Protectability of nine Nigerian medicinal plants against cowpea beetle,Callosobruchus maculatus (Fab.) (Coleoptera: Bruchiidae) in storage

A study was conducted to examine the protectability of nine Nigerian medicinal plants against Callosobruchus maculatus at an ambient temperature of 28?±?2?°C and relative humidity of 70?±?5%. The nine plants used were dried and milled into fine powder before application. Among the nine plant powders used, Zanthoxylum zanthoxyloides effected highest mortality rate of 73.40 and 100% at 5% (wt/wt) concentration within two and three days of application, respectively. The effect of this plant at this level of concentration was significantly (p?<?0.05) different from other plants. However, all the plant powders effected high mortality rate as they all achieved more than 50% beetle mortality within four days of application at 20% (wt/wt) concentration. Only the powder of Z. zanthoxyloides at 10% (wt/wt) concentration was able to achieve 0% adult emergence, 0% seed damage and 100% damage reduction. Moreover, powder of Z. zanthoxyloides, Aristolochia ringens and Colocasia esculenta at 20% (wt/wt) was also able to prevent the emergence of adult C. maculatus, prevent seed damage and achieve 100% damage reduction. All the powders had low weevil perforation index when compared to the control which had above 50% weevil perforation index. At all levels of concentration, the effect of the powders was significantly (p?<?0.05) different from the control. However, Z. xanthoxyloides appeared to be the most effective; therefore, the effective utilisation of Z. xanthoxyloides as a botanical pesticide could minimise the use of hazardous chemicals in stored product pest control since it is of a botanical source.