Rapid spread and population genetics of Aedes japonicus japonicus (Diptera: Culicidae) in southeastern Europe (Croatia, Bosnia and Herzegovina, Serbia)

Abstract

The Asian bush mosquito, Aedes japonicus japonicus (Theobald, 1901), a potential vector of several pathogens, has recently established in North America and Central Europe. In 2013, it was found on the Slovenian-Croatian border, and during the following years, it emerged in more and more counties of northwestern Croatia. Surveillance of Ae . j . japonicus and other invasive mosquito species was subsequently extended both spatially and temporally in Croatia and neighbouring Bosnia and Herzegovina and Serbia. Mosquito collections were conducted in 2017 and 2018, based on adult trapping through dry ice-baited CDC traps and BG-Lure-baited BG-Sentinel traps, larval sampling through dippers and nets, and ovitrapping. Aedes j . japonicus specimens from collected samples were subjected to population genetic analysis by comparing microsatellite signatures and nad 4 DNA sequences between sampled locations and with data previously obtained from more western European distribution areas. Aedes j . japonicus immature stages were found at 19 sites in Croatia, two sites in Bosnia and Herzegovina and one site in Serbia. In Croatia, four new counties were found colonised, two in the east and two in the south of the previously known distribution area. A spread of 250 km could thus be documented within five years. The findings in Bosnia and Herzegovina and Serbia represent the first records of Ae . j . japonicus in these countries. Genetic analysis suggests at least two introduction events into the surveyed area. Among the locations analysed, Orahovica can be considered a genetic border. The individuals collected west of this point were found to be similar to samples previously collected in the border regions of Southeast Germany/Austria and Austria/Slovenia, while the specimens from more eastern Croatian localities, together with those from Bosnia and Herzegovina and Serbia, were genetically different and could not be assigned to a probable origin. Thus, introduction from Central Europe, possibly by vehicular traffic, into the study area is likely, but other origins, transportation routes and modes of entry appear to contribute. Further dispersal of Ae . j . japonicus to other parts of southeastern Europe is anticipated.

Oviposition of Aedes japonicus japonicus (Diptera: Culicidae) and associated native species in relation to season, temperature and land use in western Germany

“…This subspecies started to spread in North America in the late 1990s [ 12 ] and to colonise Europe from 2000 onwards [ 13 ]. The most recent findings were reported from Spain [ 14 ], Serbia and Bosnia and Herzegovina [ 15 ]. Due to its geographic origin, this mosquito is well adapted to the moderate climate of Germany, where it has been considered established since 2008 [ 16 ].…”

At the tip of an iceberg: citizen science and active surveillance collaborating to broaden the known distribution of Aedes japonicus in Spain

“…albopictus and Ae. aegypti [ 22 ]. Most of the detections presented here were based on larval collection and egg-laying in ovitraps.…”

“…Autonomous flight has been suggested as the main driver for the 100-km expansion in dispersal range in Austria over a 7-year period, as well as its expansion in Hungary [ 23 , 40 ] and its spread of up to 250 km in Croatia in only 5 years [ 22 ]. However, the role of active flight abilities is unclear.…”

“…Aedes japonicus was detected in Austria and Slovenia in 2011 [ 18 ]; in 2012, the first records were registered in both the Netherlands [ 19 ] and Hungary [ 18 ]. Definitive establishment in France [ 20 ] as well as in Croatia [ 21 ] was confirmed in 2013, with a subsequent spread to Bosnia-Herzegovina and Serbia by the following years [ 22 ]. In 2015 the species was found in Italy [ 18 ] and Liechtenstein [ 23 ] and in 2020 in Romania [ 24 ].…”

Diapause characterisation and seasonality of Aedes japonicus japonicus (Diptera, Culicidae) in the northeast of France

“…This invasive mosquito began spreading in the United States in 1998 [ 1 ] and started to colonise Europe two years later, in 2000 [ 39 ]. Nowadays, in Europe, the species is found in France [ 39 ], Belgium [ 54 ], Switzerland [ 40 ], Germany [ 5 , 20 , 55 ], Austria [ 44 ], Slovenia [ 44 ], the Netherlands [ 17 ], Luxembourg, Liechtenstein, Spain, Croatia, Hungary, Italy [ 36 ], Bosnia and Herzegovina, and Serbia [ 19 ]. The East Asian Bush mosquito has therefore been able to colonise a vast area and various latitudes in only 20 years.…”