The susceptibility of some newly introduced maize varieties in Ghana to to maize weevil Sitophilus Zeamais Motschulsky (Coleoptera:Curculionidae)

Abstract

The susceptibility to infestation of 14 newly introduced improved and 4 local varieties to Ghana to Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) was investigated using shelled grains using the Susceptibility Index (SI). The varieties were: Dobidi, Aburotia, La Posta, Hi-Lysine, Dorke SR, Safita 2, Golden Crystal, Okomasa, Mexico 8049, Composite 4, Kawanzie, Pool 16SR EV85, Pool 16 SR, Gandajika, Ho Local, Kwadaso Local and Pokoase Local. The mean separation of varieties by SI showed a wide array of groupings, indicating that diverse genetic backgrounds could be responsible for susceptibility or resistance. Grains of the majority of the improved varieties could be grouped as resistant. The most susceptible groups contained two of the local varieties. Among the factors that are likely to influence the susceptibility to S. zeamais infestation, prolonged storage of kernels, damage to grain pericarp,addition of germinated grains and nutritional levels (except iron) did not (P>0.05) change their susceptibility. However, addition of flour or mouldy grains significantly (P<0.05) increased susceptibility of grains. An attempt was made to relate S. zeamais susceptibilities on whole grain with those of Tribolium castaneum on milled flour of the same variety so as to determine, the effectiveness and/or advantages of maize storage as whole grain or milled flour. It was found that clear differences exist in the susceptibility or resistance of maize grains or flour to S. zeamais or T. castaneum. The results of the study were to help advise maize breeders in Ghana to incorporate those advantageous characteristics that confer resistance into high yielding commercial varieties for storage as grain or milled flour,and also help, advise small-scale farmers about those varieties that are more resistant for long term storage without the use of chemical protectants