Bioactivity of Two Plant Derived Essential Oils Against the Rice Weevils Sitophilus oryzae (L.) (Coleoptera: Curculionidae)

The uncontrolled use of synthetic chemicals is a great hazard for the environment and consumers. In the present study, essential oils from two different plants were extracted using hydro-distillation. These oils were also assayed for their insecticidal properties against rice weevil Sitophilus oryzae. The results showed that the essential oils of Syzygium aromaticum and Aegle marmelos had fumigant toxicity against S. oryzae. During fumigation, toxicity bioassay and percentage mortality increased with increasing concentration. The toxicity of 10 days old adults of S. oryzae increased with concentration from 15 to 30/100 mu l, with exposure time 24-48 h. The LC50 of S. oryzae adults against S. aromaticum and A. marmelos were 15.347 and 16.133 mu l at 48 h exposure, respectively. These investigations showed that the essential oils can be used as alternative grain-protectant for stored-grain insect pests.