COMPARATIVE EFFICACY OF BOTANICAL EXTRACTS AGAINST STORAGE WEEVILS OF MAIZE (Zea mays L)
Seeds of two maize varieties (Suwan-1-SRY and TZPBSR) were initially evaluated for seed moisture content, germination and Seedling Vigour Index. 50g cleaned, undamaged, uninfested seeds from each seed lot were treated with different botanical extracts from five plant materials (Neem leaf powder, Ocimum leaf powder, Chromolaena leaf powder, Tithonia leaf powder and Piper guineense ground powder) and actellic liquid to give six treatments and one control at recommended dosages. Artificial infestation was carried out with five pairs of newly emerged unsexed adults of Sitophilus zeamais for 14 days after which they were removed. The jars covered with wire mesh and held with rubber bands arranged in a completely randomised design in the laboratory for 12 weeks using three replications. Data were collected on initial and final seed sample weight, number of emerged adults, total number of adult mortality, number of damaged and undamaged seeds and total number of holes per sample. Seeds in storage were also tested for seed viability and vigour. Data collected were subjected to analysis of variance (ANOVA). The initial germination test showed a significant difference between the two maize varieties. All the plant products applied to maize grains significantly reduced weight loss in the grain when exposed to S. zeamais. The plant products tested in this study were also significantly effective on the adult maize weevils. The chemically treated samples and the plant products recorded more as against the non-treated sample. Suwan-1-SRY had the least % weight loss. In terms of plant extracts’ effect on seed germination and seedling vigour, basil was most effective; followed by Chromolaena, actellic, Piper, Tithonia and neem. Results thus indicated efficacy of the various plant products and spices as grain protectants in storage pest management. Botanical pesticides thus represent an important potential for integrated pest management programmes in developing countries.
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