Optimum Insecticide Doses Determination of Seed Oil of Three Botanicals Jatropha Curcas L., Helianthus Annus L. and Cocos Nucifera L. against Maize Weevil Sitophilus Zeamais Mots.

The insecticidal effect of four dosage rates of three botanicals namely Jatropha curcas, Heliathus annus and Cocos nucifera was tested on the maize weevil Sitophilus zeamais Mots.. This is done for the purpose of finding a replacement for conventional insecticides which has been found to be harmful to man. The seed oil was applied topically at the rate of 0.1, 0.2, 0.3 and 0.4 mL per insect. There were a total of 20 insects per Petri-dish. There were four replicates per treatment. Insect mortality was recorded on 12 hourly basis for 48 hours. The results of insects treated with all dosage rates of C. nucifera showed a significantly higher mortality when compared with the control. In the case ofH. annus, insect mortality ranged from 40-100, 70-100, 60-100 and 80-100% and for J. curcas the result ranged from 0.0-100, 40-100, 80-100 and 80-100% for rates of 0.1, 0.2, 0.3 and 0.4 mL, respectively, from 12 hrs to 48 hrs post application. The control experiment remained at 0% level throughout the period of the experiments.