Toxicity and repellency of essential oils against rice weevil Sitophilus oryzae (L.)

Contact, fumigant, persistence toxicities and repellant activity of three plant essential oils viz., cinnamon (Cinnamomum verum J. Presl), eucalyptus (Eucalyptus obliqua L'Her) and orange oil (Citrus sinensis L.) against rice weevil, Sitophilus oryzae L. were evaluated under laboratory condition. Chemical profiling of tested essential oils through GC-MS studies showed presence of various chemical constituents wherein, eugenol (82.68%), eucalyptol (64.80%) and D-limonene (83.35%) were the major component of cinnamon, eucalyptus and orange oils, respectively. Contact toxicity results indicated that at 120 hours after treatment (HAT), eucalyptus oil caused significantly maximum mortality (100%) of S. oryzae when treated with 0.75 μl/cm2 concentration in comparison to fumigant toxicity (83%) at 2 μl/500 cm3 concentration. The present study demonstrated that among the treated oils, eucalyptus oil has higher contact, fumigant and repellent toxicity and hence it can be harnessed for integrated management of S. oryzae under storage condition.