Abstract

Post-harvest losses of maize due to storage insect pest such as the maize weevil, have been recognized as an increasingly important problem in the world. A study was conducted with the objectives to determine the performance of Sitophilus zeamais populations originating from the five Brazilian regions in five varieties of maize and to correlate these variables with the enzymatic activity of insects and nutritional components of the grain. The grain of maize hybrids 30F53H, 30K64H, 30F35H, DKB390 and “crioulo” (not commercial) maize produced in the microregion of Alto Médio Gurguéia in Piauí, was infested with 25 unsexed insects of S. zeamais coming from Bom Jesus, PI; Canarana, MT; Volta Redonda, RJ; Cacoal, RO; and Palmeira das Missões, RS. At the end of 120 days enzyme assays of amylase, lipase and protease from the insects, as well as nutritional analyses of the maize grains were performed. The hybrid with the greatest mass of grain consumption was 30F53H, and insects fed on this achieved the highest growth, followed by 30K64H, DKB390, 30F35H and the “crioulo” with the lowest loss of grain mass and hence the least insect growth. For the data of mass consumed by S. zeamais, the populations of Bom Jesus and Canarana were the ones that ate the most and Palmeira das Missões had the lowest consumption. The population from Bom Jesus, PI was the one that consumed the most grain mass, due to its adaptation to maize from the region. The “crioulo” maize was the one that presented the best indicators of resistance to attack by S. zeamais.

Key words: Digestive enzymes, maize weevil, host plant resistance to insects, stored grain.