Galls of Guiera senegalensis J.F. GMEL (Combretaceae) as potential source of insecticides against the main cowpea pest Callosobruchus maculatus (Fab.) (Coleoptera: Bruchidae) detoxification enzymes

Abstract

The cowpea weevil, Callosobruchus maculatus (F.), is a major pest of cowpea (Vigna unguiculata (L.) Walp.) in storage. A laboratory study was conducted to investigate the inhibition potential of Guiera senegalensis galls on C. maculatus detoxification enzymes. Methanol extract from galls of G. senegalensis exhibited strong inhibitory effects of the activity of C. maculatus acetylcholinesterase (AChE) and mixed-functional oxidase enzymes. The chemical composition of the extracted oils was examined by gas chromatograph (GC)-flame ionisation detectors (FID) and mass spectrometry. Twelve components were identified, namely 2-Hydroxy-4-methoxybenzophenone, n-Pentadecane, Octadecane, 1,2-Benzenedicarboxylic acid, dibutyl ester, Palmitic Acid, Hexadecane, Cis-vaccenic acid, Oleyl alcohol, stenol, n-Eicosane, n-Heneicosane and vincubine. This plant could be used for improving the efficacy to various insecticide classes against C. maculatus and as an alternative to synthetic insecticides.

Keywords: Callosobruchus maculatus, enzymatic detoxification system, galls, Guiera senegalensis