Citrullus colocynthis (L.) Schrad seeds generally called Egusi melon are widely eaten in Nigeria, but its uses in post-harvest crop protection have not been exploited. The effects of the edible oil of C. colocynthis seeds on Callosobruchus maculatus (F.) were assessed on adult mortality, oviposition, F 1 progeny emergence, cowpea seed damage and seed germinability in the laboratory. Results indicated that the oil showed some lethal effects on treated insects at above 50% mortality and very high reduction in oviposition at increased concentrations. Seeds treated with the oil showed significant (P<0.05) reduction in the number of progeny of C. maculatus. There was no observable feeding damage on seeds treated with the highest concentration of the oil applied. In addition, the oil has no adverse effect on seed viability. The present studies indicate that the application of the oil show promise in post-harvest protection of cowpea seeds.
Shelf-life of five horticultural produce were studied. These include three leafy vegetables: Telfairia occidentalis, Celosia argentea and Amaranthus cruentus and two fruit vegetables: Lycopersicum esculentum and Abelmuschus esculentus. The layout plan of the experiment was a 3x2 factorial in a completely randomized design and each treatment replicated three times. The two factors examined were moisture barrier at three levels namely: thick lining, thin lining and non-lining. The other factor included initial moisture content of the produce, namely, turgid and partially wilted. Partial wilting of the produce was achieved by exposing freshly harvested materials at ambient temperature to dry for 45 min. During this period, about 20% of the moisture content was lost. Eighteen (18) vegetable baskets which work on the principle of evaporative cooling system were used. Each type of produce was stored at a time inside the vegetable basket. Some quantity of each produce were kept on the laboratory benches to serve as controls. Data recorded includes length of storage of produce, severity of disease infection, visual quality, disease incidence, ambient temperature and relative humidity of the storage baskets. The result indicates that there was a significantly higher relative humidity (P< 0.05) in the lined baskets than in the non-lined baskets. Consequently, the shelf-life of produce in lined basket was prolonged. Turgid produce had better quality retention and stored much longer than partially wilted produce. Generally, the evaporative coolant baskets provided an average temperature of 3°C lower than the ambient condition. The shelf-life of leaf vegetables T. occidentalis, C. argentea and A. cruentus was extended appreciably for 78 days compared to the controls.
Post-harvest losses due to insect pest infestation in storage constitute a challenge to sustainable food security and economic losses to farmers throughout the world. Use of synthetic chemicals have been the most effective means of reducing losses in storage. Unfortunately, these toxicants have adverse effects in humans and the environment. There is renewed search for safer plant products as alternatives. In this study, we assessed the potential use of Piper guineense seed oil in the control of cowpea bruchid, Callosobruchus maculatus (F.) infestation on stored cowpea seeds. Adult mortality, oviposition rate, F1 progeny emergence, cowpea seed damage and seed germinability were the indices considered in the assessment under laboratory conditions. The setup of the experiment was completely randomized design (CRD). Statistical analysis of the data was by analysis of variance (ANOVA). Adult C. maculatus mortality was dose-dependent with higher dosages inducing 100% mortality. The number of eggs laid on the treated seeds were significantly (P<0.001) reduced. Progeny emergence and feeding damage were completely inhibited at higher dosages. The seed oil has no adverse effect on cowpea seed viability. The results indicated that P. guineense seed oil has protectant potential against insect pest damage in storage and a good alternative to synthetic insecticides in the control of insect pest of stored products.
In Africa, Prostephanus truncatus is a destructive pest of economic importance which has assumed a serious pest status on stored maize and dry cassava chips. This study investigates the effect of processing methods of cassava varieties Manihot esculenta on the proximate composition before and after exposure to P. truncatus. The four cassava varieties used for this study were; TMS 0505, TME 419, NR 8082 and TMS 0581 subjected to two processing method parboiling and plain sun-drying at temperature 28-34oC and relative humidity of 65-75%. The experiment was carried out in a Complete Randomized Design. Proximate composition was carried out to determine the Moisture, Ash, Crude fibre, Fat, Crude Protein and Carbohydrate of the different samples. Analysis of Variance was used for the statistical analysis of the data obtained. The result reveals that the proximate composition of the sundried chips are significant at P<0.05%. All the proximate contents of the sample were significant at P<0.05% before the introduction of P. trucatus. After the introduction of P. truncatus and the storage period of 30days, the sundried sample had a higher reduction in the moisture contents of TMS 0505 with 13.05±0.00a and carbohydrate contents of NR 8082 with 50.0±0.00a. The activity of P. truncatus also has a negative impact on some of the nutritional components of cassava chips.
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