Cooled Propylene Glycol as a Pragmatic Choice for Preservation of DNA From Remote Field-Collected Diptera for Next-Generation Sequence Analysis

Next-generation sequencing (NGS)-based methods can now be applied to large population-scale studies, but this demands very high-quality DNA. For specimens collected from remote field locations, DNA degradation can be a problem, requiring logistically challenging preservation techniques. Simpler preservation techniques are therefore required. Prior to collection of exotic fruit fly (Tephritidae) species, a number of readily available preservatives with storage at either 4 degrees C or room temperature were trialed here to determine the DNA quality for three locally available Diptera species, Fannia canicularis (L.), Musca domestica L., and Lucilia sericata Meigen. Considerable variation was observed between the different preservatives, species, and temperatures, but several preservatives at 4 degrees C were favored. Chilled propylene glycol was subsequently used for the storage and carriage of Australian field-collected Bactrocera fruit fly specimens to New Zealand. When processed up to 20 d later, DNA fragments of similar to 10-20 kb were obtained for successful genotyping by sequencing analysis. This protocol is therefore recommended as a logistically simple and safe approach for distant collection of dipteran samples for NGS population genomic studies.