Origin of protected contraband leeches determined using metabarcoding

How molecular analysis and metabarcoding can be used to identify protected species and their potential origin

Hirudo verbana
Hirudo verbana observed near Lytkarino, Russia by Marina Gorbunova (CC BY-NC 4.0)

The Convention on International Trade in Endangered Species (CITES) oversees the movement of protected and endangered species across international borders. Some species can be traded provided necessary permits are obtained, and the source of the specimen is documented.

Travelling from Russia to Canada in October 2018, a passenger was discovered at Toronto International Airport carrying more than 4,000 live European medicinal leeches (Hirudo spp.). As CITES provides protection of two Hirudo species and as the source of the leeches was unclear, the Canadian authorities detained the animals for identification and determination of their source.

Researchers at the American Museum of Natural History identified the leeches as H. verbana (protected by CITES) using morphological and molecular techniques. To determine the origin of the animals, the researchers used genomic metabarcoding targeting vertebrate DNA from the blood meal in the guts of the leeches.

The analysis identified 16 distinct species—10 birds, four fish and two amphibians—none of which were domesticated animals, suggesting a wild origin. Using IUCN range maps combined with GBIF-mediated occurrences of the identified vertebrates, the researchers created a heat map of overlapping distributions, pointing to the Volga or Danube deltas as potential collection sites.

Williams KM, Barkdull M, Fahmy M, Hekkala E, Siddall ME and Kvist S (2020) Caught red handed: iDNA points to wild source for CITES-protected contraband leeches. European Journal of Wildlife Research. Springer Science and Business Media LLC 66(5). Available at: https://doi.org/10.1007/s10344-020-01419-5