Dr Cecilia Villacorta-Rath1,2, Dr Samantha Tol3, Mr Carl Shuetrim3, Professor Lori Lach2,3
1Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER), James Cook University, Townsville, Australia, 2Centre for Tropical Biosecurity, James Cook University, Australia, 3College of Science and Engineering, James Cook University, Cairns, Australia
Biography:
Cecilia is the leader of the Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER) eDNA Laboratory at James Cook University. Specializing in biosecurity and threatened species detection, Cecilia leads innovative work that ranges from detection of invasive ant species to monitoring the movement of sea turtles using eDNA methods. Her lab focuses on adapting field methods to enable citizen scientists, Indigenous rangers, and Traditional Owners to conduct eDNA sampling in remote areas of northern Australia. Cecilia's mission is to equip stakeholders with a diverse toolkit for the detection and management of invasive and endangered species, ensuring a proactive approach to preserving biodiversity.
Abstract:
The ecology of environmental DNA (eDNA) in aquatic systems has been widely studied. A large amount of literature on aquatic eDNA shedding rates, degradation and transport is now available. However, most studies available on terrestrial ecosystems are based on eDNA metabarcoding. Here, we used a targeted approach on an invasive terrestrial invertebrate to determine: (1) eDNA detection threshold in soil; (2) eDNA degradation in soil under two different temperature treatments (25°C, 40°C) during a 14-day period; and (3) eDNA degradation under two different UV treatments (no UV, full UV) during a 28-day period. For the detection threshold experiment, we exposed clean soil to five experimental yellow crazy ant colonies (Anoplolepis gracilipes) for nine days. We found target species’ eDNA in clean soil from the first day after exposure. For both eDNA degradation experiments, we exposed clean soil to ten experimental yellow crazy ant colonies. Temperature did not have a significant effect on eDNA decay and there were no significant differences in the percentage of positive detection and eDNA concentrations between treatments. Under both 25°C and 40°C, eDNA was still detectable in soil 14 days after being shed. Conversely, UV radiation did have a significant effect on eDNA degradation in soil, with eDNA becoming undetectable after 14 days of exposure. Our results suggest that ant eDNA persistence in soil is more influenced by UV exposure than by temperature. Therefore, considering the habitat in which the target ant species is most active will be useful in designing an eDNA sampling regime.