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

Abstract

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.

Searching for the Optimal Sampling Solution: Variation in Invertebrate Communities, Sample Condition and DNA Quality

“…We tested only the three most commonly used solutions in current biodiversity studies. Recently, Pokluda et al [ 31 ] recommended to use 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. Its attracting effect has, however, not been tested and while it may be good for DNA it is unknown if community biases (as we found for Renner) might occur.…”

“…Previous studies suggest that specimens sampled by different sampling solutions highly differ in their effects on DNA quality and genotyping reliability. These studies were, however, either conducted under laboratory conditions [ 5 , 30 ], used only one sampling solution [ 31 ] or used only a short exposition time to avoid evaporation issues when using ethanol [ 32 ] which is not practicable in most biodiversity projects.…”

A review of extensive variation in the design of pitfall traps and a proposal for a standard pitfall trap design for monitoring ground‐active arthropod biodiversity

“…For example, Pokluda et al. () have recently shown that 2% SDS and 100 mmol/L EDTA solutions are capable of preserving the DNA of Coleoptera for up to 8 weeks and recommend these for use by entomologists interested in collecting material for barcoding, while Miller et al. () described a method that allowed extraction of DNA from arachnid specimens stored in 70% ethanol for up to 50 years (with varying success depending on the age and body size of the specimen).…”

“…The problem in suggesting a standardized killing preservative is that both the literature on the preservation ability of different preservatives and the techniques to extract DNA from old or degraded specimens is advancing rapidly. For example, Pokluda et al (2014) have recently shown that 2% SDS and 100 mmol/L EDTA solutions are capable of preserving the DNA of Coleoptera for up to 8 weeks and recommend these for use by entomologists interested in collecting material for barcoding, while Miller et al (2013) described a method that allowed extraction of DNA from arachnid specimens stored in 70% ethanol for up to 50 years (with varying success depending on the age and body size of the specimen). The effort of undertaking field studies to investigate how these new preservatives influence capture rates represents a considerable challenge.…”

Biodiversi-TEA—A quick and easy handling method for arthropod trap material in ethanol

“…Biodiversi-TEA enables the safe, easy and quick handling and temporary storage of samples, which can later be separated from the filter bags in the lab. Quantities of ethanol that can be transported during flights are strictly regulated (Pokluda et al 2014). Our method allows one to easily discard ethanol from the samples and the SteriBags can be easily stored in stable plastic boxes to avoid damage ( Fig.…”