Abstract:
Studies were conducted at the Pest Management Laboratory of the Department of Crop, Soil and Pest Management, the Federal University of Technology, Akure, Ondo State, Nigeria to investigate the insecticidal effects of powder and ash from the cob, silk and tassel of maize, rice husk powder and ash for the management of Callosobruchus maculatus (F.) on Oloyin variety of cowpea, Vigna unguiculata L. Walp and of Sitophilus zeamais L. on yellow maize variety. Six levels of the powder and ash, 0.00g, 0.2g, 0.4g, 0.6g, 0.8g and 1.0g per 20g of cowpea and maize seeds were evaluated against Callosoruchus maculatus and Sitophilus zeamais under laboratory conditions of 25-28oC, and 65-75% relative humidity. Mortality of C. maculatus as well as Sitophilus zeamais was assessed at 24hours, 48hours for C.maculatus and 72hours and 96hours for Sitophilus zeamais respectively after treatment application. Data were taken on oviposition, adult emergence and seed weight loss. Results from the study revealed that the percentage mortality increased significantly with concentrations. Highest number of C. maculatus died in seeds treated with 0.6g to 1.0g of the powders of rice husk, tassel and silk of maize with reduced number of eggs and the emerged adults when compared with the control. Similar result was also observed when treated with the ash of the above plant materials at the same higher dosage. Significantly higher weight loss was recorded in the seeds treated with cob powder compared with the seeds treated with tassel, silk and rice husk powder. No mortality of Sitophilus zeamais was recorded when treated with the maize powder and ash of cob, silk and tassel with a significantly higher weight loss from increased oviposition and adults emergence.
