Fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) and southern armyworm (SAW) Spodoptera eridania (Stoll) have become major threats to crops in Africa since 2016. African governments adopted emergency actions around chemical insecticides, with limited efforts to assess the richness or roles of indigenous natural enemies. Field surveys and laboratory studies were conducted to identify and assess the performance of parasitoids associated with spodopterans in Cameroon. FAW was the most abundant spodopteran pest. Telenomus remus (Nixon), Trichogramma chilonis (Ishi), Charops sp. (Szépligeti), Coccygidium luteum (Cameron), Cotesia icipe (Fernandez & Fiaboe), and Cotesia sesamiae (Cameron) are the first records in the country on spodopterans. Telenomus remus, T. chilonis, C. icipe, and Charops sp. were obtained from both FAW and SAW; C. luteum and C. sesamiae from FAW. The distribution of spodopterans, their endoparasitoids, and parasitism rates varied with host, season and location. In the laboratory, T. remus showed significantly higher parasitism on FAW than SAW, and significant differences in the development parameters between the two host eggs, with shorter development time on FAW. It induced significant non-reproductive mortality on FAW but not on SAW. Developmental parameters showed that C. icipe has a shorter development time compared to other larval parasitoids. Implications for conservative and augmentative biocontrol are discussed.

This study was conducted in 2015 in Ndop, Ngoketujia Division in the North-West region of Cameroon. Four varieties of rice were used: NERICA3, NERICA7 (upland rice), NERICA36 and NERICA42 (lowland rice). Two types of fertilizers N-P-K (23-10-05 and N-P-K (20-10-10) were tested at different doses (0 kg-contol; 180 kg, 200 kg, 220 kg-treatments). The trial was set up in a Randomized Complete Block Design (RCBD) in a manner following conventional methods. Application of fertilizers was done at 21 and 51 days after planting (DAP). The growth parameters were evaluated weekly while yield parameters were collected at maturity. The fertilizer N-P-K (23 10 05) gave a better growth with appropriate doses compared to N-P-K (20 10 10) in all the varieties used in this study while fertilizer N-P-K (20 10 10) gave a better yield than N-P-K (23 10 05) in the same varieties. In terms of output of rice, fertilizer N-P-K (20 10 10) proves better at dose 200 kg than fertilizer N-P-K (23 10 05) at the same dose. For good growth and yield the use of appropriate doses of fertilisers will significantly improve the yield of rice. Key words: Rice varieties, fertilisers, fertilizers doses.

Control of fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) since its invasion of Africa still depends on pesticides. Early detection of adults is considered the key to the success of larvae control in the crop field. However, FAW control thresholds based on current monitoring techniques are not well established in Africa. We investigated the efficacy of moth capture frequencies and FAW incidence levels as decision tools for FAW management. Experiments were conducted over two maize cropping seasons during which FAW incidence, severity, and larvae count were recorded during destructive sampling after the application of a homologated insecticide. During the first season, the FAW incidence ranged from 37.5 ± 5.6% in the 25% incidence threshold treatment to 48.1 ± 8.1% in the control. During the second season, the incidence was significantly lower in the 25% incidence threshold treatment (55.8 ± 5.7%) compared with the control (75.7 ± 3.0%). Over the two seasons, no significant difference in FAW damage severity was recorded between the treatments and control. The highest number of larvae per plant (4.0 ± 0.6) was observed in the 10% incidence threshold treatment. Insecticide application did not consistently contribute to reducing FAW incidence and observed plant damage did not translate into yield loss. FAW control needs further investigation to establish a threshold above which damage translates into yield loss, thus necessitating control intervention.

Okra contributes an important part of the diet to many people in the tropics, more especially in Cameroon. But its production is seriously affected by poor soil fertility. In other to mitigate this problem, a field experiment was conducted from April to august 2016 at Institute of Agricultural Research for Development (IRAD) Nkolbisson-Yaoundé with the main objective to evaluate the effects of different soil amendments on the performance of okra (Abelmoschus esculentus L.) crop. The experiment was laid out using a randomized complete block design (RCBD) with three replications and eleven treatments: (Tithonia leaves (6700 kg/ha), piggery manure (6700 kg/ha), foliar fertilizer (0.6 kg/ha), urea (200 kg/ha), NPK20-10-10 (200 kg/ha), Tithonia leaves (3350 kg/unit) + NPK20-10-10 (100 kg/unit), Tithonia leaves (3350 kg/unit) + Urea (100 kg/ha), urea (100 kg/ha) + NPK 20-10-10(100 kg/ha), Tithonia leaves (100kg/ha) + foliar fertilizer (0.3 L/ha), Tithonia leaves (3350 kg/ha) + piggery manure (3350 kg/ha) and control (0 kg/ha). The Results showed that the growth and yield of okra were significantly (P<0.05) affected by different soil amendments. The number of days to achieve 50% shoot set was significantly (P<0.05) greater (50.66±1.24) with the use of NPK 20-10-10 as compared to the rest of the treatments. The number of days to achieve 50% flowering was significantly (P<0.05) greater (59.33±1.46) with the use of Tithonia leaves as compared to the rest of the treatments. The tallest plants and highest number of fruits per plant were recorded from the urea treatment, while the use of foliar fertilizer resulted in many branches and leaves per plant. A combination of NPK and Tithonia leaves resulted in heavy fruits per plant. NPK treatments produced the highest number of fruits and the heaviest fruits as compared to the foliar and control treatments. From the results obtained, it can be concluded that the application of foliar fertilizer, urea and NPK 20-10-10 + Tithonia and NPK which recorded the highest growth and yield parameters among all the treatments are the best treatments and should be adopted by farmers in the study area to maximize their yields. However, further studies on other combinations of organic fertilizers need to be carried out in different areas in order to come out with desired new alternatives that will reduce the use of high quantity of inorganic fertilizers. Key words: Performance, soil amendments, okra, bimodal, fertilizer.

