These traditional methods are often cumbersome and inefficient.
Instead, the researchers collect leeches when they eagerly come to them for a blood meal. Afterwards, the leeches' "bloody appetites" are analysed for DNA. In this way, the researchers get a genetic identification of the mammal host species, which the leeches have been sucking blood from.
Veterinarian Mads Bertelsen, Copenhagen Zoo, explains how he came on to the idea of analysing blood from leeches.
"It was in a Zoo project in Malaysia on monitoring and tracking of tapirs that we started thinking about the possibilities. Leeches in the jungle attacked one of my colleagues, and the idea was born. Then we contacted DNA researchers at GeoGenetics, University of Copenhagen, to explore the perspectives directly. First, we used 20 medical leeches fed with goat blood from the Zoo. It turned out that the leeches contained traces of goat DNA for more than four months after eating. Then we knew we were on to something," says veterinarian Mads Bertelsen from Copenhagen Zoo.
"It is an alternative way of monitoring mammalian wildlife. Leeches come to you with the blood samples, rather than you tracking down the animals in the jungle. Simple and cheap, and the sampling does not require specially trained scientists, but can be carried out by local people. I am convinced that this technique will revolutionise the monitoring of threatened wildlife in rainforest habitats," says Mads Bertelsen.
Next step in the project was to collect leeches from a Vietnamese rainforest and analyse them for mammal DNA. 21 of 25 leeches contained DNA traces from local mammal species. Some of them were even very rare species. Among the catch was a ferret-badger, a deer, a goat-antelope and the Annamite striped rabbit. The latter was particularly exciting, as it was first discovered in 1996, however, has not been seen in this area since, despite 2,
|Contact: Philip Francis Thomsen|
University of Copenhagen