Effects of pitfall trap preservatives on specimen condition in carabid beetles

Pitfall trapping is one of the most widely used methods for sampling ground-dwelling insects (Gullan & Cranston, 2004). The type of preservative used in pitfall traps may affect not only the sampling efficiency but also the condition of the samples (Lemieux & Lindgren, 1999; Schmidt et al., 2006). Furthermore, the type of preservative may affect the suitability of samples for further investigation, as demonstrated by a molecular study of spiders (Gurdebeke & Maelfait, 2002) and measurements of heavy metal concentrations in woodlice (Hendrickx et al., 2003). In most insects, the condition of the gonads (e.g., egg maturation) and morphology of the genitalia can provide useful information. Gonad condition is often used to estimate reproductive season (Loreau, 1985; Telfer & Butterfield, 2004) or as an index of parental investment (Morrow & Gage, 2000; Simmons & Emlen, 2006). The morphology of the genitalia can be examined for valuable taxonomic (Sasakawa & Kubota, 2005; Takami & Sota, 2006), phylogenetic (Sasakawa, 2005; Sota et al., 2005), and/or functional (Pitnick et al., 1999; Sasakawa, 2006) information. However, to date, no studies have examined the effects of preservatives on the condition of internal organs (e.g., gonads and genitalia) in collected samples. This study provides the first descriptions of such effects of pitfall trap preservatives on the morphologies of gonads and genitalia, using three carabid species.