Chemical composition and insecticidal effects of essential oil from Citrus aurantium L. leaves on three major stored products pests

In order to replace pesticides with less hazardous compounds, plant essential oils are widely investigated. In this study, the effects of essential oil of Citrus aurantium L. leaves was tested for fumigant, contact and repellent effects against adults of Rhyzopertha dominica, Tribolium castaneum and Oryzaephilus surinamensis. The experiments were conducted in completely randomized design with 5 replications in 27±2oC, 65±5% R.H. and dark condition. The essential oil were extracted using Clevenger-type apparatus and analyzed by GC-MS. Fumigant toxicity was studied in 50 mL containers and contact toxicity experiments were performed using petri-dish method and five different concentrations and the mortality was investigated after 24 h. Repellency of the oils was studied using the choice bioassay system in petri-dish with five concentrations, at 2 and 4 h exposure times. Analysis of chemical composition showed high amounts of monoterpenes in essential oil, mainly linalool (32.41 %). Probit analysis showed that the LC50 of C. aurantium essential oil against O. surinamensis was 262.93 µL/L air but there was no fumigant toxicity against R. dominica and O. surinamensis. Results of contact toxicity showed that C. aurantium had more toxicity for R. dominica (LC50=0.13 µl/cm2) and O. surinamensis (LC50=0.11 µl/cm2) than T. castaneum (LC50=1.84µL/cm2). Percent repellency (PR) increased with increasing exposure time and concentration of the essential oils. After 2h exposure time the PR of C. aurantium oil was 48, 90 and 84 % at the highest concentration of essential oil (1.194×10-1 µL/cm2) for R. dominica, T. castaneum and O. surinamensis.