The Efficacy of Atemisia annua and Occimum grastissimum Leaf Powders against Callosobruchus maculatus (F) (Coleoptera: Bruchidae) on Stored Vigna unguiculata

Abstract: Labouratory trials were carried out to test the efficacy of Atemisia annua and Occimum grastissimum leaf powders against the cowpea bruchid (Callosobruchus maculatus) on stored Vigna unguiculata seeds. The efficacy of the plant powders on the adult emergence rate was investigated in two separate sets A and B. From the results obtained, it was observed that both plant powders posses' insecticidal properties. 100% mortality was observed after eight days of subjecting the adult bruchid to the plant powders. They were effective against the insect evidenced from the reduced rate of emergence and percentage number of seeds with perforations. Significant differences were obtained between the control and treatments. The highest numbers of emerging adults recorded in the control experiment were 397.00 ±147.08 and 605.00±121.62. The highest number recorded for A. annua and O. grastissimum in the four weeks were 85.50±21.92 and 60.00±4.24. A reduction in the population of an insect in most instances makes for reduced pest impact on stored products. This was evidenced in this research as percentages of perforated seeds in the control, A. annua and O. grastissimum treated seeds were 80%, 57% and 27.5% respectively. These results show that A. annua and O. grastissimum have potential as botanicals for preventing the loss accrued to this insect.