The Westernmost Mediterranean islands present an endemic varroosis disease pattern

Abstract

Aim of study: This is the first intensive study of the incidence of Varroa destructor (Acari: Varroidae) in the Westernmost Mediterranean islands (Balearics). Area of study: Mallorca, Menorca, Eivissa and Formentera (Balearic Islands), Spain. Material and methods: The study was carried out in autumn 2010 and in spring 2011 because the presence of the mite is higher in these seasons. A total of 462 honeybee colonies were analyzed from different apiaries on. One sample of adult bees (worker bees, n > 200) and another of bee brood (at all stages of development, n> 400) were collected from each colony. All were frozen until analysis. To detect Varroa each sample was examined individually basing the study on the guide edited by the World Organisation for Animal Health, with some modifications. The beekeepers involved were interviewed to characterize Balearic beekeeping. Main results: Regarding the prevalence, results showed that in the Balearic Islands the percentage was higher in spring (34.78%) than in autumn (44.09%) but the infestation rate was lower in both seasons (Autumn: 0.94%, Spring: 0.77%). The focality percentage was also higher in spring (87.10%) than in autumn (82.61%). The data suggests that Varroa mites in the archipelago have an endemic rather than epidemic disease distribution pattern. Research highlights: These results open an interesting scenario to develop a future resistance breeding strategy against V. destructor in these small islands.