Essential Oils of Three Hypericum Species from Colombia: Chemical Composition, Insecticidal and Repellent Activity Against Sitophilus zeamais Motsch. (Coleoptera: Curculionidae)

The maize weevil (Sitophilus zeamais) is one of the main insect responsible of significant losses in stored products, and to keep nutritional value of them to find effective and safe solutions are very important. The Hypericum genus might be a potential source of new bio-insecticides due to the chemical composition of essential oils. In this study, components of essential oils of three Hypericum species were investigated for first time by Gas Chromatography-Mass Spectrometry (GC-MS) and, fumigant and contact toxicities as well as the repellent activity of essential oils of them were evaluated against S. zeamais adults. While the main components in H. mexicanum oil were determined as n-nonane (53.08%) and alpha-pinene (25.28%), the major constituents were determined as alpha-pinene (45.52%) and beta-caryophyllene (13.59%) in the essential oil of H. myricariifolium. Chemical composition of essential oil of H. juniperinum were found to be n-nonane (12.0%), alpha-pinene (8.25%), geranyl acetate (7.93%), and beta-caryophyllene (13.60%). The results revealed that H. mexicanum and H. myricariifolium oils have fumigant toxicity (LC50 < 500 mu L/L air) and a potential action as repellents (RP > 70% at 6.2-22.7 mu L/L air) for the control of the pest.