Biopesticidal Potential of Indigenous Plant Extracts against Rice Weevil in Stored Wheat

Stored products are significantly affected by certain well-known stored grain pests, with Sitophilus oryzae L. (Coleoptera: Curculionidae) being one of the most destructive pests of stored products. It is a primary pest that causes substantial quantitative and qualitative losses. The present study was conducted to investigate the insecticidal efficacy of different plant extracts from four commonly grown plants in Pakistan: ginger (Zingiber officinale), neem (Azadirachta indica), clove (Syzygium aromaticum), and tobacco (Nicotiana tabacum) against S. oryzae infesting stored wheat. Crude extracts from these plants were applied to stored wheat at various dose rates (20, 40, 60, 80 mg). Adults of S. oryzae were introduced to the treated wheat and observed for mortality, repellency, and grain damage. The results of the study indicated that the maximum mortality of S. oryzae (99.17%) was recorded due to the application of crude extract of Z. officinale, while the minimum mortality of S. oryzae (67.50%) was recorded due to the crude extract of N. tabacum at an 80 mg dose rate after a 10-day exposure interval. The maximum grain damage due to S. oryzae (0.19%) was observed in N. tabacum treated crude extract at an 80 mg dose rate, while the minimum grain damage due to S. oryzae (0.04%) was observed in Z. officinale treated crude extract at an 80 mg dose rate. Z. officinale also exhibited the maximum repellent effect on S. oryzae (95.77%). This study concluded that Z. officinale emerged as a potent, readily available biopesticide against S. oryzae, surpassing current alternatives with near-eradication efficacy, minimal grain damage, and a proactive repellent effect, paving the way for sustainable and eco-friendly pest management. Further research is needed to optimize extraction methods, dosage recommendations, and assess long-term effects on grain quality and storage stability.