Abstract
Eight pitfall trap preservatives, brine, saturated borax solution, propylene glycol (33%, 50%, 75%), white vinegar, 100% ethylene glycol, FAACC (Formaldehyde 4%, Acetic acid 5%, Calcium chloride 1.3%), 4% phosphate buffered formaldehyde and 96% ethanol, were compared for their ability to preserve the internal reproductive organs of the dung beetle Liatongus militaris (Laporte) (Scarabaeidae: Scarabaeinae) for up to 28 days in the field. Relative evaporation rates of the preservatives in riparian vine thicket and low open woodland environments were also compared. 96% ethanol, FAACC and 4% phosphate buffered formaldehyde were the only solutions found to preserve all of the internal reproductive organs. Evaporation rates were lower in the vine thicket and some preservatives such as ethanol completely evaporated within seven days. 4% phosphate buffered formaldehyde is recommended as a preservative for pitfall traps left in the field for periods longer than one week. Possible ways to prevent trap interference by mammals and risks to the environment due to overspill are also discussed.
Highlights
Pitfall traps have long been recognised as an effective and inexpensive technique for sampling arthropods, including Coleoptera (Greenslade and Greenslade 1971; Gist and Crossley 1973; Luff 1975; Newton and Peck 1975; Topping and Sunderland 1992; Weeks and McIntyre 1997)
The efficiency of pitfall traps may be influenced by aspects of construction, such as shape, size and materials (Luff 1975; Brennan et al 1999); spacing and transect design (Luff 1975; Ward et al 2001; Perner and Schueler 2004; Larsen and Forsyth 2005); and the use of various baits, killing agents, and preservatives (Luff 1968; Greenslade and Greenslade 1971; Weeks and McIntyre 1997; Pekar 2002)
Various killing agents and preservatives are commonly used in pitfall traps, there is a lack of studies testing the efficacy of preservative type in preventing the decomposition of collected samples
Summary
Pitfall traps have long been recognised as an effective and inexpensive technique for sampling arthropods, including Coleoptera (Greenslade and Greenslade 1971; Gist and Crossley 1973; Luff 1975; Newton and Peck 1975; Topping and Sunderland 1992; Weeks and McIntyre 1997). Various killing agents and preservatives are commonly used in pitfall traps, there is a lack of studies testing the efficacy of preservative type in preventing the decomposition of collected samples. This gap in the literature is evident in regards to the deterioration of insects’ internal organs (Sasakawa 2007). A probable reason that this duration had not been investigated is that most researchers either service their pitfall traps within a few days of setting or baiting or do not require internal organs of specimens to be preserved
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