First detection of Vespa velutina nigrithorax (Hymenoptera: Vespidae) in the Balearic Islands (Western Mediterranean): a challenging study case

Abstract

The yellow-legged hornet, Vespa velutina nigrithorax is an Invasive Alien Species introduced into Europe in 2004, and is currently present in France, Italy, Spain, Portugal, Germany, and Belgium. It was also recently introduced in the United Kingdom and Switzerland. Here we present the first detection of V. velutina in the westernmost Mediterranean islands (Majorca, Balearic archipelago). In October 2015, a specimen of hornet, which was later identified as V. velutina, was sent to the laboratory of Zoology at the University of the Balearic Islands by a beekeeper from the locality of Soller (northwest of Majorca). After the identification, and in coordination with the local authorities, an intensive survey was implemented in the area of first detection using sticky traps baited with protein and nest detection by directly observing the flight route of adult hornets from two or three feeding points. The first nest was detected on 30th October 2015 and was entirely removed. The next year, nine other nests were located from August to November 2016 in the same area and again, all of them were removed entirely. It is the first report on an island of destroying nests as a means of controlling the spread, a scenario very different to mainland Europe. All nests were detected in evergreen tree species (pines, holm oaks, and common cypress) in the “Serra de Tramuntana”, a mountain range located in the north-west of the island of Majorca (3667 km2), which is situated 176 km off the mainland. Considering the presumably early stage of the invasion of V. velutina in Majorca, the size of the island, and the confinement of the detection area, we consider that this species could be eradicated if resources and a specific program for eradication in Majorca are implemented in coordination with all involved partners.