Does your preservative preserve? A comparison of the efficacy of some pitfall trap solutions in preserving the internal reproductive organs of dung beetles

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.