## 2 Materials and Methods
### Collection of the Required Data  
The information on the geographic coordinates of the apiaries registered on a national level was replicated at the National Reference Center for Beekeeping at the Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe) using the download tools (a dedicated IT procedure based on synchronous web service protocols) made available by the BDNA. The BDNA is based on a software used by the Italian local health units personnel to input apiary data. For each apiary, the BDNA software stores the coordinates of its location together with the number of beehives and swarms/nuclei, as well as information, such as the beekeeper's name and address. According to the Italian legislation [8], between November and December of each year, the Veterinary Services of the local health units perform a census of the apiaries present in the Italian territory. The census is aimed at updating the information about new beekeepers, beekeepers that ceased their activities, the location of apiaries, the number of beehives and swarms/nuclei present in the apiaries. Moreover, every year, the local health units have to select 1% of apiaries located in their territory to inspect and check the information stored in the BDNA. The BDNA software is built for compulsory input of the geographical coordinate values of an apiary location every time a new beekeeper is registered or the location of apiaries is changed. To insert or update the geographical coordinates in the BDNA software, two methods are offered, the direct and the indirect method. The direct method is based on the use of GPS: the beekeepers by means of a GPS device (even a smartphone, which nowadays offer applications with  
Figure 1: Flow chart representing the mapping procedure for calculating the mating areas. the GPS functionalities) record the coordinates and inform the local health unit about the apiary location, providing the information that is imputed in the software by the operator. The indirect method is based on the use of digital cartography. The BDNA software allows the operator to open a new frame in the computer screen where a digital map offered by Google appears together with some functionalities, which allows the geolocation of the point where the apiaries are located. The result of the geolocation operation is the calculation of the apiaries' geographical coordinates. The BDNA software uses as geographical coordinate system the WGS84 (description about the WGS84 coordinate system can be found in the EPSG web site: [[https://epsg.org/home.html](https://epsg.org/home.html)]([https://epsg.org/home.html](https://epsg.org/home.html)) (accessed on 18 May 2021) and the coordinates are expressed in decimal degree (i.e., \"GG, dddddd\" where \"G\" means degree, and \"d\" decimal degree). For the geospatial information about wetlands located in the Italian territory, the Soil Cover classification of the CORINE Land Cover (CLC) inventory was used (information about the CORINE project can be found in the Copernicus project web site: [[https://land.copernicus.eu/pan-european/corine-land-cover](https://land.copernicus.eu/pan-european/corine-land-cover)]([https://land.copernicus.eu/pan-european/corine-land-cover](https://land.copernicus.eu/pan-european/corine-land-cover)) (accessed on 10 May 2021). The 2018 version of the CLC was used (v.2020_20u1 [[https://land.copernicus.eu/pan-european/corine-land-cover/clc2018](https://land.copernicus.eu/pan-european/corine-land-cover/clc2018)]([https://land.copernicus.eu/pan-european/corine-land-cover/clc2018](https://land.copernicus.eu/pan-european/corine-land-cover/clc2018)), accessed on 18 May 2021). Given the CLC data, all areas belonging to the first level CLC class 4 (humid environment) or 5 (water environment) were derived. For the information about areas higher than 1500 m a.s.l.