SUSCEPTIBILITY OF STORED QUALITY PROTEIN MAIZE VARIETIES TO SITOPHILUS ZEAMAIS MOTSCH. (COLEOPTERA: CURCULIONIDAE): ASSESSMENT OF HARDNESS AND PROTEIN CONTENTS

Effects of Sitophilus zeamais (Motsch.) infestation on protein contents was evaluated on ten maize varieties, comprising nine Quality Protein Maize (QPM) varieties and one non-QPM which served as a check. One hundred grammes of each maize variety were infested with ten pairs of newly emerged S. zeamais in separate Kilner jars. The protein contents of the maize varieties were measured before and after S. zeamais infestation to determine the amount of losses incurred as a result of feeding by S. zeamais. The result showed that at 45 days after infestation with S. zeamais, FLINT-Q was the most susceptible variety with the highest mean number of F1 progeny (24.63) while SAMMAZ 17 (12.63) had the least amongst the QPM varieties. At 90 days after S. zeamais infestation, DENT-Q (51.63) had the highest mean number of F2 progeny whereas SAMMAZ 17 (19.25) had the least. Maximum losses in albumin/globulin proteins were observed in DENT-Q (59.68 %) which decreased from an initial value of 0.62 % to 0.25 %. The maximum reduction in the amount of zein protein was observed in DENT-Q (55.36 %) which decreased from an initial value of 0.56 % to 0.25 %. The greatest reduction in glutelin protein was in the variety SAMMAZ 19 (59.26 %) which decreased drastically from 0.81 % to 0.33 % after 12 weeks of storage. Minimum reductions in zein (22.22 %) and glutelin (43.85 %) proteins amongst the QPM varieties were observed in SAMMAZ 17. The results of test of grain hardness showed that SAMMAZ 17 appeared to be relatively harder than all the other QPM varieties. It can therefore be concluded that SAMMAZ 17 with relatively hard kernel is the most tolerant variety to S. zeamais infestation which can be stored for 90 days with minimum insect infestation and reduction in protein contents. Keywords: Sitophilus zeamais, Protein Contents, Stored Quality Protein Maize Varieties