Toxicity of essential oils from plants towards Tyrophagus putrescentiae (Schrank) and Suidasia pontifica Oudemans (Acari: Astigmata) Carla P.O. de Assis a, * , Manoel G.C. Gondim Jr. a , Herbert A.A. de Siqueira a , Cláudio A.G. da Câmara b a Departamento de Agronomia-Entomologia, Universidade Federal Rural de Pernambuco, Av. Dom Manoel de Medeiros, s/n, 52171-900 Recife, Pernambuco, Brazil b Laboratório de Produtos Naturais Bioativos, Departamento de Química, Universidade Federal Rural de Pernambuco, Av. Dom Manoel de Medeiros, s/n, 52171-900 Recife, Pernambuco, Brazil article info Article history: Accepted 29 April 2011 Keywords: Biorational control Mold mite Stored grains Fumigation Susceptibility abstract The fumigant activity of essential oils from Cinnamomum zeylanicum, Eugenia uniflora, Eugenia uvalha, Melaleuca leucadendra, Piper marginatum, and Schinus terebinthifolius was evaluated for control of the mites Tyrophagus putrescentiae (Schrank) and Suidasia pontifica Oudemans. The average mortality, after 24 h of exposure to oil of C. zeylanicum at the highest concentration tested (50 mL/L of air), was 97.7 and 92.9% for T. putrescentiae and S. pontifica, respectively. Mortality of the two species at the same concentration of S. terebinthifolius was 86.7 and 100%, respectively. As measured by LC 50 , the most toxic oil for T. putrescentiae was eugenol (0.23 mL/L air) followed by C. zeylanicum (0.82 mL/L air), E. uvalha (3.71 mL/L air), and S. terebinthifolius (8.25 mL/L air). The most toxic oil for S. pontifica was eugenol (0.57 mL/L air) followed by C. zeylanicum (1.75 mL/L air), S. terebinthifolius (4.87 mL/L air), and E. uvalha (11.09 mL/L air). Both mite species responded faster to S. terebinthifolius than to the other essential oils. Published by Elsevier Ltd. 1. Introduction The mites Tyrophagus putrescentiae (Schrank) and Suidasia pontifica Oudemans (Acari: Astigmata) are cosmopolitan species commonly associated with stored products in Brazil (Moraes and Flechtmann, 2008). These mites can infest many stored products, including grains, cheeses, nuts, dried fruits, seeds, feed, tobacco, and flours (Hughes, 1976; Sinha, 1979; Moraes and Flechtmann, 2008). They are of particular importance in tropical regions (Sánchez-Ramos and Castañera, 2005). Although these mites usually prefer stored products already infested by fungi (Parkinson et al., 1991; Hubert et al., 2003), their rapid reproduction can have economic conse- quences. They also cause allergic reactions in humans (Kondreddi et al., 2006) and disseminate toxigenic fungi (Hubert et al., 2004). Mite control practices in warehouses usually include various acaricides (Eaton and Kells, 2009), which have mixed results (Stables, 1984; Collins, 2006). Another form of control is through modified atmospheres (Conyers and Bell, 2003) and the fumigants phosphine, methyl bromide, and sulfuryl fluoride (Bowley and Bell, 1981; Bell et al., 2004). Phosphine has severe restrictions due to safety and environmental considerations (Fields and White, 2002) and methyl bromide and sulfuryl floride are not currently available for use in Brazil. Permethrin, pyriproxyfen, and benzyl benzoate can give some control of these mite species (Hubert et al., 2007), but in the past repeated insecticide usage led to resistant populations of T. putrescentiae (Wilkin, 1979; Stables, 1984). Plant-derived extracts and essential oils may be options for mite control (Isman, 2000; Lee et al., 2006). Plant-derived alkalis, alco- hols, aldehydes, terpenoids, and some monoterpenoids show fumigant properties (Macchioni et al., 2002). There are several recent studies with plant essential oils for control of stored prod- ucts pests (Kim et al., 2003a; Lee et al., 2006; George et al., 2010). Kim et al. (2003b) tested 54 plant essential oils regarding acaricidal effects on T. putrescentiae. The biological activity of Cinnamomum zeylanicum was investigated on Psoroptes cuniculi (Delafond) (Fichi et al., 2007) and the antibacterial activity of the essential oil of Schinus terebinthifolius was demonstrated against staphylococcal isolates from dogs (Silva et al., 2010). As part of a systematic study to evaluate the acaricide potential flora from the State of Pernam- buco, Brazil, oils from the species C. zeylanicum (Blume.), Eugenia uniflora (Berg.), Eugenia uvalha (Cambess.), Melaleuca leucadendra L., Piper marginatum (Jacq.), and S. terebinthifolius were assessed for acaricidal activity. * Corresponding author. Tel.: þ55 81 33206205; fax: þ55 81 33206205. E-mail address: cpoassis@hotmail.com (C.P.O. de Assis). Contents lists available at ScienceDirect Journal of Stored Products Research journal homepage: www.elsevier.com/locate/jspr 0022-474X/$ e see front matter Published by Elsevier Ltd. doi:10.1016/j.jspr.2011.04.005 Journal of Stored Products Research 47 (2011) 311e315