European Mosquito Bulletin, 22(2007), 5-9. Journal of the European Mosquito Control Association ISSN1460-6127 First Record of Aedes (Stegomyia) albopictus in the Netherlands Ernst-Jan Scholte1,2*, Frans Jacobs2,3, Yvonne-Marie Linton4, Eddy Dijkstra1, Joanne Fransen1 & Willem Takken2 1Plant Protection Service, Department of Entomology, P.O. Box 9102, 6700 HC Wageningen, the Netherlands. 2Laboratory of Entomology, Wageningen University and Research Centre, P.O. Box 8031, 6700 EH Wageningen, the Netherlands. 3PRI Plant Research International, P.O. Box 16, 6700 AA Wageningen, the Netherlands. 4Department of Entomology, Natural History Museum, Cromwell Road, London SW7 5BD, UK. *Email: [email protected] Abstract In the summer of 2005, Aedes (Stegomyia) albopictus (Stegomyia albopicta in Reinert et al., 2004) was found inside and around three different horticultural companies near Aalsmeer in the Netherlands. The species was identified both by morphology and ITS2- DNA sequencing. Although a few adults were also found outdoors, it remains unclear whether these were “escapees” or if indeed the species is reproducing outdoors in or near the site of introduction. This record constitutes the northernmost finding of Ae. albopictus in Europe to date at 52oN. The introduction is associated with the import of Dracaena plants, colloquially known as ‘lucky bamboo’, from China. Keywords: Aedes albopictus, Dracaena sanderana, lucky bamboo, Dengue, the Netherlands Introduction 2004), Switzerland (Flacio et al., 2006) Greece Aedes (Stegomyia) albopictus (Skuse, 1894) (Samanidou-Voyadjoglou et al., 2005), Serbia (Diptera: Culicidae) (Stegomyia albopictus in and Montenegro (Petric et al., 2006), Croatia Reinert et al., 2004) is commonly referred to (Petric et al., 2006), Bosnia and Herzegovina as the ‘Asian tiger mosquito’. This species is (Petric et al., 2006), and Slovenia (Petric et al., considered a serious threat to human health 2006; Schaffner, 2006). because of its potential to transmit at least 22 types of arboviruses (Mitchell, 1995a; Gratz, In July 2005, a routine inspection of a 2004) and other infectious agents including horticultural company (henceforth called Dirofilaria imitis (Cancrini et al., 2003; Company 1) in the municipality of Comiskey & Wesson, 1995). It is especially Haarlemmermeer was carried out by the Dutch notorious for its vectorial capacity of all four National Plant Protection Service (NPPO). serotypes of dengue (Mitchell, 1995a), which Company 1 had recently imported Dracaena is transmitted both horizontally and vertically sanderana, also known as ‘lucky bamboo’ or (Guo et al., 2004). Aedes albopictus was also ‘Ribbon Plants’ from China. The inspector circumstantially incriminated as the principal reported the presence of large numbers of an vector of Chikungunya virus in la Reunion and unknown mosquito species on the premises of other islands in the Indian Ocean, where a the company where the Dracaena plants were major epidemic of this arbovirus occurred in kept: a relatively small hall with doors that 2005 (Paganin et al., 2006). were left completely open wide to the outside. The inspector was bitten by several mosquitoes Aedes albopictus was originally indigenous to and described them as ‘aggressive’. No larvae South-East Asia, including parts of China, were found. The personnel of Company 1 and Korea, Japan, and islands of the Western of a neighbouring (non-horticulture) company Pacific and Indian Ocean. Range expansion in the same building mentioned that for several eastwards across Pacific islands during the weeks they had experienced severe mosquito early 20th century was mainly due to the nuisance and mosquito bites during daytime increased trade in used tyres, and, in recent working hours. This study was carried out in decades, it has spread to Africa, the Middle order to identify these mosquitoes. East, the Americas (north and south), and Europe (Knudsen, 1995; Mitchell, 1995b). In Materials & Methods Europe, the species has been reported from Following the initial inspection, specimens Albania (Adhami & Reiter, 1998), Italy were captured, tentatively identified as Ae. (Sabatini et al., 1990), France (Schaffner & albopictus and sent to the Natural History Karch, 2000; Schaffner et al., 2001), Spain Museum, London for morphological and (Roiz et al., 2006), Belgium (Schaffner et al., molecular verification. Molecular 5 Scholte et al. Aedes albopictus in the Netherlands identification was carried out by PCR Sampling was carried out approximately once amplification and sequencing of the nuclear every fortnight by visual inspection and by ITS2 sequences using the 5.8SF and 28SR using ‘counterflow’ traps (‘Liberty Plus’ – primers of Collins & Paskewitz (1996) American Biophysics Corp., North Kingstown, following the protocol listed in Linton et al. RI 02852, USA). The traps were used as a (2001). continuous monitoring device and were placed shortly after the first finding of Ae. albopictus. Results Until November 2005 traps were only placed All specimens tested were identified as Ae. outdoors, one at each company, 10-15 m from albopictus. Sequences obtained were 100% the main entrance to the hangar and identical to those entered for Aedes albopictus greenhouse, respectively. From November entries AY741376 and M95127, and varied 2005, an additional trap was placed indoors at only by a single base to AY741377. each company. The traps were emptied and checked for the presence of Ae. albopictus Subsequent visits of mosquito specialists of the approximately once every fortnight. The Dutch NPPO and of the Laboratory of results are presented in Table 1. Entomology of Wageningen University to the company to place traps and visually search for Discussion mosquitoes reconfirmed the presence of Ae. Aedes albopictus is mainly introduced into albopictus, but in contrast to the inspector’s new areas via the international trade in used reported massive abundance of mosquitoes in tyres (Knudsen, 1995). However, the Company 1, only few (<5) specimens were introduction of Ae. albopictus into the found. One month after the confirmation of Ae. Netherlands has been shown to be connected to albopictus in Company 1, this company moved the import of Dracaena sanderana plants, as to another location. Despite continued was reported in California in 2001 (Linthicum monitoring at the original site of the findings, et al., 2003; Madon et al., 2004). Both no other findings of Ae. albopictus were confirmed cases in California were linked to reported from company 1 until February 2006, sea-trailer import of these plants from southern when 2 adult mosquitoes were caught China. Dracaena sanderana is a popular outdoors, some 15 meters from the original site ornamental plant in Europe. The plants are of Company 1. transported in Perspex boxes containing a few centimetres of water. We propose that the A few weeks after this first report, similar mosquitoes reported from the Netherlands mosquito nuisance was reported from two derived from eggs that had been deposited near other Dracaena-importing companies, both in the water level, either on the plants or the the neighbouring municipality of Aalsmeer. Perspex boxes, while the plants were still in Companies 2 and 3 kept the Dracaena-plants southern China. in large greenhouses under controlled climatic conditions. The doors that connect the Since the region of southern China from which greenhouses with the outdoor environment the Dracaena plants originated is endemic for were usually kept closed, except during dengue (CDC, 2005), this introduction of Ae. on/offloading of trucks. At the initial survey of albopictus in the Netherlands could constitute Company 2 and Company 3, few Ae. health risks, both to the employees in the albopictus were collected, despite complaints infested greenhouses, and to inhabitants of the of mosquito nuisance, but shortly afterwards surrounding areas. Since dengue can be several larvae and adults of Ae. albopictus transmitted transovarially in Ae. albopictus were found in the greenhouse of Company 2. (Zhang & Zhang, 1996), the risk of dengue Once the presence of Ae. albopictus had been infection to humans in the Netherlands derives confirmed, this company applied chemical not only from mosquitoes that arrived from insecticides (type unknown) in an attempt to China already as adult mosquitoes, but also for control and contain the mosquitoes. In newborn generations. It is likely that Ae. Company 3, several adults were found, and albopictus will be able to survive in one larva. On two occasions at the end of greenhouses, but it is unclear whether it is able September, two adults were collected outdoors to reproduce in the natural climatic conditions of Company 3, some 20 meters from the of the Netherlands and whether it could entrance. Although Company 3 had sprayed establish itself. The distribution of Ae. chemical insecticides (larvicides? Or against albopictus in the north of Asia occasionally adults?) upon experiencing mosquito nuisance, reaches the -5°C isotherm. Even assuming a mosquitoes continued to be collected from conservative 0°C isotherm, this means that the Autumn 2005 through to the spring of 2006. species might become established in northern 6 European Mosquito Bulletin, 22(2007), 5-9. 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