FUMIGATION TOXICITY OF ESSENTIAL OILS AGAINST Rhyzopertha dominica (F.) IN STORED MAIZE GRAIN

The Rhyzopertha dominica F. (Coleoptera: Bostrichidae) is a primary pest of stored grains in many regions of the world. In this work we evaluated the fumigant activity of essential oils of Ocimum basilicum L., Citrus aurantium L., Mentha spicata L. and Croton pulegiodorus Baill on adult R. dominica in stored maize. Tests were conducted to determine lethals concentrations (CL50 and CL100) and mortality (fumigation). The fumigation test was done in containers made of glass containing 10 individuals of R. dominica, where essential oils were applied at different concentrations: O. basilicum and M. spicata (5, 10, 15, 20, 30 and 40 mu L/L of air), C. aurantium (10, 20, 30, 40, 50 and 60 mu L/L of air) and C. pulegiodorus (0, 20, 30, 50, 70 and 90 mu L/L of air). After 48 hours of exposure to the oils the percentage of insect mortality was evaluated. According to LC50 and LC100 the toxicity of essential oils decreased in the following order: O. basilicum>M. spicata>C. pulegiodorus>C. aurantium. The essential oil of O. basilicum exhibited strong fumigant toxicity against R. dominica adults, with a LC50 value of 17.67 mu L/L air and LC100 value of 27.15 mu L/L air. The C. aurantium essential oil required higher concentrations than O. basilicum, M. spicata and C. pulegiodorus to kill insects. However, all oils evaluated presented fumigating property to promote the control of R. dominica and demonstrated potential use in the management of this coleoptera.