Comparative effectiveness of the powders of some underutilized botanicals for the control of Callosobruchus maculatus (Fab.) (Coleoptera : Bruchidae)

Abstract

Biological activities of eight plant powders including Piptadeniastrum africanum (rootbark), Piptadeniastrum africanum (leaf), Piper guineense, Aristolochia repens, Alstonia boneei, Xylopia aethiopica, Garcinia kola and Picralima nitida were assessed under prevailing atmospheric condition (28±2⁰C, 70-75 r.h.) in laboratory on Callosobruchus maculatus (Fabricius) 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 plant powders on survival and development of C. maculatus, it was observed that fecundity and adult emergence were drastically reduced in all the treatments except G. kola and A. boonei

Key words: Plant powders, Callosobruchus maculatus, fecundity and adult emergence