Population dynamics of Prostephanus truncatus (Horn) and Sitophilus zeamais motschulsky in a traditional barn: the influence of maize variety and season

The effects of three maize varieties and two storage seasons on the population dynamics of Prostephanus truncates (Horn) and Sitophilus zeamais Motschulsky were observed in the traditional `Ewe' barn in 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 significantly influenced P. truncatus density (p < 0.05) during the storage period. 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 maximum densities of 131.1, 43.7, and 16.9 adults per kg grain for Abutia, Abeleehi and Dzolokpuita, respectively. S. zeamais density, 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 affect P. truncatus density, but it influenced S. zeamais dynamics and weight loss levels. (Journal of the Ghana Science Association: 2001 3(3): 62-69