European beewolf (Philanthus triangulum) will expand its geographic range as a result of climate warming

Climate change is an important driver of the spread of apiary pests and honeybee predators. These impact on one of the economically most important pollinators and thus pose serious threats to the functioning of both natural ecosystems and crops. We investigated the impact of the predicted climate change in the periods 2040–2060 and 2060–2080 on the potential distribution of the European beewolf Philanthus triangulum, a specialized honeybee predator. We modelled its potential distribution using the MaxEnt method based on contemporary occurrence data and bioclimatic variables. Our model had an overall good performance (AUC = 0.864) and the threshold of occurrence probability, assessed as the point with the highest sum of sensitivity and specificity, was at 0.533. Annual temperature range (69.5%), mean temperature in the warmest quarter (12.4%), and precipitation in the warmest quarter (7.9%) were the principal bioclimatic variables significantly affecting the potential distribution of the European beewolf. We predicted the potential distribution shifts within two scenarios (optimistic RPC4.5 and pessimistic RCP8.5) and three Global Circulation Models (HadGEM2-ES, IPSL-CM5A-LR, and MPI-SM-LR). Both optimistic and pessimistic scenarios showed that climate change will significantly increase the availability of European beewolf potential niches. Losses of potential niches will only affect small areas in southern Europe. Most of the anticipated changes for the period 2060–2080 will already have occurred in 2040–2060. The predicted range expansion of European beewolf suggests that occurrence and abundance of this species should be monitored.