Acta Scientifica Malaysia (ASM)

Callosobruchus maculatus, is an undisputedly major insect pest militating against legume food grains availability and security. This experiment was conceived to evaluate the toxicity effect of some spice powder (Capsicum annum and Piper guineense) in the control of cowpea beetle (C. maculatus) on stored cowpea seeds arranged in a completely randomized design (CRD) with four treatments: 5g of dried Capsicum annum fruit, 5g of Piper guineense leaves, 5g of Piper guineense seeds and the control (no treatment) and replicated five times. The spice powders were assessed using the following parameters: percentage mortality of adult weevils at 24, 48, and 72 hours, progeny emergence after 35 days of storage, percentage weight loss, percentage of damaged grains and percentage germinability of treated and untreated cowpea seeds. The results obtained showed that at 72 hours, C. annum fruit had the highest mortality (50%), followed by P. guineense seed powder (45%) and was significantly more potent than P. guineense leaves (25%) and the untreated control (2%), respectively. The percentage of adult emergence in untreated cowpea seeds was 40.9%. While C. annum fruit powders and P. guineense seed powders completely inhibited adult emergence. C. annum fruit powder provides significant highest protection of the treated grains, followed by P. guineense seeds compared to the untreated seeds. The plant powders did not adversely affect seed germinability, suggesting that seeds treated with P. guineense seeds and C. annum can be used as an alternative to chemical pesticides against C. maculatus infestation and suppression of seed damage by smallholder farmers. Further study, recommended to evaluate the powders shelf life to determine if additional application is required after a specific amount of time to maintain the powder efficacy.