Efficacy of Olive oil, Groundnut oil, Soybean oil and Palm kernel oil in the Control of Callosobruchus maculatus (F.) in Stored Cowpea (Vigna unguiculata L. Walp)

Abstract

Laboratory experiments were conducted to investigate the potentials of four different vegetable oils (olive oil, groundnut oil, soybean oil and palm kernel oil) for the protection of stored cowpea against Callosobruchus maculatus. Ife-brown seeds (a susceptible variety) used for the experiment were subjected to the different oil treatments applied at 0.2 ml per 50 g of seeds. The experiment was laid out in a completely randomised design with three replicates per treatment.
All the oils tested suppressed the development of C. maculatus to some extent with groundnut oil and palm kernel oil exhibiting similar results in the control of the pest. There was no significant difference between palm kernel oil and groundnut oil for adult mortality, larvae and pupae emergence at P< 0.05 but it was significantly different for the F₁ progeny emergence. Palm kernel oil was more effective against the F₁ progeny emergence. These two oils could be used in the storage of cowpea against C. maculatus.

Keywords: Olive oil, Soybean oil, groundnut oil, palm kernel oil and Callosobruchus maculatus