Map showing the sampling localities (numbers) for each host species of the Balkan Peninsula near the eastern coast of the Adriatic and Ionian Sea. (1) Trichonis Lake, Panetolio; (2) Spercheios River, Ypati; (3) Pineios River, Rongia – Valamandrio; (4) Sušik River, Drežnica; (5) Neda River, Giannitsochori; (6) Nezdravica River, Tihaljina; (7) Rečina River, Hutovo Blato Natural Park.