A goodbye letter to alcohol: An alternative method for field preservation of arthropod specimens and DNA suitable for mass collecting methods

Abstract

Despite its limitations, ethanol remains the most commonly used liquid for the preservation of arthropod specimens and their DNA in the field. Arthropod ecology and taxonomy have witnessed a substantial increase in the use of various trapping and molecular methods in the past two decades. However, the methods of collecting and the preservation liquids most widely used in arthropod traps do not properly preserve DNA. Trap-collected specimens are typically of limited utility for molecular studies due to the poor preservation of DNA. A stable and cheap substance that can be used to trap arthropods in and preserve their DNA is therefore needed. Here we test whether (i) 2% SDS, 100mM EDTA, (ii) 1% SDS, 50mM EDTA and (iii) 0.66% SDS, 33mM EDTA can preserve DNA of small and medium-sized beetles for one, four and eight weeks. Preservation of DNA was tested using PCR amplification of parts of the mitochondrial cytochrome c oxidase I (Cox1) and nuclear 28S rRNA genes. All the solutions tested preserved DNA for at least up to eight weeks and we recommend 2% SDS and 100mM EDTA as a cheap, stable and easily transportable alternative to ethanol for preserving specimens and their DNA collected in the field. This solution is also suitable for using as the collection and preservation liquid in arthropod traps.

Keywords

• insects
• beetles
• dna preservation
• flight intercept traps
• malaise traps
• pitfall traps