Antifeedant and larvicidal activities of leaf essential oils from Hyptis suaveolens (L.) Poit., Chromolaena odorata (L.) R.M. King and Lantana camara L. against Spodoptera litura Fab. (Lepidoptera: Noctuidae)

The current study was carried out to evaluate antifeedant and insecticidal activities of three essential oils from leaves of Hyptis suaveolens, Chromolaena odorata and Lantana camara against fourth instar larvae of Spodoptera litura under the laboratory conditions. Results indicated that the essential oil from leaves of Hyptis suaveolens had a strong antifeedant impact on the larvae with antifeedant index (AI) of 75.4, 88.5 and 92.9 when leaf disks of Ipomoea batatas were treated with the essential oil at concentration of 1.5, 2.0 and 2.5 %, respectively. Also dose dependent mortalities were observed in the larvae topical treated with the essential oil at different concentrations. At the treated concentration of 0.4 mg per each larva, 68.3 % of the larvae were killed after 24 hours, and 25.0 % were died at the pupal stage after 30 days of observation. At the concentration of 1.2 mg/larva, 93.3 % of the larvae were killed after 24 hours, and no emergence of adults was recorded after 30 days of observation. Larvicidal activity of the H. suaveolens essential oil (with the lethal doses LD50=0.16 and LD95=1.52 mg/larva) was stronger than those of the C. odorata and L. camara essential oils (with LD50=0.57–0.63 and LD95=4.64–4.97 mg/larva) after 24 hour of treatment. GC–MS analysis indicates that the major volatile components of the essential oil from leaves of H. suaveolens are composed of b-caryophyllene (30.0 %), eucalyptol (12.0 %), copaene (5.9 %), and a-bergamotene (5.7 %). This essential oil needs to be further investigated and used as a bio-insecticide for control of S. litura.