The study was conducted in the research field sites of the Institute of Agricultural Research (IRAD), Bambui, North West Region, (IRAD), Ekona South West Region and the International Institute of Tropical Agriculture (IITA) Nkolbisson, Yaoundé, Center Region of Cameroon. Four cultivars of taro (Dark green petiole with small leaves (L1), Red petiole with small leaves (L2), Light green petiole with large leaves (L3) and Light green petiole with small leaves(L4)) were planted in four seasons, for two years, in the months of March and July 2015, March and July 2016 in all the research farms. Ninety corms of the each cultivar were treated before planting with fungiforce at 0.33% concentration while others were not treated. Fungiforce is a contact and systemic fungicide containing high levels of copper oxide (600 grams) and mild levels of metalaxyl (120 grams), various concentrations of 0.4%, 0.33%, 0.27%, at the onset of the first symptom of leaf blight on the leaves using knapsack sprayer of 15 litres at two weeks interval, while the control experiment consisted of unsprayed taro leaves. Data for the disease incidence of taro leaf blight was recorded from the onset of disease in fields and continued at two weeks interval for 6 weeks. The results of planting taro in four seasons in three experimental field sites revealed that there was a decrease in disease incidence in fields sprayed with fungiforce than in the control field. Plots sprayed with fungicide at different concentrations showed no variation on the 4 cultivars in the different field sites. The disease incidence ranged from 10% to 100% in the 4 seasons, at the three experimental field sites. The variation in disease incidence in the three planting sites is an indication of possible genotypes by environment (GXE) interaction that may have significant influence on the taro leaf blight resistance potential.

La pollution de l’environnement demeure l’un des problèmes majeurs découlant du développement technologique. Le rejet d’eaux usées contenant ce polluant dans l’environnement sans traitement préalable a de graves conséquences pour les êtres vivants. L’objectif de cette étude était d’utiliser des coquilles d’arachides pour éliminer le BPA dans les eaux usées, où, les spectres infrarouges et les diffractogrammes des matériaux ; et autre méthodes ont été spécifiquement étudiées. Dans cette étude, le plan composite central a été utilisé pour optimiser les facteurs qui affectent l’adsorption du BPA de la solution. Ces facteurs comprennent la concentration initiale, la le pH de la solution, le temps de contact, et la masse de carbone sur la réponse qui est l’adsorbé quantité de BPA. Les valeurs respectives de pH et de pHpzc sont de 5,99 et 6,34 pour les PAB; 6.24 et 7.35 pour les PAN et 6,38 et 6,58 pour les PAU. Des études cinétiques ont trouvé l’Elovich et le pseudo-second les modèles cinétiques d’ordre expliquent mieux le mécanisme d’adsorption des PAB, PAN et PAU. Cordialement aux isothermes d’adsorption, les isothermes de Langmuir, Langmuir-Freundlich et Redlich-peterson ont montré une meilleure capacité d’adsorption pour la biosorption du BPA en solution aqueuse par les PAB, PAN et PAU en ce qui concerne les valeurs du coefficient de corrélation et des erreurs. Environmental pollution remains as one of the major problems arising from technological development. The discharge of waste water containing this pollutant into the environment without prior treatment has serious consequences for living beings. The objective of this study was to use peanut shells to eliminate BPA in waste water, where, the infrared spectra and diffractograms of materials; and other methods were specifically studied. In this study, the central composite design was used to optimize the factors that aûect the adsorption of BPA from solution. These factors include initial concentration, the pH of the solution, the contact time, and the mass of carbon on the response which is the adsorbed quantity of BPA. The respective pH and pHpzc values are 5.99 and 6.34 for the PABs; 6.24 and 7.35 for the PANs and 6.38 and 6.58 for the PAUs. Kinetic studies found the Elovich and pseudo-secondorder kinetic models better explain the adsorption mechanism for PABs, PANs, and PAUs. With regards to the adsorption isotherms, the Langmuir, Langmuir-Freundlich and Redlich-peterson isotherms showed a better adsorption capacity for the biosorption of BPA in aqueous solution by PABs, PANs and PAUs with regard to the values of the correlation coefficient and errors.