Sustainable Grain Protection: Combatting Rice Weevils (Sitophilus oryzae) with Natural Plant Powders

Abstract

Grain storage plays a pivotal role in ensuring food security and sustaining agriculture for future generations. However, a wide array of insect pests, including the rice weevil (Sitophilus oryzae), pose a significant threat to stored grains. This study was conducted at the Laboratory of the Department of Seed Science and Technology, Bangladesh Agricultural University, Mymensingh, from October 2019 to March 2020, to evaluate the efficacy of plant-based powders for managing rice weevils. The experiment was designed using a Completely Randomized Design (CRD) with three replications and seven treatments. These treatments included five botanical powders—Ocimum tenuiflorum (Tulsi), Azadirachta indica (Neem), Polygonum hydropiper (Biskatali), Nicotiana tabacum (Tobacco), and Lantana camara (Lantana)—applied at three dosage levels: 1 g, 3 g, and 5 g per 100 g of grain. Additionally, a chemical insecticide (Sevin 85 SP @ 0.25%) and an untreated control were included for comparison. Results revealed that neem leaf powder was the most effective, achieving the highest adult insect mortality and the lowest adult emergence. In contrast, Lantana powder exhibited the least efficacy, allowing 94.38% more adult insects to emerge compared to neem powder. Untreated grains experienced a 20% weight loss due to rice weevil infestation after one month of storage, whereas treatment with 5% neem leaf powder reduced weight loss to a mere 0.14%. This reduction was statistically significant compared to all  other treatments. These findings suggest that neem leaf powder at 5% is a highly effective, eco-friendly, and safe alternative to chemical insecticides for controlling rice weevils in stored grains.