PHYTOCHEMICAL CONSTITUENTS AND INSECTICIDAL EFFICACY OF THE ROOT AND LEAF POWDERS OF MIMOSA DIPLOTRICHA AND ASPILIA AFRICANA AGAINST CALLOSOBRUCHUS MACULATUS (FAB.) (COLEOPTERA: CHRYSOMELIDAE)

ABSTRACT The increased and persistent usage of synthesized insecticides and pesticides in the control of pests has created a lot of ecological as well as environmental challenges hence, the divergence into the increasing use of botanical insecticides. However, there exist little or no empirical evidence on the use of Aspilia africana and Mimosa diplotricha in insect pest control. This study, therefore, demonstrates the efficacy of the root and leaf powders of A. africana and M. diplotricha against the cowpea beetle, Callosobruchus maculatus. The beetle were exposed to grains treated with one of four treatments (plant powders: 0.5, 1.0, 1.5 and 2.0g) of the two plants at different exposure period of 24, 48, 72 and 96 hours, and data realized were used in calculating the percentage mortality. Both exhibited a high level of mortality which was a function of treatment concentration and of exposure time. At 96 hours of exposure with treatment concentration of 2g, percentage mortality caused by root and leaf powders of A. africana was 70% and 54%, respectively. The root and leaf powders of M. diplotricha, however, resulted in 52% and 50% mortality on similar conditions (at 96 hours). Although powders from all four treatment types exhibited insecticidal activities by causing varying levels of mortality to C. maculatus, the highest death rate was caused by the root treatment from A. africana after a 96 hours exposure. The high insecticidal activity demonstrated by the root powders suggests that they hold more potential in the control of C. maculatus compared to the leaf powders, however, more studies is needed to elucidate a better method of harnessing the insecticidal properties of A africana and M. diplotricha.