Activities of Organic Extracts of Cassia occidentalis Leaves on the Mortality and Fecundity of Callosobruchus maculatus (Main Insect Pest of Vigna unguiculata Seed Stocks)

Callosobruchus maculatus Fab (Coleoptera: Chrysomelidae) is the most formidable pest of cowpea (Vigna unguiculata) in the field. The damage continues even in stocks intended for food. The present work was carried out to evaluate the insecticidal effect of organic leaf extracts of Cassia occidentalis on mortality and emergence of F1 progeny in storage. The extracts were tested in contact in 90 mm diameter petri dishes with different doses. Phytochemical screening was carried out using coloring and precipitation tests. Mortality of C. maculatus was assessed between 1 and 17 days after infestation. The data were processed according to the General Linear Model procedure and using Minitab 19 software. The results of the statistical analysis showed that the methanolic extract gives a better mortality rate on Callosobruchus maculatus. These results are corroborated by phytochemical tests with the identification of molecules (alkaloids, flavonoids, tannins, polyphenols, etc.) likely to be responsible for this insecticidal activity.