Insecticidal and repellent activities of Cymbopogon citratus (Poaceae) essential oil and its terpenoids (citral and geranyl acetate) against Ulomoides dermestoides



• The lethal and sublethal effects of lemongrass essential oil and their constituents were tested on the peanut beetle, Ulomoides dermestoides.
• The chemical analyses revealed 13 constituents to lemongrass essential oil being citral and geranyl acetate the main constituents in this essential oil.
• Lemongrass oil, citral, and geranyl acetate were toxic and reduce the survivorship of U. dermestoides at different doses.
• Lemongrass essential oil and their constituents exhibited significant effect to reduce the respiration rate and altering the locomotor activity.
• Lemongrass essential oil, citral, and geranyl acetate may represent valuable source of green insecticides to U. dermestoides.



The peanut beetle, Ulomoides dermestoides Fairmaire (Coleoptera: Tenebrionidae), is a worldwide pest of stored grains. This study evaluated the toxicity and repellency of lemongrass (Cymbopogon citratus) essential oil and its components (citral and geranyl acetate) against U. dermestoides adults. Lethal doses (LD50 and LD90), survival rate, respiration rate, and repellent activity were determined. The major components of lemongrass essential oil were neral (24.6%), citral (18.7%), geranyl acetate (12.4%), geranial (12.3%), and limonene (7.5%). Lemongrass essential oil (LD50 = 5.17 μg insect−1), citral (LD50 = 4.17 μg insect−1), and geranyl acetate (LD50 = 7.21 μg insect−1) caused high contact toxicity in U. dermestoides adults. The survival rate was 99% in control insects, decreasing to 65.7% in insects exposed to the LD50 of lemongrass essential oil, 41.3% in insects treated with geranyl acetate, and 28.5% in those treated with citral. Insects exposed to lemongrass essential oil, geranyl acetate, or citral showed low respiration rates, reduced locomotor activity, and avoidance responses to treated surfaces. These findings demonstrate that lemongrass essential oil and its terpenoid components exhibit insecticidal and repellent activity against U. dermestoides, suggesting their potential for controlling this stored grain pest.


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