Dr Cecilia Villacorta-Rath1,2, Ms Johanna Karam3, Dr Samantha Tol4, Mr Carl Shuetrim4, Professor Lori Lach2,4
1Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER), James Cook University, Townsville, Australia, 2Centre for Tropical Biosecurity, James Cook University, Australia, 3Queensland Parks and Wildlife Service, Department of Environment, Science and Innovation, Cairns, Australia, 4College 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:
Invasive invertebrates are a risk to industry, social wellbeing, and lifestyle. Because eradicating or managing large populations is quite costly, early detection may prevent economic and environmental impacts. Environmental DNA has the potential to become an important tool to achieve early detection. However, having an appropriate sampling design will maximise species detectability. For eDNA detection of terrestrial invertebrates, the main questions arising are where and how to sample. When dealing with a terrestrial organism that does not need to come in contact with water to hydrate, the most logical point of sampling will be soil. However, we have demonstrated that terrestrial invertebrate eDNA can be detected in water after rainfall events.
We carried out three projects aimed at improving detection of yellow crazy ants (Anoplolepis gracilipes) and electric ants (Wasmannia auropunctata) in soil and water at sites in northern Queensland. We found up to 50% false negative detections (i.e., failure to detect target eDNA when the organism was observed in high density during sampling) in soil samples for both species, highlighting the need to refine sampling methods. However, eDNA of both species was detected in soil from sites where the ants had not been sighted. Target ant presence was subsequently confirmed via traditional methods. We also sampled water from 11 creeks in the dry tropics and eight creeks in the wet tropics adjacent to or downstream from yellow crazy ants or electric ants. The percentage of positive detections varied across sampling events possibly due to rainfall history and ant activity.