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Callosobruchus maculatus is the most damaging insect pest of stored cowpea (Vigna unguiculata) seeds in Nigeria. Thus, this present research work was put in place to assess the insecticidal activities of the extracts obtained from the leaf and stem bark of Kigelia africana (Lam.) Benth against the cowpea seed beetle, C. maculatus. The parameters that were assessed were adult mortality, oviposition and adult emergence of C. maculatus. The experiments were conducted under laboratory conditions of 28AE2 C temperature and 75 AE 5% relative humidity. The extracts were applied at dosages of 0.3, 0.6, 0.9 and 1.2 mL per 20 g of cowpea seeds. The two extracts of K. africana were found to be toxic to the survival of the C. maculatus. However, the extract obtained from the leaf was more potent to the beetle than the extract obtained from the stem bark of the same plant. The two extracts also reduced ovipositipon and completely suppressed adult emergence at the highest dose of 1.2 mL per 50 g of cowpea seeds. The results obtained in the present research work showed that the two extracts of K. africana were effective in suppressing the population of the infamous stored pest of cowpea seed beetle, C. maculatus and could therefore be recommended to replace the harmful synthetic chemical insecticides in protecting cowpea seeds in storage.

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The pulse beetles, Callosobruchus maculatus is a principal field-to store pest of cowpea in the tropics and at present synthetic insecticides constitute a major means of control. The insecticidal effect of ethanolic extracts and powders of Momordica charantia leaf against the cowpea beetle, Callosobruchus maculatus Fab. were carried out in the laboratory. The efficacy of powder and ethanolic extract of M. charantia leaf as toxicants against C. maculatus were investigated using contact toxicity and oviposition deterrence. The powders and extracts were applied at various dosages of 0.2, 0.4, 0.6, and 0.8 g and 0.2, 0.4, 0.6 and 0.8 ml per 20 g of cowpea seeds. Beetle mortality was monitored for 96 h. The mortality of the insect increased with increase in dosage and period of exposure. Within 24 h post treatment, 0.8 g dosage of the plant powder recorded the highest beetle mortality of 35% but its effect was not significantly (p>0.05) different from that of 0.4 and 0.6 ml. At 96 h of post-treatment, all the dosages of the plant powders recorded above 75% insect mortality with 0.8 g of the powder achieving the highest insect mortality of 85% and its effect was not significantly (p<0.05) different from 0.2, 0.4 and 0.6 g. At 96 h post treatment, 0.8 ml of the extract achieved the highest mortality of 95% which was not significantly (p<0.05) different from that of 0.6 ml. All dosages of the extract recorded up to 80% bruchid mortality within 96 h post treatment. At all treatment levels, insect mortality was significantly (p<0.05) different from the control. It was observed that oviposition was reduced in both powder and extract treatments when compared to the control. The results show that both powder and extract of M. charantia were effective in controlling C. maculatus and could serve as alternative to over-dependence on synthetic insecticide for preservation of stored cowpea seeds against C. maculatus.