Study to evaluate the insecticidal efficacy of pyrethrum, Chrysanthemum cinerariifolium, relative to a synthetic insecticide (Cypermethrin 10 E. C) in the control of some field pests of groundnut was carried out at the Teaching and
<p>Okra, grown and consumed in every ecological zone, is amongst the most sort after fruit vegetable crops in Nigeria. The crop is often infested by diverse field insect pests, especially the flea beetle <em>Podagrica</em> species, which impinges on its growth and productivity. The application of synthetic pesticides has been the generic insect pest control measure due to its touted effectiveness. These synthetics, however, has safety concerns which include; hazard to human health, amplification of toxins in the food chain, pest resurgence, domestic animals and human poisoning, environmental pollution, insect resistance, natural enemies destruction; springs, wells, rivers, and underground water contamination. Stakeholders are advocating an alternative management approach that is sustainable with less negative social and environmental impact. This study, therefore, compared the insecticidal efficacy of <em>Artemisia annua</em> (source of the antimalarial artemisinin) seed extract in comparison with Cypermethrin 10 EC, a synthetic insecticide, in controlling <em>Podagrica</em> species, the major field insect pests of okra. The trial was set out in a 7 x 4 factorial arrangement integrated into a randomized complete block design and replicated thrice. Cypermethrin 10 E.C was tested at 0.25 ml, 0.50 ml, and 0.70 ml/100 ml of water, while <em>Artemisia annua</em> extract was applied at 1.00 ml, 2.00 ml, and 3.00 ml/100 ml of water respectively. The control for both treatments was designated 0.0 ml. Data on leaf damage and flea beetle abundance were carried out from 4-10 weeks after planting (WAP) whilst the pods’ weight was measured at maturity. The result shows that i) the concentrations of Artemisia extract and Cypermethrin sprayed provided comparable protection to okra against the flea beetle; ii) the yield of okra (pod weight) does not vary between <em>Artemisia annua</em> extract and Cypermethrin treated plots; and iii) flea beetle infestations vary with okra developmental stages.</p>
The cowpea beetle, Callosobruchus maculatus Fab. is an economically important pest of stored grain and causes serious damage to stored peas. The application of pesticides has been the generic control measure due to its effectiveness, affordability and ease of application. However, due to the apparent health and environmental consequences with pesticides, stakeholders are advocating for an alternative management approach that has less social and environmental impact and is more sustainable. Consequently, this study examined the attraction of mated female to volatile blends collected from pods of cowpea plants (Borno-brown and black-eyed cultivars) at three developmental stages developing podsie; 15-17 days after anthesis (daa), fully developed pods (18-20 daa) and mature pods (> 20 daa). The beetles’ responses to the pods’ odour were determined using a two-arm olfactometer, and gas chromatography-mass spectrometry (GC-MS) was used to identify and quantify the volatile compounds collected from the pods. The results showed that female C. maculatus attraction increased with the pod’s age, and that the composition and abundance of volatile compounds varied between cowpea cultivars and the pod’s developmental stage. These findings form an important bases towards developing alternative approach for the management of bruchids. Key words: volatile compounds, cowpea plants, GC-MS, pod’s developmental stage, days after anthesis
Dry seeds of cowpea, an important food, and cash crop to farmers, are heavily infested by Callosobruchus maculatus (Fabricius, 1775) during storage, causing huge economic loss. As a result, farmers spray pesticides on their harvest to control the pest attack with little consideration for the consequences of their actions. Due to health and environmental concerns associated with pesticide applications, farmers, marketers, and end-users are seeking alternative safer routes to handling this infestation problem. Thus, this study investigated the response of mated female C. maculatus to odour cues from different bean types using two-arm and four-arm olfactometers. The volatile organic compounds from the preferred beans (Borno brown and black-eyed beans-cultivars of Vigna unguiculata Walper, 1843 and adzuki bean – Vigna angularis (Willdenow) Ohwi & Ohashi, 1969), were analysed using gas chromatography-mass spectrometry (GCMS) techniques and headspace volatile organic compounds were tested in 2-arm olfactometer with the view to identifying possible attractants or deterrents that could be used in effective control of storage pest. The results indicated that (a) the female C. maculatus responded discriminatorily to odour stimuli from the bean types tested, (b) eighteen volatile compounds were present in the bean types tested and (c) the volatile compounds identified varied in abundance profile. These suggest that host location and selection behaviours by female C. maculatus are moulded by the types and concentrations of the volatile compounds present in the beans.
Neem (Azadirachtaindica 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 managementof 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.
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