Abstract:
The effects of three maize varieties and two storage seasons on the population dynamics of Prostephanus truncatus and Sitophilus zeamais were observed in the traditional4Ewe’ barn on the field. Two local varieties, Dzolokpuita and Abutia and an improved variety, Abeleehi, were stored with the husk on, during the long season, and Abutia only during the short season, of the 1994/1995 storage period. Destructive sampling techniques were applied to obtain data at monthly intervals for eight months. Maize variety showed significance (P<0.05) on P. truncatus density in the first four months of the long season but was barely so during the late storage phase. However, it did not influence the population dynamics of S. zeamais. Trend analysis showed significant increase in densities of P. truncatus over time especially during the late phase of the long season with a maximum densities of 131.1, 43.7, and 16.9 adults per kg.
T grain for Abutia , Abeleehi and Dzolokpuita, respectively. S. zeamais however peaked at between 280 and 350 adults per kg grain on all varieties after only three months of storage, then stabilized at about 250 insects per kg. grain for the rest of the season. Maize variety also influenced weight loss with Dzolokpuita faring better. Good husk cover and relatively harder grains of Dzolokpuita may explain the lower P. truncatus density and weight loss recorded for this variety. Season did not to affect P. truncatus density but it influenced S. zeamais dynamics, and weight loss levels. The relative economic value loss also increased with time with value loss of 21.1%, 21.5%. and 19.4% for Abutia, Abeleehi and Dzolokpuita, respectively after eight months of storage
