COMPARATIVE EFFICACY OF Piper guineense (SCHUM AND THONN) AND PIRIMIPHOS METHYL ON Sitophilus zeamais (MOTSCH.)

Powdered seeds of black pepper Piper guineense Schum and Thonn applied at 0.1, 0.2, 0.3, and 0.4g/50g of maize grains were evaluated for maize weevil, Sitophilus zeamais control. An insecticide treatment (1g pirimiphos methyl/50g grain) and an untreated control were included. The effect of particle sizes of the seed powder from P. guineense was also evaluated. Percentage weevil mortality was recorded at 3, 5, 7, 14 and 21 days after infestation. At 5 days post-treatment, all rates of seed powder caused significantly higher mortality than the control while the synthetic insecticide recorded 100 % mortality. The finer particle sizes (1mm, 600µm) of the pepper seed powder compared favourably with pirimiphos methyl in the control of S. zeamais. Grains treated with the powder showed significant reduction in the number of progeny derived from surviving S. zeamais. There was no observable feeding damage on grains treated with the higher concentrations and finer particle sizes. The results provide a scientific rationale for the use of P. guineense in post-harvest protection