Insecticidal contact toxicity of several essential oils against stored product pests

Results of laboratory bioassays in Petri dishes on evaluation of contact toxicity of Illicium verum, Artemisia absinthium and Abies sibirica essential oils (EOs) against larvae of khapra beetle, Trogoderma granarium Ev., adults of grain weevil, Sitophilus granarius L., and rice weevil, Sitophilus oryzae L., and confused flour beetle, Tribolium confusum Duv., and larvae and adults of the lesser mealworm, Tenebrio molitor L., are presented. EOs commercial samples from retail pharmacy were tested at doses 0.01, 0.25, 0.50, 0.75 and 1.00 µl/cm2. A treated Petri dish surface treted with acetone was used as a control. The experiment was carried out in triplicate. Mortality of insects was assessed after 1, 3, 6 and 24 hours post exposure. After exposure insects were placed into untreated Petri dishes for 3 days. The main components of the A. absinthium EOs are thujil alcohol (19.65%), phellandrene (16.71%), borneol (12.1%) and thujone (11.55%) was found. The major component of I. verum EOs was anethole (98.64%). Isobornyl acetate (57.25%), a-pinene (13.55%) and limonene (10.62%) were found as the main components of A. sibirica EOs.i> S. oryzae an S. granarius were most sensitive to each EO. I. verum EOs was the most effective and caused 100% mortality of each insect at the dose 0.25 µl/cm2.