First record and morphological characterization of an established population of Aedes (Hulecoeteomyia) koreicus (Diptera: Culicidae) in Germany.

Background: The East Asian mosquito species Aedes koreicus was recorded out of its native range for the first time in Belgium in 2008. Since then, several other European populations or single individuals have been observed throughout Europe with reports from Italy, Switzerland, European Russia, Slovenia, Germany and Hungary. The Italian population seems to be the only one that is expanding rapidly, so the Swiss population very likely derives from it.

Results: In a surveillance program for invasive mosquito species, a single larva of Ae. koreicus was found in a cemetery vase in 2016 in the city of Wiesbaden, Germany. In the following year the finding was confirmed and an established population could be proven over an area of about 50 km. The morphological identification of the first larva was confirmed by sequencing of a region within the nad4 sequence. A study of adult females showed that the morphological characteristics of this population are not identical to the populations from Belgium and Italy. The eggs and larvae were found together with Aedes j. japonicus in the same breeding sites and ovitraps, as well as with other indigenous mosquito species such as Culex pipiens/Culex torrentium, Aedes geniculatus and Anopheles plumbeus.

Conclusions: Since the newly discovered population in Germany shows different morphological characteristics to the populations in Belgium and Italy, it seems to originate from an independent introduction. It remains unknown how the introduction took place. A further spread similar to the one in northern Italy can be assumed for the future due to similar climatic conditions.