273 Research Article Received: 11 March 2010 Revised: 5 August 2010 Accepted: 2 September 2010 Published online in Wiley Online Library: 14 October 2010 (wileyonlinelibrary.com) DOI 10.1002/jsfa.4181 Insecticidal and repellency activity of essential oil of Eucalyptus sp. against Sitophilus zeamais Motschulsky (Coleoptera, Curculionidae) Altemir J Mossi, a Viviane Astolfi, a Gabriela Kubiak, a Lindomar Lerin, a Camila Zanella, a Geciane Toniazzo, a D´ ebora de Oliveira, a Helen Treichel, a* Ivano A Devilla, b Rogerio Cansian a and Rosane Restello a Abstract BACKGROUND: The objective of this work was to evaluate the insecticidal and repellent effect of essential oils of Eucalyptus dunnii, E. saligna, E. benthamii, E. globulus and E. viminalis in the control of Sitophilus zeamais in maize grains. RESULTS: The essential oils chemical composition showed that the E. benthamii presents the cis-ocimene (56.88%) as major compound. Results permitted us to verify that the evaluated species presented different insecticidal action under Sitophilus zeamais. About 100% of mortality was achieved with doses of 65, 100 and 400 μL for E. dunnii, E. saligna and E. benthamii, respectively. After regression analysis the LD 50 values were calculated and E. dunnii was shown to be the most efficient (25.03 μL), followed by E. saligna (37.93 μL) and E. benthamii (121.09 μL). Using the previously calculated LD 50 values, the repellency activity was calculated, allowing us to conclude that all species presented significant values in terms of this important parameter. CONCLUSION: The essential oil of Eucalyptus sp. presented insecticidal and repellency against Sitophilus zeamais Motschulsky (Coleoptera, Curculionidae). Although from an economic point of view synthetic chemicals are still more frequently used as repellents, natural products (essential oils) have the potential to provide efficient and safer repellents for humans and the environment. c  2010 Society of Chemical Industry Keywords: essential oil; repellency activity; insecticidal activity; contact toxicity; Zea mays INTRODUCTION Worldwide, pests (especially weeds, pathogens and insects) are the highest competitor of agricultural crops, drastically reducing the production in the range of 25 – 50%. 1,2 Among the most important pests, weeds alone are responsible for nearly 34% of reduction in crop yield. 2 In order to protect agricultural crops, high amounts of synthetic pesticides are used around the world. Nowadays, the maize weevil, Sitophilus zeamais – Motsch 1855, is the most relevant pest found during storage of maize grains. Aromatic plants and their essential oils have been used in flavors and fragrances, as condiments or spices, in medicines, as antimicrobial/insecticidal agents, and to repel insects or protect stored products. 3–6 In this sense, these oils can represent effective alternatives to synthetic pesticides without producing adverse effects on the environment. 7,8 Among several aromatic plants, the genus Eucalyptus (fam- ily Myrtaceae), represented by over 700 species distributed throughout the world, 9 is one of the most extensively cultivated pulpwoods. 10 Eucalyptus oil has been known for hundreds of years as having antibacterial, antifungical and antiseptic properties. 9 Ac- tive ingredients of commercial available insect repellents include botanicals and citronella. Recently, the US Environmental Protec- tion Agency’s registered insect repellent ingredients approved for application to the skin have included citronella and lemon eucalyptus oils. 11 The pesticidal activity of eucalyptus oils has been related to the presence of components such as 1,8-cineole, citronellal, citronellol, citronellyl acetate, p-cymene, eucamalol, limonene, linalool, α-pinene, γ -terpinene, α-terpineol, alloocimene and aromadendrene. 12 Among the various components of eucalyptus oil, 1,8-cineole is the most important and, in fact, a characteristic compound of the genus Eucalyptus, being largely responsible for a variety of pesticide properties. 13 Eucalyptus essential oils have a wide spectrum of biological activity against fungi, bacteria, insects, mites and weeds and provide a simple, inexpensive and environmentally friendly (non- polluting and less or no toxicological concerns) alternative to pest ∗ Correspondence to: Helen Treichel, Universidade Regional Integrada do Alto Uruguai e das Miss˜ oes – Campus de Erechim, Av. Sete de Setembro, 1621, 99700-000, Erechim, RS, Brazil. E-mail: helen@uricer.edu.br a Universidade Regional Integrada do Alto Uruguai e das Miss˜ oes – Campus de Erechim, Av. Sete de Setembro, 1621, 99700-000, Erechim, RS, Brazil b Universidade Estadual de Goias, BR 153, Km 98, Goias, Brazil J Sci Food Agric 2011; 91: 273–277 www.soci.org c  2010 Society of Chemical Industry