New Localities and Habitat Suitability Modelling for the Riverine Water Bug Aphelocheirus aestivalis (Fabricius, 1794) (Heteroptera: Aphelocheiridae) in Northern and Eastern Bulgaria

摘要

Aphelocheirus aestivalis is a stenobiotic species with low dispersion ability. It is the only member of the family Aphelocheiridae found in most of Europe. Hydromorphological changes and water pollution threaten its subpopulations. Considering the vulnerability of the species, more accurate data about its occurrence and geographic distribution are needed. We present here 65 localities of A. aestivalis in 27 rivers in Bulgaria, including the southernmost record of the species in Europe (Maritsa River near the town of Svilengrad). Of those, 23 are in the Danube River Basin, two flow directly into the Black Sea and two belong to the Aegean Sea watershed. In the subpopulations of A. aestivalis in the Lower Danube River (Bulgarian section) and the rest of the studied rivers, all developmental stages were present during all sampling seasons. Remarkable downstream drift of nymphs and adults of A. aestivalis was observed in the Danube River (Bulgarian section) during spring high water levels. In order to identify potential suitable habitats for the species in the Black Sea Basin, we built a habitat suitability model using Maxent software. Our models suggested (with high probability) that there could be suitable habitats in the basins of six more rivers in the Black Sea Basin with no current records of A. aestivalis.