Chemical characterization and insecticidal effect of Moringa oleifera L. seeds extracts on common bean weevil (Acanthoscelides obtectus Say)

Some insects cause high losses of the common bean during storage, namely, Acanthoscelides obtectus Say. Chemical insecticides are commonly used to control insects, but their overuse adversely affects the environment and consumers' health. There is, therefore, the need for an alternative control method. This study was aimed to evaluate the chemical characterization and insecticidal property of Moringa oleifera seed extract on the developmental stages of A. obtectus in stored beans. Three types of M. oleifera seed extracts, namely methanol, ethanol and acetone extracts, were used at doses of 12.5, 25 and 50 µl/ml each. HPLC-MS was used to characterize these extracts. The toxicity of extracts against the adults, the number of eggs and the viability rate of laid or emerged eggs of A. obtectus were evaluated. The results show that M. oleifera seed extract is rich in Hesperidin, Quinic acid, gallic acid, protocatechuic acid, 4-OH benzoic acid, cynaroside, isoquercitrin, cosmosiin, quercitrin, luteolin, naringenin, salicylic acid, Apigenin and Fumaric acid. The acetone extract, from day 2, showed a 100% mortality rate in all doses compared to about only 14% in the control treatment. The number of eggs laid in control (236.67) was higher than the null (0) in acetone treatment at 50 µl/ml. M. oleifera seed extracts contain chemical molecules. They significantly reduced the damage caused by A. obtectus on stored P. vulgaris grains. Therefore, they can be used as an alternative to chemicals for the protection of stored foodstuffs.