Efficacy of three botanical powders and their combination against Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) in maize grain storage
摘要
Sitophilus zeamais Motschulsky infestation causes severe post-harvest losses of grains in Ghana leading to a major reduction in the quality and economic value. The combined efficacy of three botanical powders against adult S. zeamais was assessed. The botanical powders of Aframomum melegueta, Pipper nigrum, and Zingiber officinale in unmixed and admixed forms and Fossil Shield® 9.0 as a control were evaluated against the adult Sitophilus zeamais in stored maize grains at different dosage rates. The botanical powders in admixed and unmixed forms were used to treat 100 g of maize grains infested with 40 adult S. zeamais at dosage rates of 0 g, 10 g, 20 g, and 30 g. The treatments were kept in glass jars covered with muslin cloth and kept at a constant temperature of 26 ± 2 °C and relative humidity RH of 70 ± 5% with a photoperiod of (L: D) 12: 12 h for 28 days. The experiment was laid out in a completely randomized design. The highest mean adult mortality was recorded from admixed alligator pepper + black pepper at 20 g and 30 g at day 21, followed by the admixed alligator pepper + black pepper at 30 g at day 28. The lowest mean maize grain damage in the admixed botanicals was recorded from alligator pepper + black pepper at 30 g exposure at day 28. From the results, we found that the admixed powders demonstrated anti-feedant properties. The study found effectiveness between the admixed botanical powders in affecting adult S. zeamais mortality and the prevention of grain damage. Their effectiveness in affecting adult S. zeamais mortality and maize grain damage is dose dependent. Farmers could apply the botanical powders in admixed forms to exert stronger efficacy against S. zeamais.