at heading and 8.7325% at maturity. Yields were obtained at 2.13 t/ha for the variety IR 46 and 1.91 t/ha for the variety NERICA 3.