The effects of ethylene glycol and ethanol on the body mass and elemental composition of insects collected with pitfall traps Mihály Braun a , Edina Simon b, * , István Fábián a , Béla Tóthmérész b a Department of Inorganic and Analytical Chemistry, University of Debrecen, H-4032 Debrecen, Egyetem tér 1, Hungary b Department of Ecology, University of Debrecen, H-4032, Debrecen, Egyetem tér 1, Hungary article info Article history: Received 14 May 2009 Received in revised form 27 August 2009 Accepted 28 August 2009 Available online 4 October 2009 Keywords: Bioindicators Heavy metals Pitfall trapping Ethylene glycol Ethanol Elemental analysis abstract Insects often used as accumulation indicators of hazardous elements. Pitfall traps with ethylene glycol as trapping fluid are frequently used to collect insects. We studied the effect of glycol and preservation with ethanol on the elemental composition of hand collected firebugs. Control samples were stored in a freezer and the following treatments were used: insect kept in trapping fluid for 2 weeks, and for 1 month, trap- ping fluid for 2 weeks plus 2 weeks in ethanol, and trapping fluid for 1 month plus ethanol for 1 month. Insects kept in trapping fluid gained mass with respect to control: 26% for the short trapping and 37% for the long trapping. Preservation in ethanol reversed this effect in each case. Trapping fluid did not alter the dry mass. A significant loss in dry mass only occurred in the long trapping plus long preservation treat- ment. We analysed the concentration of eight elements: Ca, Cu, K, Mg, Mn, Na, Sr and Zn. We found sig- nificant difference in the concentrations of elements among the four treatments in the case of all elements, except magnesium and zinc. Our results indicate the potential of both certain trapping fluids as well as preservation in ethanol influencing the concentration of certain elements in insects. Live trap- ping for collection and storage in under freezing conditions for preservation could be a more reliable method if quantitative analytical studies are to be performed, when invertebrates are used as indicators of the presence and concentrations of hazardous substances in the environment. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Insects play an important role in most terrestrial environments owing to their great abundance, biomass and diversity (Zödl and Wittmann, 2003). Furthermore, they represent important links in metal-transport chains among trophic levels (Rabitsch, 1995; Lindqvist and Block, 1998). Therefore, trace-metal concentrations in insects have an important influence on the distribution of trace-elements in the biosphere (Lindqvist and Block, 1997). Inver- tebrates have also been widely used as bioindicators in environ- mental studies. The habitats of ground-living species are in close contact with soils (Nakamura et al., 2005), and these animals may accumulate inorganic and organic toxic compounds. The life cycle of invertebrates is usually short and their collection is easy making them suitable as indicators of concentration of environ- mental contaminants (Zödl and Wittmann, 2003). Insects are also common in urban environments and they can be used to indicate the presence and concentrations of pollutants. The use of invertebrates, in particular insects, as biological indi- cators of environmental pollutants started to attract attention dur- ing the past decade. Accumulation of metals in different developmental stages of invertebrates has been studied under lab- oratory conditions in order to explore physiological mechanisms and toxicity issues (Devkota and Schmidt, 1999; Maryanski et al., 2002). Other researchers emphasise the usefulness of these ani- mals for biomonitoring of metal pollutants in field studies (Lagisz et al., 2002; Nahmani and Rossi, 2003; Pearce and Venier, 2006). Different methods are used to collect terrestrial invertebrates. Hand collecting is the most appropriate way to collect animals for elemental analysis, but this is not always effective nor repre- sentative (Leather, 2005). Pitfall trapping is a simple and wide- spread method for sampling flightless or ground-living insects. This collection method is inexpensive, easy to use and operate round the-clock, resulting in large, species-rich samples (Clark and Blom, 1992). The common pitfall trap is typically a small plas- tic or glass container, which is placed in a hole with the upper rim flush with the ground surface and contains an amount of killing- preserving agent. Various substances have been used as killing agents in the traps (Southwood and Henderson, 2000; Schmidt et al., 2006; Jud and Schmidt-Entling, 2008; Thomas, 2008) e.g. eth- anol solution (Giles et al., 1973; Strojan, 1978; Pyatt et al., 1999; Nakamura and Taira, 2005) and formalin (Roberts and Johnson, 1978; Hunter et al., 1987; van den Berghe, 1992; Eichinger et al., 2007). However, formalin and picric acid are also used infrequently because of associated health hazards. Propylene glycol is a 0045-6535/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2009.08.051 * Corresponding author. Tel.: +36 52 512 900/22603; fax: +36 52 431 148. E-mail address: edina.simon@gmail.com (E. Simon). Chemosphere 77 (2009) 1447–1452 Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere