Efficacy of Eucheuma denticulatum Extract and Azadirachta indica Powder against Maize Weevil (Sitophilus zeamais) Infesting Stored Maize Grains

Abstract

Storage insect pests destroy food grains in storage. In the present study, the insecticidal activity of red seaweed extract (Eucheuma denticulatum) and neem (Azadirachta indica) was examined against maize weevils (Sitophilus zeamais) and the quality of the stored maize was assessed for a three months storage period. Three rates (0.0, 1.6 and 4.8% w/w) of neem powder and seaweed extract were used as treatments. The collected data were subjected to analysis of variance (ANOVA) using General Linear Model in SPSS computer software packages (version 25) and mean comparisons were conducted using Turkey’s (HSD) test at the 5% level of significance. Sitophilus zeamais, mortality, grain weight loss, and rate of germination were recorded for each treatment. The 4.8%w/w mixture of seaweed extract and neem seed powder was more toxic, followed by the mixture of the extract and neem leaf powder (84.5% and 73.3% mortality rates, respectively), while in the control, mortality was 20%. In all treatments, Sitophilus zeamais mortality increased with increasing doses. Grain weight loss was high in the control (5.6%), followed by grains treated with 1.6% extracts of Eucheuma denticulatum alone (2.8%). The percentage of damaged maize grains was high in the control (14%) and low in grains treated with 4.8% seaweed extract and neem leaf powder (3.3%). Percentage germination was high in grains treated with 4.8% and 1.6% seaweed extracts alone (96% and 87% respectively) and in control (91%). Additionally, sensory evaluation results in terms of color, odor and overall acceptability showed that maize grains treated with both botanicals could be accepted by the general public for consumption. The results indicate promising potential for seaweed extract and neem powder in controlling maize weevils, offering sustainable and environmentally friendly solutions for stored grain protection.