Determination of impact of Azadirachta indica L. leaves on adults and eggs of Callosobruchus maculatus Fabricius, the largest predator of stored cowpea (Vigna unguiculata Walp) by an applicable method by farmers

Abstract

The effect of neem leaves has been tested in the laboratory on eggs and adults of cowpea weevil (C. maculatus). Different formulations of this plant were applied to these forms of C. maculatus Fab. Grinding fresh contact sheets induced significant lethal effects from 96.12% to 100% on eggs; whereas 100% of mortality was recorded at the end of eight days of applica-tion to three adults with higher doses. Fumigation on turn proved less effec-tive than contact on eggs. It induced a maximal effect of 95.73% mortality with the larger dose (D4: 0.02912g/cm3). On adults, we recorded highest mortality (100%) from the 7th day of the show with the highest dose. The aqueous extract of neem leaf powder was less effective than all other formu-lations on the eggs as well as adults of this insect; with a higher mortality rate (74.99%) observed on the eggs with the application of the concentration C2. On adults we recorded a maximum effect (100% mortality) from the 13th day of the application with the highest concentration (C1). These mortalities would be related to the support of several active molecules contained in neem as established in literature.