Potential insecticidal activity of four essential oils against the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae)

Oils extracted from Cymbopogon citratus, Lantana camara, Artemisia camphorata, and Imperata cylindrica plants were used as potential insecticides against the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae). The phytochemical composition of isolated oils was identified by gas chromatograph-mass spectrometry (GC-MS). Oil contact toxicities evaluated adults S. oryzae. activities acetylcholinesterase (AChE), alkaline phosphatase (ALP), transaminases enzymes (AST) measured. L. camara oil (LC50 = 9.81 mg/cm2) demonstrated highest effect, followed C. citratus 10.89 mg/cm2), A. camphorata EO 16.12 I. (LC50= 36.85 inhibition percentages AChE 38.8, 41.7, 35.0, 27.2%; ALP 42.4, 49.3, 28.1, 18.7%; AST 33.9, 38.7, 20.8, 11.8%; ALT 22.7, 30.5, 14.6, 9.6% after treated with cylindrica, respectively. abundant compounds in geranial (25.95%), nerylacetal (8.85%), neral (8.45%), caryophyllene (12.2%), 3-elemene (8.89%), germacrene D-4-ol (20.83%), borneol (19.47%), 5-phenylundecane (10.68%), 6-phenyldodecane (8.70%).