Insecticidal activities of indigenous plants from Volta Region, Ghana in managing Sitophilus zeamais and Prostephanus truncatus in stored maize

Abstract. Ankutse DK, Eziah VY, Afreh-Nuamah K. 2021. Insecticidal activities of indigenous plants from Volta Region, Ghana in managing Sitophilus zeamais and Prostephanus truncatus in stored maize. Intl J Trop Drylands 5: 48-60. The rising rate of pest resistance, and the high expense and health risks associated with insecticide use, have become a source of public concern. This study aimed to discover and evaluate plant species used by farmers in the Volta Region to control Sitophilus zeamais (Motschulsky, 1855) and Prostephanus truncatus (Horn, 1878) in stored maize grains. In a survey, Azadirachta indica, Clausena anisata, Phyllanthus amarus, Picralima nitida, Vernonia amygdalina, Nauclea latifolia, and Momordica charantia were discovered to be grain protectants against stored insect pests. All of the plants indicated above were employed in the experiment, except for A. indica, which has a long history of being used to combat grain storage pests. The insecticidal activity of dried powders (5 and 10%) and aqueous extracts (0.1 and 0.2 g/mL) of plants against P. truncatus and S. zeamais was examined. Plant species and dose rate influenced repellency. In the V. amygdalina treatment, plant powders and methanol extracts were the most poisonous to insects. The toxicity of V. amygdalina to P. truncatus and S. zeamais was 83.3 and 86.7%, respectively, at higher concentrations of 0.2 g/mL. At 0.2 g/mL, all plant extracts exhibited a significant difference in Actellic repellent (P0.05); nevertheless, C. anisata had the highest repellent action against P. truncatus and S. zeamais, with 80.0 and 66.7%, respectively. As grains were treated with plant extracts, oviposition and egg emergence were reduced compared to the control. When embryonic stages of insects were treated with methanol extracts of botanicals, the number of adult insects decreased. These findings show that the studied plants have the potential to aid in the development of post-harvest protection technology against the principal pests of stored grains, P. truncatus and S. zeamais. As a result, farmers should use it to control P. truncatus and S. zeamais in stored maize grains.