Comparative efficacy of seven plant products on the cowpea burchid, Callosobruchus maculatus F. development and damage

An experiment was conducted to investigate the insecticidal activities of seven plant materials (1-5g/100g cowpea seeds) namely: citrus peel powder (CPP), Acacia leaf powder (ALP), Occimum leaf powder (OLP), mahogany bark powder (MBP), hot pepper powder (HPP), ginger powder (GP) and mahogany wood ash (MWA) and a synthetic insecticide, pirimiphos-methyl dust (PMD) (0.1-0.5g/100g cowpea seeds) as standard. The experiment was laid out in a completely randomized design, replicated three times. Results showed that MWA was superior at all rates of application in reducing cowpea seed weight loss and seed damage. The effectiveness of the treatments in succession was MWA> PMD> GP> HPP>MBP>OLP>ALP>CPP. The most effective rate of application was 5g/100g cowpea seeds, rather than by 2-3g/ 100g cowpea seeds. There was no significant difference among treatments and the untreated control in the germinability of cowpea seeds, although the lowest germination was recorded in cowpea seeds treated with 1g HPP. Similarly, when the seeds treated with plant materials were cooked, they did not leave any flavour strong enough to influence acceptability by the consumers.