Spread and strain determination of Varroa destructor following its introduction to Mauritius and interactions with the bee louse Braula pretoriensis in honey bee colonies

Abstract

Honey bees are facing many serious threats, and Varroa destructor is of major worldwide concern. V. destructor was first observed in 2010 in the south–west Inidan Ocean island of Madagascar. Varroa spp. was first suspected in Mauritius in late July 2014. Two surveys were conducted in September and November 2014 in Mauritius and Rodrigues. The aims of these surveys were to confirm the presence of Varroa on Mauritius, determine the species and strain and to study its spread and interactions with the bee louse Braula pretoriensis. Honey bees were sampled from different sites. V. destructor and the bee louse Braula pretoriensis infestation rates were measured for each colony and apiary. V. destructor presence was confirmed and observed in the Central and Northern part of Mauritius, but was not detected in Rodrigues. B. pretoriensis was observed on both islands. V. destructor partial mitochondrial region of the CO1 showed that the Mauritius K strain found was different from the one from Madagascar. In Mauritius, B. pretoriensis numbers were significantly higher in colonies infested by V. destructor; however, bee louse infestation rates were similar in both islands in sites without the varroa mite. Although bee louse population regulation by honey bees is unknown, individual and social behaviors regulating V. destructor populations within colonies are not sufficient to maintain low levels of both B. pretoriensis and V. destructor. Sanitary measures were proposed, some of which are currently being applied to limit the spread of V. destructor across the island.