Oviposition Deterrent and Egg Hatchability Suppression of Secamone afzelii (Schult) K. Schum Leaf Extract on Callosobruchus maculatus (Fabricius) (Coleoptera: Chrysomelidae)

The efficacy of oil extracted from the leaves of Secamone afzelii was evaluated in the laboratory against Callosobruchus maculatus infesting stored cowpea. Leaf extracts from S. afzelii were obtained through the soxhlet extraction method using methanol and hexane as the solvent. Each of the extracts was tested by exposing five pairs of adult beetles to various levels of 0.5, 1.0, 1.5 and 2.0 ml corresponding to 2.5, 5.0, 7.5 and 10.0% v/w concentrations admixed with 20g cowpea in three replications respectively, in a Completely Randomized Design (CRD). Control treatment was set along. The results showed that oviposition and percentage egg hatched were significantly (P 0.05) suppressed on seeds treated with higher treatment level of extracts. Leaf extract with hexane at 2 ml (10.0% v/w)/20g cowpea seeds was most effective in suppressing oviposition and egg hatched. Therefore, S. afzelii exhibit promising degree of oviposition deterrent and ovicidal properties and, thus, have a great potential for use as a plant-based biopesticide as an alternative to synthetic insecticides for controlling C. maculatus infestation on stored cowpea grains.