Researchers discover five new parasite species in rain forests
A world-renowned expert in the field of flatworm parasites and researcher of note from the North-West University (NWU) discovered five new parasites in different species during a recent research mission in the rain forests of South America.
Prof Louis du Preez of the School of Environmental Sciences at the Potchefstroom Campus said that these species of parasites (Polystomatidae) were found in an earthworm-like worm amphibian (caecilian) and in turtles.
He said that in 2008 he described the first polystome that had been found in a worm amphibian that had been preserved for 120 years in a bottle of formalin in a museum in Scotland. DNA could not be extracted, as the formalin had destroyed the DNA.
The aim of the research mission to the Amazon was to find this kind of polystome in a caecilian so that DNA could be extracted. "We knew beforehand that chances of finding this caecilian were slim, and those of finding the parasite in one even slimmer.”
Prof Louis said he undertook this journey to Guiana in South America in collaboration with the French National Centre for Scientific Research (CNRS) and was accompanied by Olivier Verneau of the CNRS and a postdoctoral student, Mathieu Badets. They first stayed at the CNRS base in Cayenne before they tackled the trip of 120 kilometres upstream on the Approuague River in a “banana boat”. The French have a research base in the Nouraques Reserve next to the river. The base is situated only four degrees north of the equator.
The base is very remote and he said they had to take all their equipment and microscopes with them. However, the base is very well equipped with basic infrastructure and food that is kept in freezers.
Prof Louis said they were allowed to catch only two kinds of aquatic tortoises. "We knew polistomae had never been found in these tortoises."
The tortoises were kept in containers filled with water, after which the water was examined for the parasites. They found four new species in the water, and another was found in a frog in the forest.
Three aquatic caecilians were also caught in the reserve and in one of the caecilians they found the scarce polystome. "Now, at last, after 120 years, we can extract the DNA from the parasites to see where they phylogenetically fit into the evolutionary development process.”
According to Prof Louis they can establish how the parasites developed and how they spread across the earth over geological time, because this group of parasites is very species-specific and fastidious. Amphibians are the first group of vertebrates that moved onto dry land, even before dinosaurs. “The parasites found in the group of aquatic animals consequently give us a good indication of when this movement occurred in geological time.”
He said the find would keep them busy authoring research articles for at least the following year.
“It was an incredible place to do research and we have been invited by the CNRS to visit the base again.”
Prof Louis, who is also an expert on frogs, said he was surprised by the wide variety of frogs found in the rain forests.
Guiana in South America has only 300 000 inhabitants and only the parts along the coast are inhabited. The Nouraques Reserve is located along the Approuague River.
The journey of 120 kilometres upstream on the Approuague River was undertaken in a “banana boat”. All equipment, like microscopes, had to be taken with and because it rained every day, everything had to be covered.
The worm-like caecilian in which the rare polystome was found.
A microscopic image of a polystome.
The “rooms” in which the researchers slept in the research base of the Nouraques Reserve.
Prof Louis du Preez behind the microscope in the research base.
Prof Louis du Preez with one of the frog species in the rain forest.
Some of the interesting frog species found in the Nouraques Reserve.