Swab vs rollers: a comparison of methods to collect eDNA from vegetative surfaces

Environmental DNA can be collected from vegetative surfaces circumventing the need for extensive equipment and multiple visits as often required by other sampling methods. This approach potentially offers a cost-effective and time-efficient means of capturing genetic material that can be used to provide valuable insights into terrestrial biodiversity. However, the effect of the material used to collect the sample is unknown. Here we compare the suitability of both clinical swabs and mini paint rollers to collect eDNA from vegetative surfaces in a bushland reserve in Western Australia. Both methods detected diverse eukaryote communities. There were no significant differences in ZOTU richness or community composition between the approaches, although the paint rollers had slightly higher cumulative richness. The choice between the two methods will likely be determined by logistical constraints: paint rollers are more expensive, bigger, and may be more susceptible to contamination but sample a greater surface area and can be readily attached to poles to access difficult to reach areas. Clinical swabs come sterile, are relatively small, and cheaper, but have limited reach and would require modification of poles. Although the sample size was small, results presented here can help guide future surface-based eDNA studies.