author(s)
Dessenbe Théophile, Nukenine Elias N and Mbaïlao Mbaiguinam

abstract
Plants extracted substances can constitute the best alternative to synthetic chemical insecticides and a good preservation of the environment because they are biodegradables. The leaves of Plectranthus glandulosus were extracted with hexane, acetone and methanol, then fractionated and tested on adults of Sitophilus zeamais and Callosobruchus maculatus. Corn and cowpea seeds were each administered three (3) different doses (1, 5 and 10 g/kg) of these extracts to assess adult mortality of S. zeamais and C. maculatus. The other percentage of mortality obtained was collected and analyzed. In all cases, the hexane fraction was more effective than that of acetone and methanol because it induced more mortality and it appears that S. zeamais is more vulnerable than C. maculatus to the different extracts. The hexane extracts induced mortality of 98.08% against adults of S. zeamais and 70.00% against adults of C. maculatus in one day of exposure with the dose of 10g/Kg. P. glandulosus extracts can be used as a natural solution against insect plant damage.