EFFECTS OF INITIAL INFESTATION ON THE DEVELOPMENT OF Callosobruchus maculatus(Fab.) and Sitophilus zeamais Motsch. IN STORED COWPEA AND MAIZE

The aim of the study was to determine the influence of varying levels of Callosobruchus maculatus (F.) and Sitophilus zeamais Motsch. infestation on survival and development of the insects in stored cowpea and maize seeds respectively. Three levels of infestation (1, 2 or 3 pairs) of the insects` species each were used to infest 100 g of the commodities. The data from the storage experiment were collected using a total number of 12 experimental units arranged in completely randomized design (CRD) for each test insect. Counts of adult mortality of the insects, number of eggs laid, progeny emergence and percentage weight loss of the stored seeds were recorded after keen observation and examination. Based on the results, there was significant difference (P < 0.05) in the number of adult insects that died in the cowpea and maize seeds infested with 2 and 3 pairs of C. maculatus and S. zeamais compared to non - infested seeds. Significant differences were also recorded in the number of eggs laid by the insects, number of emerged adults and seed weight loss in the levels of infestation and the non - infested control. Results showed that levels of infestation exposed the seeds to the destructive activities of stored product insect pests under prevailing ambient conditions. It is therefore suggested that environmental hygiene and appropriate storage devices that could prevent cross infestation are necessary to sustain national food security.