Intra-island distribution of the wild bee species of Madeira Island, habitat preferences and flower-visiting behaviour (Hymenoptera, Apoidea, Anthophila)

Abstract

The aim of this study was to analyse the intra-island distribution pattern, the habitat preferences, and the flower-visiting behaviour of the wild bee species of Madeira Island. The total dataset from Madeira Island includes 2,226 data from 491 localities (1,029 with flower visits on 112 plant taxa belonging to 39 plant families). We sampled a total of 1,595 data from 1989 to 2022. Additionally, 392 data came from collections of institutions and museums checked by the authors, supplemented by 227 data from the literature, eight data from private collections, and five from further reliable observations. In all, we detected 18 wild bee species, which reflect the complete species pool of permanently established species as well as single observations. Anthidium manicatum and Xylocopa violacea are here included as new species for Madeira Island. In some cases, new taxonomic findings have been added to the checklist published by Kratochwil et al. (2018). These are listed under ‘status’. The distribution of the wild bee species was documented on a base of square-grid cells (1 km x 1 km) based on the military map of the Madeira Archipelago (2004). We were able to analyse data from wild bee specimens on 251 representative square-grid cells (30% of the whole area with 826 square-grid cells), which reflect the proportion of the occurring thermo-, hygro- and vegetation series. Among the frequently occurring species, Bombus terrestris lusitanicus, Andrena wollastoni, and Lasioglossum wollastoni show the largest distribution areas, whereas most of the populations of Amegilla quadrifasciata maderae, Bombus r. ruderatus, Andrena maderensis, Osmia madeirensis, and O. niveata colonise the warmer zones. Species-specific habitat preferences were characterised according to the bioclimatic vegetation-series system of Rivas-Martínez (1996, 2009). Flower-visiting preferences were documented on the plant-species level. Six of the identified wild bee species and one subspecies can be classified as endemic to Madeira Island or Madeira Archipelago, eight species as introduced or probably introduced, and three species as native or probably native. The endemic wild bee species make up large numbers of individuals. This is also true for Bombus terrestris lusitanicus (native, the most frequently recorded species) and Lasioglossum v. villosulum (probably native, the third most frequently recorded species).