Changing markets - Medicinal plants in the markets of La Paz and El Alto, Bolivia.

ETHNOPHARMACOLOGICAL RELEVANCE: Given the importance of local markets as a source of medicinal plants for both healers and the population, literature on market flows and the value of the plant material traded is rather scarce. This stands in contrast to wealth of available information for other components of Bolivian ethnobotany. The present study attempts to remedy this situation by providing a detailed inventory of medicinal plant markets in the La Paz-El Alto metropolitan area, hypothesizing that both species composition, and medicinal applications, have changed considerably over time.

MATERIALS AND METHODS: From October 2013-October 2015 semi-structured interviews were conducted with 39 plant vendors between October 2013 and October 2015 in the Mercado Rodriguez, Mercado Calle Santa Cruz, Mercado Cohoni, Mercado Cota Cota, and Mercado Seguencoma and Mercado El Alto in order to elucidate more details on plant usage and provenance. The results of the present study were then compared to previous inventories of medicinal plants in La Paz and El Alto studies to elucidate changes over time and impact of interview techniques.

RESULTS: In this study we encountered 163 plant species belonging to 127 genera and 58 families. In addition, 17 species could not be identified. This species richness is considerably higher than that reported in previous studies (2005, 129 species of 55 families; 2015, 94 identified species). While the overall distribution of illness categories is in line with older reports the number of species used per application, as well as the applications per species, were much higher in the present study. Overall, informant consensus was relatively low, which might be explained by the large number of new species that have entered the local pharmacopoeia in the last decade, although some species might simply have been missed by previous studies. In course of the present study it became apparent that even well known species might often be replaced by other apparently similar but botanically unrelated species due to environmental and market forces CONCLUSIONS: The present study indicated that, while the floristic composition of markets in the La Paz metropolitan area remained relatively constant over the last decade, with this inventory adding about 20% of species to previous studies, the number of indications for which certain species were used increased tremendously, and that profound differences exist even between markets in close proximity. The dramatic increase in previously not used species used per indication might pose serious risks for consumers. We found serious problems due to species replacements. Even plants that have a well established vernacular name, and are easily recognizable botanically, can be replaced by other species that can pose a serious health risk. Vendor education and stringent identification of the material sold in public markets are clearly needed.