Comparative Performance of Pyrethrum [Chrysanthemum cinerariifolium Treviranus (Vis.)] Extract and Cypermethrin on Some Field Insect Pests of Groundnut (Arachis hypogaea L.) in Southeastern Nigeria

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 Research Farm, School of Agriculture and Agricultural Technology, Federal University of Technology, Owerri, southeastern Nigeria, from March to November, 2012. The experiment was laid out in a 2 x 4 factorial arrangement fitted into a Randomized Complete Block Design replicated three times. Groundnut seed variety, ICGV-IS 96894 (ICRISAT) was subjected to germination test to ensure viability. Seeds were planted at a spacing of 30 cm x 15 cm (220,000 plants/ha) on 24 (1 m2) beds with 1 m between furrows. Pyrethrum was extracted through a simple replicable procedure and tested at four rates (0.00, 0.25, 0.50, 0.75 g/100 ml of water). Cypermethrin 10 EC was tested at 0.00, 0.50, 1.00 and1.50 ml/100 ml of water. Insecticides application, pest sampling and leaf damage assessments were carried out at 4, 6 and 8 weeks after planting (WAP). Yield measurement parameters (seed weight, shell weights and pod density) were assessed. Major arthropod pests identified were; Macrotermes bellicosus Smeathman, Peridontopygespp., Helotrichia serrata Fabricius, and Oedaleus nigeriensis Uvarov. Cypermethrin and pyrethrum applications reduced pest incidence (3.25, 2.50, 2.10 insects) and (4.09, 3.62, 3.42 insects), respectively, when compared with unsprayed plots (6.35, 6.16, 6.20 insects) at 4, 6 and 8 WAP. Insecticide type had no significant effect on the population of majority of sampled pests. Sprayed plots had less damaged leaves - 2.80 (cypermethrin) and 2.83 (pyrethrum) as against 4.52 leaves in unsprayed plots at 8 WAP. Sprayed plots also had increased fresh pod weight (0.61, 0.52 kg in cypermethrin and pyrethrum sprayed plots, respectively) as against 0.14 kg in unsprayed plots. Seed weights (0.26, 0.22 kg in cypermethrin and pymethrum sprayed plots, respectively) were significantly distinct from the control (0.06 kg).There were no significant differences (P = .05) in the dry pod or shell weights based on insecticide types. The efficacy of the insecticides was dose related as higher rates gave better performances. Pyrethrum compared favourably with cypermethrin in controlling the field insect pests of groundnut and could serve as alternative to synthetic pesticides in the management of these pests in southeastern Nigeria.