The powders and oils extracts of Anacardium occidentale (L.) seeds and Allium sativum (L.) bulbs were tested as contact insecticides against the cowpea bruchid, Callosobruchus maculatus (Fab.) in cowpea seeds. The powders were incorporated at rates 1, 2.5 and 5/20g of cowpea seeds and acetone extracts of the plants were also applied at 0.5, 1 and 1.5ml per 20g of cowpea seeds to assess contact mortality of adult insect, oviposition, adult emergence and damage assessment. The results obtained showed that at 72 hours; 1, 2.5 and 5/20g of cowpea seeds evoked 63.3, 80 and 100% adult mortality of the cowpea bruchid while the corresponding results for A. sativum were 60.7, 73.3 and 100% mortality respectively. All concentration of acetone extracts that were used evoked 100% mortality of C. maculatus after 72 hours of post treatment. Complete protection of seeds and complete inhibition of adult emergence in both powders and extracts of A. occidentale and A. sativum were achieved. The results obtained from this research revealed that powders and extracts of A. occidentale seeds and A. sativum bulbs were effective in controlling cowpea bruchid, C. maculatus in stored cowpea seeds.

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The bioactivity of Alstonia boonei De Wild (Apocyanaceae) against Callosobruchus maculatus (Fab.) (Coleoptera: Chrysomelidae) in stored cowpea seeds was evaluated in the laboratory by admixing leaf, stem bark and root powders of A. boonei with cowpea seeds at ambient temperature of 28+2⁰C and 70+5% relative humidity. The powders were incorporated into 20g of cowpea seeds, Vigna unguiculata at 0.0% (control) 2.5%, 5.0%, 12.5% and 25.0% (w/w) concentration. The ability of the plant powders to protect cowpea seeds was assessed in terms of mortality rates after 24 - 96 hours post treatment, oviposition and adult emergence, percentage weight loss and damage after the first filial generation (F₁). All the tested plant part powders significantly (P<0.05) reduce the longevity of adult C. maculatus on treated cowpea seeds. From the study, the plant powders could be ranked in order of effectiveness thus; stem bark > leaf > root. Alstonia boonei can be used as biopesticide against C. maculatus and its incorporation into traditional storage pest management is strongly recommended.

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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