Abstract
This study was aimed at controlling cowpea bruchid (Callosobruchus maculatus L. Walp) in storage using selected plant products, specifically, the best combination of the plant products for cowpea storage was determined. Plant materials such as Moringa seeds, cashew nut seeds, Bush mint leaves and Hot pepper were sourced in and around the Northeast region and were used in treatments for cowpea storage. 5kg of cowpea grains were randomly allotted to seven (7) treatments in a Completely Randomized Design (CRD), replicated three times. The data obtained were subjected to Analysis of Variance (ANOVA). Means were separated using Duncan Multiple Range Test (DMRT) at 5% level of significance. Non-inferential statistics such as Frequency tables, means and percentages were also used. Results after the period of storage revealed that some treatments had an increase in weight while some showed significant losses. There was increased (p<0.05) weight for cowpeas treated with bush mint and hot pepper BM+HP (0.50 g) compared to the control while that of cashew seed oil and moringa seed oil CS+MS (1.47 g) revealed a significant loss (p<0.05) after storage compared to the control. It was further observed that the control showed the least (p<0.05) number of live and dead insects (C. maculatus) followed by BM+HP (2.33 and 9.00, respectively) compared to the other treatments. A higher (p<0.05) value was observed in BM (251.33) for number of dead insects. It was further observed that the control showed the least (p<0.05) number of live and dead insects (C. maculatus) followed by BM+HP (2.33 and 9.00, respectively) compared to the other treatments. While the highest number of live insects recorded was similar (p>0.05) between BM (55.00) and cashew seed oil (CSO) (59.67) compared to the control. A higher (p<0.05) value was observed in BM compared to the control giving the highest rate of dead insects (251.33a ). This might be attributed to the presence of carvone which is usually extracted from bush mint and used commercially to kill insects. It was concluded that treatment of cowpeas in storage with BM+HP can significantly reduce insect population, grain damage and post-harvest loss of stored cowpea. Furthermore, cowpeas treated with HP only were observed to give the same result as BM+HP (clean grains with very negligible insect effect) although the colour turned to red. It is thus recommended that BM only, HP only or a combination BM+HP be used as most effective control measures (next to PICs) for cowpea storage in Northeastern Nigeria.