The use of essential oils for the control of Callosobruchus subinnotatus (Pic) in stored Vigna subterranea L.

Abstract

Studies were conducted in the Crop Science laboratory, University of Calabar to evaluate the insecticidal actions of essential oils (EOs) of Xylopia aethiopica, Dennetia tripetala, Pysostigma venenosum and Senna hirsuta in the management of Callosobruchus subinnotatus. The EOs were extracted using soxhlet apparatus with n-Hexane as the solvent. Four concentrations (0.25%, 0.50%, 1.00% and 2.00 %) and n-Hexane as control were laid out in completely randomized design with three replications. Parameters assessed included repellency, fumigant action, weight loss as well as Lethal concentration (LC50) of the treatments to the beetles at the lowest concentration of 0.25%. The EO of Senna hirsuta treated samples generally resulted in significantly (P > 0.05) lower weight loss than n-hexane treated samples. LC50 computation revealed that D. tripetala and P. venenosum (LC50 0.22 at 48 hrs) were most efficacious against C. subinnotatus. The result supports the use of the test plants by small scale farmers in the protection of stored V. substerranea against C. subinnotatus.

Keywords

• insecticidal action
• repellency
• contact toxicity
• fumigant action
• lc50
• weight loss