Context of the Study
The coypu, Myocastor coypus, is a semi-aquatic mammal native to South America. The species was deliberately introduced to many regions of the world, mainly for the fur trade, but also for its ability to keep navigable canals free of vegetation.
Currently, the coypu is considered an invasive alien species in Asia, East Africa, North America, and Europe. In these regions, wild populations have resulted from deliberate releases or escapes from breeding farms.
The establishment of wild populations of this invasive species poses several major risks to local biodiversity.
On one hand, the creation of galleries and burrows in riverbanks can lead to landslides and land subsidence. On the other hand, its high consumption of aquatic plants causes a reduction in habitats and breeding areas for many species, leading to a loss of biodiversity in invaded areas. Finally, the coypu is a vector of Leptospira, a bacterium responsible for leptospirosis.
Based on the ISEIA (Invasive Species Environmental Impact Assessment) protocol, the coypu is classified as category A1 in Belgium. The species is thus present in isolated populations across the territory, while having a strong impact on the environment. Therefore, this species requires appropriate management measures to limit its spread on the territory.
As part of a thesis conducted at the University of Liège in collaboration with the Public Service of Wallonia, E-BIOM developed a detection protocol for the coypu based on environmental DNA sampling.
Sampling and Laboratory Analysis
Samples were taken from different types of aquatic environments (former Sambre ditch, ponds, and rivers) using environmental DNA methods. This technique involves recovering traces of DNA released by coypus (faeces, urine, mucus) into their environment by filtering water through a capsule using a peristaltic pump.
Sampling was carried out on sites where the presence of the coypu had been confirmed through visual observation.
In the laboratory, the DNA contained in the filtration capsules was extracted and then amplified by quantitative PCR (qPCR) using species-specific primers developed by E-BIOM for Myocastor coypus.
To ensure the quality of our analyses and the reliability of our data, positive and negative controls were conducted at each stage to validate the experimental process.
Results and Conclusion
The results obtained in the laboratory are in perfect agreement with the observations made in the field. We obtained positive signals for all study sites where the presence of the coypu had been confirmed. Conversely, our method confirmed the absence of the species at several sites. The data are therefore conclusive: the environmental DNA method allows the rapid detection of coypu.
Our goal is to apply this method to precisely study the distribution area of Myocastor coypus populations and thus monitor areas potentially in the process of colonization without having to rely on direct observation of the species. Indeed, coypu tracks are sometimes difficult to differentiate from those of the muskrat (Ondatra zibethicus) or the Eurasian beaver (Castor fiber).
