Fumigant Toxicity of Methyl Benzoate Loaded onto Different Carrier Materials Against the Rice Weevil, Sitophilus oryzae

Abstract

Methyl benzoate is a naturally occurring botanical compound that has insecticidal activity against a broad spectrum of insects and provides a potential alternative to synthetic insecticides. In this study, we evaluated the fumigant effectiveness of methyl benzoate (MB) loaded onto three simple carrier materials including filter paper disc, cotton disc and charcoal tablet against adults of the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) with and without wheat grains. Also, the effects on germination and quality of stored wheat grains have been investigated. The results showed that after 12 h, MB-filter paper disc was the most effective treatment against S. oryzae. However, within 48 h MB-cotton disc achieved the highest activity both in the presence and absence of wheat grains. Throughout the 30 days of storage periods, MBactivated charcoal exhibited the highest activity against S. oryzae compared to other treatments. All MB-tested carrier materials had no negative impact on the germination, carbohydrate, and protein contents of stored wheat grains. These results suggest that using MB loaded onto some carrier materials like activated charcoal may significantly maintain its effectiveness over storage time in the fumigation process. Overall, this study provides good evidence that MB-activated charcoal tablets hold promise as a safe and effective alternative to hazardous synthetic fumigants such as phosphine and methyl bromide for stored product pest control.