Hugo de Boer
Illegal international trade threatens many species. However, the telling one species from another can present a huge challenge.
This is particularly true for groups like orchids, as there are more than 30,000 species! Customs agents, traders and consumers are often unable to identify which species they are dealing with. This uncertainty often benefits smugglers, who misidentify species, both to cause intentional confusion and through ignorance. In the case of salep, a food made from dried orchid tubers that is popular from Greece to Iran and among its cultural diaspora, the challenge of detection and identification of illegal trade is especially hard. It can be almost impossible to give a positive species based on dried tubers and once they have been ground into flour.
Dried salep orchid tubers from Urmia, western Iran. Photo credit: Abdolbaset Ghorbani.
DNA is increasingly used in wildlife forensics and species identification to tackle illegal wildlife trade. It has proven its use in uncovering and tracing illegal trade of elephant ivory, rhino horn and pangolin scales. It is now also being used to address illegal orchid trade.
Using a method called metabarcoding, we are able to identify not only individual orchid tubers to species level, but also to tease out the diversity of orchids in ground salep powder. The method uses standard DNA barcoding markers combined with high-throughput sequencing to assess the total species diversity in a given salep mixture.
Using this method to analyze 55 commercial salep products purchased in Iran, Turkey, Greece and Germany, we identified 161 different plant taxa from 35 products. Only thirteen of these salep products contained orchids, but these were of many different species. In the salep powders, we found combinations of 10 species of terrestrial orchid with tuberous roots in the genera Dactylorhiza, Orchis, Anacamptis and Gymnadenia. Furthermore, 70% of the products contained the substitute ingredient, the bean Cyamopsis tetraganoloba (Guar).
Milk-boiled dried salep orchid tubers from Maraveh Tappeh, northern Iran. Photo credit: Abdolbaset Ghorbani.
This DNA analysis elucidates the diversity of taxa that are targeted, and presence of rare species or species with limited distributions that can help to track and trace vulnerable populations. Surprisingly, it also shows that illegal trade and fraud go hand-in-hand, with many products not containing any detectable orchid DNA, but instead of diversity of substitutes with similar gelatinous properties.
Understanding the species diversity and provenance of salep orchid tubers can help us to identify threatened and endangered species that are affected by commercial trade. We can use it trace the trade chain back to harvesters and their natural habitats, and thus allows for targeted efforts to protect or sustainably use wild populations of these orchids. Further research will aim to enhance the species identification resolution and quantify the concentrations of individual species in mixtures. This opens up new opportunities for using DNA analysis to improve the conservation of hard-to-identify groups such as orchids.
Hugo de Boer. Photograph by Karsten Sund
Prof. de Boer’s is a researcher at the Natural History Museum, University of Oslo.
Twitter: @Hugo_deBoer
For more information see: De Boer, H.J., Ghorbani, A., Manzanilla, V., Raclariu, A.C., Kreziou, A., Ounjai, S., Osathanunkul, M. and Gravendeel, B., 2017. DNA metabarcoding of orchid-derived products reveals widespread illegal orchid trade. Proceedings of the Royal Society B: Biological Sciences, 284 (1863), p.20171182.