Evaluating the effects of indigenous cowpea Weevicallosobruchus Rhodesianus Management methods on stored cowpea..

Abstract

The insecticidal properties of Combretum imberbe ashes, Carica papaya leaf powder, Eucalyptus leaf powder, lonchocarpus capassa leaf powder, and pepper powder were evaluatedto determine the efficacy and optimize their use in reducing cowpea losses to Callosobruchus rhodesicmus. The specific objectives of the study were to: determine the proportion of cowpeaweevil damaged seeds from the various indigenous management methods, evaluate cowpeaweevil fertility and effect on germinability over a three months period. Two cowpea varietiesIT 18 and CBC2 were infested with 10 Callosobruchus rhodesicmus adults and then subjected tothe different indigenous insect management methods. Hundred uninfested seeds of each varietywere placed in mutton bags and replicated three times in a RCBD. The number of oviposited hatched eggs and emergent holes were counted on all the cowpeas seeds under each treatmentfortnightly from one month after infestation. A top paper germinability test was done to the seedsafter three months to assess the level of weevil damage. The results were analysed using Genstat software. There were highly significant differences (PO.OOl) between the treatment methods, varieties and counts. Actellic dust a standard control had 67 eggs which was about ten tunesmore effective than the most effective indigenous method, Combretum imberbe method. The control treatment without any protectant had the greatest number of emergent holes 304.2, which, was 186.8 more than Combretum imberbe which was the most effective indigenous method. Pepper was the second best management method having nine times more holes than Combretum imberbe. Eucalyptus leaf powder was the least effective. There was a strong positive (PO.OOl) correlation (0.81) between number of eggs and holes in the cowpea seeds for the seven methods evaluated. From the three counts made for all the seven methods evaluated the number of eggs was about 5 times the number of emergence holes. There was highly significant difference (PO.OOl) in the method used and variety in terms of percentage germination. Variety IT 18 always had a higher germination percentage irrespective of the method of managementused. Overall, the study observed that protecting stored cowpea using plant products at smallholder level is better than leaving them unprotected hence farmers are recommended to use plant products to protect their grain legumes. Future research is recommended to determine exact concentrations of plant materials that will totally protect the grain legumes from damage by insects.