Comparative effectiveness of the powders of some underutilised botanicals for the control of Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)
Biological activities of eight plant powderswere assessedon Callosobruchusmaculatus(F) under prevailing atmospheric condition (28±20C, 70-75 RH.) in the laboratory.The tested plants are Piptadeniastrumafricanum (rootbark), Piptadeniastrumafricanum (leaf), Piper guineense, Aristolochiarepens, Alstoniaboonei, Xylopiaaethiopica, Garcinia kolaand Picralimanitida (Fabricius). They were tested at four treatment levels of 0.5, 1.0, 1.5 and 2.0g of plant powders per 20g of cowpea seeds corresponding to 2.5, 5.0, 7.5 and 10.0% w/w. Percentage beetle mortality was scored at 24, 48, 72 and 96h after treatment. The results obtained showed that powder of P. guineense was the most toxic to C. maculatus evoking 100% mortality at day four with treatment levels of 5.0, 7.5 and 10.0 %w/w respectively. The plant powders of P. africanum (rootbark), P. africanum(leaf) and A. repens evoked 85.00%, 85.50% and 80.00% mortality at day four with treatment level of 10.00% w/w. The least toxic powders on the insect were those of A. boonei, X. aethiopica, G.kola and P. nitida. In a further evaluation of the effects of plant powders on the fecundity and adult emergence of C. maculatus, it was observed that these were drastically reduced in all the treatments except G. kola and A. boonei.
