Varroa destructor invasion in the South West Indian Ocean islands and its mortality impacts on the endemic honeybee subspecies Apis mellifera unicolor in Madagascar, Mauritius and La Reunion

Esnault Olivier, Sookar Preeaduth, Razafindraibe Nivohanitra Perle, Chauzat Marie-Pierre, Delatte Hélène. 2019. Varroa destructor invasion in the South West Indian Ocean islands and its mortality impacts on the endemic honeybee subspecies Apis mellifera unicolor in Madagascar, Mauritius and La Reunion. In : Book of abstracts talks of of the third international conference on Island ecology, evolution and conservation. Flores Olivier (ed.), Ah-Peng Claudine (ed.), Wilding Nicholas (ed.). Université de la Réunion. Saint-Denis : Université de la Réunion, Résumé, 167. International conference on Island ecology, evolution and conservation. 3, Saint-Denis, Réunion, 8 Juillet 2019/13 Juillet 2019.

Résumé : 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 first 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 identified 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 significantly 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 different (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 identified and the sanitary surveillance tools should be improved for all the islands.

Auteurs et affiliations

• Esnault Olivier, GDS Réunion (REU)
• Sookar Preeaduth, Ministry of Agro Industry and Food Security (Maurice) (MUS)
• Razafindraibe Nivohanitra Perle, DSV (MDG)
• Chauzat Marie-Pierre, ANSES (FRA)
• Delatte Hélène, CIRAD-BIOS-UMR PVBMT (REU)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/594148/)

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