Protecting Cowpea Seeds (Vigna unguiculata) against Cowpea Weevil (Callosobruchus maculatus) with Unripe Banana Peel Liquid

A laboratory study was conducted to determine the protective effects of unripe banana peel liquid extract on cowpea seeds (Vigna unguiculata) against cowpea weevil (Callosobruchus maculatus). Petroleum ether solvent was employed in the extraction process which yielded the extract (23.71% w/w). Four concentrations (10%, 1%, 0.1% and 0.01% w/v) of the liquid extracts were each mixed with 5 g of cowpea seeds put in plastic vials in triplicate. Each experimental unit had ten pairs of adult Callosobruchus maculatus. The effects of different concentrations of each treatment on insect mortality, weight loss and viability of cowpea seeds were assessed. The highest concentration (10% w/w) induced the highest perentage mortality of C. maculatus. There was a significant difference (P<0.05) in perentage mortality of weevils in the treated and untreated cowpea seeds subjected to weevils. Unripe banana peel liquid extract gave appreciably reduced average percentage weight loss when compared to the untreated seeds (control 2). There was a significant level of weight loss between treated and untreated cowpea seeds (P<0.05). Seeds treated with the highest concentration (10% w/w) of liquid extract showed the least weight loss and was not viable whilst those treated with 1% w/w, 0.1% w/w and 0.01% w/w of liquid extracts were viable, with control 2 having the least percentage viability. Seeds treated with liquid extract at concentration 0.01% w/w prevented infestations by weevil’s larvae, and favoured germination more than seeds which were not treated with liquid extract and also not subjected to weevils but kept for the same duration as the experiments (control 1). Unripe banana peel liquid extract protected cowpea seeds from infestations by the weevil’s larvae. Hence, this research supports the local use of unripe banana peel liquid as a protectant and also reveals the concentration of liquid extract which favours germination of cowpea seeds.