A new focus of Aedes japonicus japonicus (Theobald, 1901) (Diptera, Culicidae) distribution in Western Germany: rapid spread or a further introduction event?

Abstract

BackgroundThe Asian bush mosquito, Aedes japonicus japonicus, a potential vector of several viruses, was first detected in Germany in 2008 on the Swiss-German border. In the following years, this invasive species apparently succeeded in establishing populations in southern Germany and in spreading northwards. In 2011, its distribution area already covered large areas of the federal state of Baden-Wurttemberg, and its northernmost German collection point was reported to be close to Stuttgart. Several independent submissions to our laboratories of Ae. j. japonicus specimens in July 2012, originating from the same area in the federal state of North Rhine-Westphalia, western Germany, prompted us to carry out an immediate surveillance in this region in the expectation of finding a further distribution focus of Ae. j. japonicus in Germany.MethodsAfter inspecting the places of residence of the collectors of the submitted mosquito specimens, all kinds of water containers in 123 cemeteries in surrounding towns and villages were checked for mosquito developmental stages. These were collected and kept to produce adults for morphological species identification. One specimen per collection site was identified genetically by COI sequence analysis.ResultsAedes j. japonicus adults and immature stages were found in 36 towns/villages that were checked (29%) over an area of approximately 2,000 km2 in southern North Rhine-Westphalia and northern Rhineland Palatinate. The species could not be demonstrated further south when monitoring towards the northernmost previous collection sites in southern Germany. It therefore remains to be elucidated whether the species has entered western Germany from the south, from Belgium in the west where it has been demonstrated to occur locally since 2002, or through a new introduction.ConclusionsAedes j. japonicus is obviously much more widely distributed in Germany than previously thought. It appears to be well adapted, to have a strong expansion tendency and to replace indigenous mosquito species. Thus, a further spread is anticipated and elimination seems hardly possible anymore. The vector potency of the species should be reason enough to thoroughly monitor its future development in Germany.

Aedes albopictus and Aedes japonicus - two invasive mosquito species with different temperature niches in Europe

“…Both species are considered invasive in many countries worldwide, including North America and Africa. More recently, they have also become established in western Europe [13, 20, 21]. Due to ongoing introductions and projected climate change, both species are predicted to continue their spread in Europe and will therefore remain the subject of surveillance and monitoring programmes [22].…”

Occurrence and Spread of the Invasive Asian Bush Mosquito Aedes japonicus japonicus (Diptera: Culicidae) in West and North Germany since Detection in 2012 and 2013, Respectively

“…j . japonicus were unambiguously identified by specific morphological and behavioural characteristics [13]. This identification in the field was later confirmed in the laboratory genetically by CO1 barcoding [31, 32] of alcohol-fixed larvae from every site considered positive.…”

Field evaluation of baited traps for surveillance of Aedes japonicus japonicus in Switzerland

“…As previously observed (Schaffner et al , ; Werner & Kampen, ), cemeteries provide numerous artificial habitats for container‐breeding mosquitoes in many newly invaded areas (Vezzani, ) and are particularly useful for assessing the presence and abundance of Ae. j. japonicus (Schaffner et al , ; Kampen et al , ; Zielke et al , ). The absence of egg collection in CDC ovitraps reported by Andreadis et al () for sites at which adult gravid females were trapped may reflect the separation observed between mosquito adult and larval habitats or the low attractiveness of the seed germination paper employed as an oviposition substrate.…”