Determination of the efficacy of rice husk biochar as biopesticide against Sitophilus zeamais

Maize weevils (Sitophilus zeamais) are a significant pest of stored maize in Africa, causing substantial damage to its physical, nutritional, and economic value and rendering it unsuitable for replanting. This study, conducted at the Demonstration Farm of the Agricultural Technology Department of Federal Polytechnic, Ile-Oluji, Nigeria, investigated the efficacy of Rice Husk Biochar (RHB) as a biopesticide against this pest. Three concentrations of RHB (15 g, 10 g, and 5 g) were tested against Sitophilus zeamais infesting stored maize, using a Completely Randomized Design (CRD) with three replicates. The dependent variables measured after treating infested maize with the RHB were the Susceptibility Index (SI), Mortality Rate (MR), Grain Weight Loss (GWL), and Germination Percentage (GP) of the stored maize. Results indicated that RHB significantly influenced all dependent variables. The SI reached its highest value (56 %) at the lowest concentration (5 g) of RHB compared to 36 % at 15 g. MR was highest (84 %) at 15 g of RHB compared to other concentration levels. GWL was lowest at higher RHB concentrations, showing only a 4 % loss at 15 g compared to a 9 % loss in the control group for the same weight of RHB. GP was highest (98 %) at RHB (15 g) Analysis of variance showed significant effects across all dependent variables at a p-value ≤ 0.05. Rice Husk Biochar demonstrates potential as a biopesticide for managing Sitophilus zeamais, offering a sustainable and environmentally friendly alternative to synthetic pesticides.