Galleria mellonella as a novel in vivo model for assessment of the toxicity of 1-alkyl-3-methylimidazolium chloride ionic liquids Julianne Megaw, Thomas P. Thompson, Ryan A. Lafferty, Brendan F. Gilmore ⇑ School of Pharmacy, Queen’s University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK highlights  A novel, sensitive in vivo model for ionic liquid toxicity is presented.  LD 50 concentrations of nine ionic liquids to G. mellonella were determined.  Toxicity was directly influenced by ionic liquid alkyl chain length.  G. mellonella appears to be an ideal model for the study of ionic liquid toxicity. article info Article history: Received 20 February 2015 Received in revised form 12 May 2015 Accepted 5 June 2015 Keywords: Ionic liquids Toxicity Galleria mellonella Insect model abstract The larval form of the Greater Wax Moth (Galleria mellonella) was evaluated as a model system for the study of the acute in vivo toxicity of 1-alkyl-3-methylimidazolium chloride ionic liquids. 24-h median lethal dose (LD 50 ) values for nine of these ionic liquids bearing alkyl chain substituents ranging from 2 to 18 carbon atoms were determined. The in vivo toxicity of the ionic liquids was found to correlate directly with the length of the alkyl chain substituent, and the pattern of toxicity observed was in accordance with previous studies of ionic liquid toxicity in other living systems, including a characteristic toxicity ‘cut-off’ effect. However, G. mellonella appeared to be more susceptible to the toxic effects of the ionic liquids tested, possibly as a result of their high body fat content. The results obtained in this study indicate that G. mellonella represents a sensitive, reliable and robust in vivo model organism for the evaluation of ionic liquid toxicity. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction Ionic liquids are salts in which the ions are poorly-coordinated, resulting in them existing in a liquid state below 100 °C, and even at or below room temperature in some cases (Welton, 1999). These low temperature molten salts possess numerous unique properties as solvents, such as excellent solvation capacities, thermal, atmo- spheric, and moisture stability and non-volatility (Hallett and Welton, 2011), which has led to the perception of ionic liquids as ecologically friendly alternatives to more conventionally used volatile organic solvents. Ionic liquids possess an almost limitless capacity for tunability, and these customisable, so-called ‘‘designer solvents’’ have a broad range of potential applications including synthesis, catalysis (Hallett and Welton, 2011), energy production (Zhang et al., 2014), and pharmaceuticals (Ferraz et al., 2011). Despite some clear advantages in industrial applications, and their frequent labelling as ‘‘green’’ owing to their non-volatility, some of the other properties of ionic liquids are less desirable. Clearly, however, given the almost limitless flexibility in their design, with over one million simple ionic liquids available (Seddon, 1999), labelling this class of compounds either ‘green’ or ‘toxic’ represents a gross overgeneralization, which is neither warranted nor accurate (Petkovic et al., 2011). Numerous ionic liq- uids exhibit wide-ranging toxicity, and in some cases have been shown to be more toxic than the solvents for which they are poten- tial replacements (Docherty and Kulpa, 2005). Many ionic liquids are water soluble, and the high stability of these compounds is fre- quently reflected in a general recalcitrance to biodegradation; studies have occasionally reported complete biodegradation, but have more often reported relatively low or incomplete elimination of these compounds (Stolte et al., 2008; Coleman and Gathergood, 2010; Abrusci et al., 2011; Deive et al., 2011; Megaw et al., 2013; http://dx.doi.org/10.1016/j.chemosphere.2015.06.026 0045-6535/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail addresses: jmegaw01@qub.ac.uk (J. Megaw), tthompson08@qub.ac.uk (T.P. Thompson), rlafferty04@qub.ac.uk (R.A. Lafferty), b.gilmore@qub.ac.uk (B.F. Gilmore). Chemosphere 139 (2015) 197–201 Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere