Francis Schaffner, Christian Kaufmann, Daniel Hegglin and Alexander Mathis

Institute of Parasitology, Swiss Reference Laboratory for Vector Entomology, University of Zurich, Zurich, Switzerland, Medical and Veterinary Entomology, 2009, 23, 448–451

Complaints about a biting pest led to the recognition of invasive Aedes (Finlaya) japonicus japonicus (Theobald) (Diptera: Culicidae) in Central Europe. Larval collections from cemetery vases revealed a colonized area of approximately 1400 km2 in northern Switzerland spreading into bordering Germany, suggesting that the mosquito has been established in this region for several years. Within this range, larvae of Ae. japonicus were recovered from more containers than the most common resident culicid species Culex pipiens. Possible introduction sites (used tyre yards and international airports) revealed few or no larvae, and the mode of introduction remains unclear. Given the vector potential of this species for arboviruses, implementation of surveillance and control measures should be considered.

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VBORNET comment: 2009-11-13
This paper is related to the ProMED-mail post [Archive Number 20090830.3044; Published Date 30-AUG-2009; Subject PRO/AH> Mosquito, imported – Switzerland]. It gives the first finding of proliferation and spread of an invasive mosquito in Central Europe (northern to the Alps). Aedes japonicus is known as an invasive species (ISGG, 2009) and as a competent laboratory vector of several arboviruses (Williges et al. 2008) including West Nile virus for which it is suspected to play a role as bridge vector. In Europe, a few larvae of this species were identified in France in 2000 on a storage yard of imported used tyres (Schaffner et al., 2003), but this introduction was eliminated (unpublished data). Since 2002, this species has repeatedly been observed within a restricted area of two neighbouring used tyre yards in Belgium (Versteirt et al., 2009), but interestingly, the species has not spread there. If there was evidence of introduction by used tire trade in these countries, no obvious source of introduction could be identified in Switzerland. The field study did not reveal any indication that Ae. albopictus has established in Switzerland north of the Alps and the earlier record of this species (Wyman et al., 2008) was due to a misidentification of a single specimen from a photograph. Authors propose to survey the species by investigating cemeteries, determining a vase index (percentage of colonized vases). They propose to implement further studies which should monitor the rapidity of its spread as well as determine the bionomics of this species, in order to assess its vector potential for native and exotic pathogens in the local environment. This is particularly of relevance as Ae. japonicus is breeding in urbanized environments. They assume that invasive as well as vector potential render this species a potential threat for animal and human health, and justify the implementation of preventive surveillance and control measures.