Entomocidal properties of Christmas bush, Alchornea cordifolia (Schum & Thorn) bark powder against maize weevil, Sitophilus zeamais motschulsky (Coleoptera: Curcilionidae) in storage

The maize weevil (Sitophilus zeamais) is a very destructive pest of maize. Synthetic chemicals have mainly been used extensively to control this pests and this has led to serious health and environmental problems. The present study investigated the entomocidal properties of bark powders of Alchornea cordifolia against Sitophilus zeamais on stored maize in the Integrated Science Education Department laboratory of the University of Education, Winneba, Central Region, Ghana, at a temperature of 30±2̊C and 75±5% relative humidity. Bark powders was added as admixtures to 20.0 g of grains at the following rates of 1g, 2g, and 3g to assess contact toxicity, damage assessment, progeny production, repellency and seed germination ability. Results indicated that the plant material was toxic to the insect (P<0.05). The bark powder of A. cordifolia applied at 3g greatly induced the highest mortality of 95% after 21 days, repelled almost 92% of the weevils, significantly inhibited adult emergence and seed damaged by the weevils up to about 97% and 98.6% respectively compared to other concentrations (P<0.05). The bark powder also had no effect on germination. The present study revealed that A. cordifolia bark powder can be used as good alternatives to chemical insecticides against S. zeamais and its incorporation into traditional storage pest management and integrated pest management is strongly recommended in developing countries.