Comparative toxicity of essential oils of Lisea pungens Hemsi and Listea cubeba and blends of their major constituents against Trichoplusia ni (Lepidoptera: Noctuidae)

Abstract: Contact toxicity of essential oils extracted from Lisea pungens Hemsl. and Listea cubeba (Lauraceae) and blends of their major constituents were assessed against third instar Trichoplusia ni larvae through topical application. Both of the oils showed strong activity against T. ni larvae with LD₅₀ values of 87.1 and 112.5 µg/larva respectively. 1,8-Cineole and Carvone from essential oil of L. pungens Hemsl., ã-terpinene, limonene, and p-cymene from essential oil of L. cubeba were the most active against T. ni, and accounted for the major toxicity of the oils. Toxicity of blends of selected constituents indicated a synergistic effect among the active and inactive constituents, with the presence of all constituents necessary for the total toxicity of the natural oils. Our results show that essential oils of L. pungens Hemsl. and L. cubeba have potential for development as commercial insecticides. Key words: cabbage looper, essential oil, Lisea pungens Hemsl. Listea cubeba, 1,8-cineole, carvone, ã-terpinene, limonene, p-cymene, toxicity