Larvicidal Activities of Cold-Pressed Essential Oils Extracted from three Lamiaceae Species against the Stored-Product Pest, Plodia interpunctella (Hübner, 1813) (Lepidoptera: Pyralidae)

The larvicidal activities of cold-pressed essential oils of extracted from three Lamiaceae species, Menta piperita, Origanum onites and Lavandula officinalis were evaluated against the stored-product pest, Plodia interpunctella. Larvicidal activity bioassays of three essential oils against Plodia interpunctella at three different concentrations (20 µL/mL, 30 µL/mL and 50 µL/mL) were carried out under the laboratory condition at 25±1°C temperature, 60±5% relative humidity and 14:10 (L:D) photoperiod conditions. As the concentration of essential oils increased, the mean number of larvae of Plodia interpunctella decreased but mortality rate increased. At 20µL/mL concentration, the essential oil of Lavandula officinalis was the most effective, whereas Mentha piperita was the least effective against the larvae of Plodia interpunctella. At 30µL/mL concentration, the essential oil of Mentha piperita was the most effective, whereas Lavandula officinalis was the least effective. At 50µL/mL concentration, the essential oil of Lavandula officinalis was the most effective, whereas Mentha piperita was the least effective. When 100% mortality of the essential oil of Lavandula officinalis was obtained after 4 days at 50µL/mL concentration, that of Origanum onites was obtained after 5 days at 50µL/mL concentration. Essential oil of Mentha piperita showed less insecticidal effect against Plodia interpunctella larvae compared to both Lavandula officinalis and Origanum onites. When the concentration and the exposure times of each essential oil against Plodia interpuntella larvae increased, the efficiency of essential oils and percent mortality increased at all essential oils. 50µL/mL concentration of essential oils extracted from Lavandula officinalis and Origanum onites can be used and effective during 4 days against Plodia interpunctella in storages.