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Studies were carried out in the laboratory to determine the efficacy of powders from plant parts of Ricinodendron heudelotii against the storage pests Sitophilus zeamais and Callosobruchus maculatus on stored maize and cowpea, respectively. Leaf, bark and root powders were added as admixtures to 100 g of grains to assess contact toxicity, damage assessment, progeny production and grain germination. Results indicated that the plant materials were toxic to the two insect species with over 30% and 75% mortality for S. zeamais and C. maculatus, respectively. Observable damage level was significantly (p ≤ 0.05) lower in treated grains while progeny production by both insect species was significantly (p ≤ 0.05) reduced. Grain germination of both crops was not affected by the powders. The potential use of P. heudelotii in storage pest management is discussed.
Neem (Azadirachta indica A. Juss.) seed oil (NSO) is acclaimed to have some form of insecticidal action against more than 400 insect species in at least 10 to 13 orders. The main delimitating factor in the wide acceptance of this well tested plant as a storage pest bioinsecticide is its foul sulfurous smell and bitter taste which impinges on the acceptability and marketability of treated produce. To ameliorate this shortfall, therefore, an assessment of the potential of impregnating different storage materials; [plastic containers (PLC), Bagco bags (BCB), Black polyethylene bags (BPB), white polyethylene bags (WPB) and calico bags (CAB)], with NSO in the management of Callosobruchus maculatus (F.) in stored Bambara seeds (Vigna subterranea L.), was conducted in the laboratory. The experiment was laid out in a 4 x 5 factorial arrangement fitted into a completely randomized design (CRD). Factor A represented four concentrations of NSO (0.00, 0.50, 1.00, 1.50 ml/ 100g seed), while factor B were the five different storage materials. The treatments were replicated four times Generally, seeds stored with impregnated storage materials recorded more bruchids mortality, reduced oviposition rate, decreased number of emerged insects (F1 and F2) and had less damaged seeds (and hence decreased weevil perforation index, WPI) than the control. Concentration performance was dose related though the highest (1.50 %) did not differ statistically (P=0.05) from the medium (1.00 %) concentration. Seeds stored in BPBs had the highest mortalities, but recorded the lowest in number of eggs oviposited, egg/seed ratio, F1, F2 and cumulative emergence, respectively. These results differed significantly (P=0.05) with the seeds stored in other materials. BPB stored seeds were also the least damaged with lowest exit holes/seed, seeds with holes and WPI, respectively. The performance of BPB was closely followed by seeds stored in WPBs in all the parameters tested. Conversely, seeds stored in BCBs recorded the lowest mortalities but the highest in all other parameters assessed. Other storage materials (PLC and CAB) had better storage quality than BCB materials. Impregnation of storage materials with NSO could be a better option to direct seed application with its attendant drawback. The use of NSO impregnated black polyethylene bags, within the scope of the storage materials screened, to control damage by C. maculatus in stored Bambara seeds, should be encouraged.
The efficacy of different formulations of the Citrullus colocynthis active ingredients in powder or emulsifiable concentrate in cowpea stored in different storage sacks (damour, polyethylene, gunny plastic and jute) protection against Callosobruchus maculatus attack was evaluated. All the formulations used were effective bioinsecticides against C. maculatus. They secured considerable protection for the stored seeds for different periods, depending on the kind of storage sacks and the kind and the formulation rate used. Damour and polyethylene sacks proved to be highly suitable for storage of cowpea seeds treated with different formulations. They completely protected the seeds from infestation for seven months in the majority of formulations. No infestation appeared during seven months and hence no weight loss was detected in the stored seeds. Gunny plastic and jute sacks protected the seeds for shorter periods. They were considered to be less suitable for storing the treated cowpea seeds. The weight loss detected depended on the storage method and the rate of formulation used. All the tested formulations significantly reduced the number of eggs laid in comparison to control. Powdered formulation of alcohol and chloroform extracts of C. colocynthis, applied at the doses of 8 and 16 g/kg of seeds and 16 g/kg, respectively, were superior in comparison to other formulations used, as the oviposition deterrent index (ODI) was 100%. Moreover, no adult C. maculatus was recorded during seven months of storage when damour sacks for storing cowpea seeds treated with alcohol or chloroform extract powder formulations were used. Different formulations used had no adverse effect on seeds’ germination.
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