Invasive species cause severe impacts on biodiversity losses, among them, emerging diseases caused by parasites are also considered as invasive species. Varroa destructor is an ectoparasite mite native from South-East Asia and has spread all over the world since the early 50's. The mite is considered as the main sanitary threat for honeybee health worldwide. This parasite was detected for the ¿rst time in the islands of the South-West Indian Ocean (SWIO): 2010 in Madagascar, 2014 in Mauritius and 2017 in La Reunion. The aims of this work were (i) to characterize the genetic diversity of the parasite on the three islands, (ii) to assess the mortalities within honeybee population after the detection of V. destructor and (iii) to assess the spread of the parasite and identify the associated drivers. To identify the parasite strain and its diversity, mitochondrial DNA sequences were analyzed. Sanitary and epidemiological surveys were conducted in Madagascar, Mauritius and La Reunion. The varroa strain identi¿ed in the SWIO area was the invasive K strain, nevertheless several haplotypes were retrieved, among which one was common in Madagascar, Mauritius and La Reunion. The parasite invsasion increased signi¿cantly the mortalities in the honeybee populations (for example, +185% of mortalities were observed in La Reunion). Beekeepers played a major role in dispersing the parasite within the islands and the dispersion speed estimated was higher in La R´eunion and Mauritius than in Madagascar where the beekeeping practices are really di¿erent (modern vs. traditional). Varroa mite eradication cannot be an option for local beekeepers and several control options should be considered. Several other sanitary threats such as Aethina tumida (small hive beetle) and Paenibacillus larvae (American foulbrood) threaten the honeybees from the SWIO islands. In this insular context, routes of introduction have to be identi¿ed and the sanitary surveillance tools should be improved for all t