Management of the maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) using host resistance and other intrinsic factors.

Maize is a staple grain cereal that is consumed worldwide for the supply of daily energy requirements. However, its infestation by the weevil, Sitophilus zeamais often results in both qualitative and quantitative losses, which must be managed effectively. The health hazards that are associated with the application of synthetic insecticides for the management of pest infestations of stored products have necessitated the continual sourcing of safer and affordable alternatives. Hence, a laboratory experiment was conducted to assess the effects of morphological, biophysical and some intrinsic factors in fifteen improved maize varieties on their susceptibility or otherwise resistance to infestation by the maize weevil, S. zeamais. Firstly, the morphological and biophysical characteristics of the maize varieties were determined. Copulating pairs of adult S. zeamais were placed in containers that contained undamaged maize grains for seven days to allow for oviposition, after which the adults were removed. Thereafter, the number of eggs laid and adults that emerged were counted. The susceptibility index of each maize variety was calculated from the data obtained from oviposition and adult emergence. Also, the proximate, elemental, and antinutrient compositions of the maize varieties were determined. There was no significant difference (p > 0.05) in the size and hardness of seeds among the varieties with the size range of 0.78–0.95 cm3 while the hardness ranged from 17.43 N in SAMMAZ-15 F to 19.08 N in SAMMAZ-35. The maize varieties differed significantly with respect to proximate, elemental, and antinutrient compositions. The susceptibility of the seeds to infestations by S. zeamais differed significantly among the varieties and across the generations, with the potential for loss of resistant property during later generations. The data from the susceptibility index revealed that TZL COMP4, TZEE W POP and SAMMAZ-29 were the most resistant to infestations by S. zeamais. Although, several factors could have been responsible for the susceptibility or resistance of maize seed varieties to infestations by S. zeamais, however oviposition hardness and moisture were the most important factors in the present study. [ABSTRACT FROM AUTHOR]