Hanshika Singh, Shyam Gupta
Growing concern about the environmental and health risks associated with synthetic pesticides has increased interest in plant-based pesticides for controlling stored-grain pests. This study evaluated the efficacy of an ethanolic leaf extract of Ocimum kilimandscharicum against the rice weevil, Sitophilus oryzae, a major pest of stored wheat. Wheat grains were treated with different concentrations of the ethanolic extract (20%, 30%, 40%, and 50% v/v), and mortality was recorded at 1, 3, 7, 14, and 21 days. The experiment was conducted with three replicates, and an untreated group was maintained as the control. Mortality increased progressively with extract concentration and exposure time, with the highest mortality (57.78%) observed at 50% concentration after 21 days. One-way analysis of variance followed by Tukey’s post hoc test showed significant differences among treatments during the later observation periods (p < 0.05). The bioefficacy of the ethanolic leaf extract was also assessed by measuring grain weight loss caused by S. oryzae infestation. The extract exhibited dose- and time-dependent insecticidal activity and correspondingly increased grain protection. These findings indicate that O. kilimandscharicum has promising insecticidal properties and may offer an environmentally compatible option for managing stored-grain insect pests.