Six gel-and five water-transported Dracaena braunii shipments originating from the South coast of China were screened for exotic mosquito species during a surveillance project on exotic vectors in Belgium. In November 2013, a live Aedes (Stegomyia) albopictus larva was detected in a gel substrate. This is the first direct evidence of the importation of Ae. albopictus on gel-transported Lucky bamboo. It also confirms that the importation risk of Ae. albopictus by transport of ornamental bamboo plants remains. In addition to the registration of appropriate biocides, a structured and permanent surveillance programme is needed in Belgium to allow for the early detection of invasive mosquito species and the timely implementation of control measures. JournalThe Federal Agency for the Safety of the Food Chain (FASFC)http://e-m-b.orgam201

De Witte, Jacobus C.

Deblauwe, Isra

Demeulemeester, Julie

Hendy, Adam

Jansen, Famke

Madder, Maxime

UPSpace at the University of Pretoria

Vol. 32     JOURNAL OF THE EUROPEAN MOSQUITO CONTROL ASSOCIATION    14   First interception of Aedes (Stegomyia) albopictus  in Lucky bamboo shipments in Belgium  Julie Demeulemeester1*, Isra  Deblauwe1, Jacobus  De Witte1, Famke Jansen1,  Adam Hendy1, Maxime Madder1,2  1Veterinary Entomology Unit, Vector Biology Group, Department of Biomedical Sciences, Institute of Tropical Medicine, Nationalestraat 155, 2000 Antwerp, Belgium 2Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, Pretoria, South Africa. *corresponding author: jdemeulemeester@itg.be  First published online 9th May 2014  Abstract: Six gel-and five water-transported Dracaena braunii shipments originating from the South coast of China were screened for exotic mosquito species during a surveillance project on exotic vectors in Belgium. In November 2013, a live Aedes (Stegomyia) albopictus larva was detected in a gel substrate. This is the first direct evidence of the importation of Ae. albopictus on gel-transported Lucky bamboo. It also confirms that the importation risk of Ae. albopictus by transport of ornamental bamboo plants remains. In addition to the registration of appropriate biocides, a structured and permanent surveillance programme is needed in Belgium to allow for the early detection of invasive mosquito species and the timely implementation of control measures. Journal of the European Mosquito Control Association 32: 14-16, 2014  Keywords: Tiger mosquito, Aedes albopictus, Dracaena braunii, biocide legislation, surveillance, Belgium   Introduction The Asian tiger mosquito, Aedes (Stegomyia) albopictus (Skuse, 1894), is considered to be the most invasive mosquito species in the world (Gratz, 2004). It is a known vector of Dirofilaria, and also arboviruses including dengue, chikungunya, Eastern equine encephalitis, La Crosse, Venezuelan equine encephalitis, West Nile and Japanese encephalitis (Gratz, 2004). It was originally indigenous to South-East Asia, but has since spread to Africa, the Middle East, the Americas and Europe (Knudsen, 1995). Aedes albopictus first appeared in Belgium on 31st October 2000 at a used tyre company in Vrasene, near Antwerp, when a single pupa and larva were collected (Schaffner et al., 2004). Following further inspections and short term surveillance projects between 2001 and 2012, Ae. albopictus was not considered to be established in Belgium, and was assumed to have died-out naturally (Schaffner, unpublished data; Deblauwe et al., 2012; Versteirt et al., 2012). However, in July 2013 a male Ae. albopictus was collected at the same tyre company as the previous record (Boukraa et al., 2013). Since then, 18 specimens have been found at the same company in Vrasene by the Institute of Tropical Medicine, suggesting a new and persistent introduction of this species. Individuals of this species are primarily introduced into new geographic areas via the international trade in used tyres (Knudsen, 1995), and through the import of Lucky bamboo (Dracaena braunii) plants. The latter route has been responsible for introducing Ae. albopictus into California, U.S. (Madon et al., 2003) and the Netherlands (Scholte et al., 2007). In Belgium, the introduction of this mosquito species has only so far been detected through the import of used tyres. Following the collection of the first Ae. albopictus specimens from a Lucky bamboo nursery in the Netherlands (Scholte et al., 2007), it was proposed that transporting the plants on gel rather than in water would provide a more effective way to reduce the presence of Ae. albopictus in Lucky bamboo imports. In California, shipments of Dracaena spp. in standing water were prohibited following the identification of Ae. albopictus, and the import of plants has since only been permitted on gel (Madon et al., 2003). This appears to have prevented further importations of Ae. albopictus in Lucky bamboo (Scholte et al., 2008). However, in the Netherlands, 70% of nurseries where adult Ae. albopictus have been found, claimed to have imported plants on gel only (Scholte et al., 2008). Other means to prevent further importations of Ae. albopictus were proposed by the mandatory treatment of shipping containers with larval biocides shortly before shipment. The Lucky bamboo commodities act (DWJZ/SWW-3039313) was created after the collection of more than 500 Ae. albopictus specimens at nurseries in the Netherlands between 2005 and 2009. The act states that “Lucky Bamboo plants shall only enter the territory of the Netherlands free of Asian tiger mosquitoes. The plants have to be transported in sealed containers.  These containers must be opened in a secluded area. The plants shall not leave the room unless they have been adequately treated with both an appropriate biocide to make the plants free of Asian tiger mosquito larvae, and an appropriate biocide to make the plants free of adult Asian tiger mosquitoes.” (WTO, 2011).  In Belgium and the Netherlands however, the biocide legislation prohibits the use of biocides against invasive mosquitoes. An exemption on this legislation is therefore necessary before certain larvicidal products can be used. In June 2013, the exemption expired for the Netherlands. Since this expiration, some Lucky bamboo shipments destined for Dutch import companies, along with all shipments destined for a plant import company in Belgium, have been deviated via the port of Antwerp.  Here we present the first direct evidence of Ae. albopictus being imported into Belgium on gel-transported Lucky bamboo.  Vol. 32    JOURNAL OF THE EUROPEAN MOSQUITO CONTROL ASSOCIATION          15          Materials and Methods Eleven shipments of Dracaena braunii were inspected for the presence of mosquito larvae and eggs, on eight days, between August 2013 and January 2014. In five of these shipments, plants were transported in trays containing water, and in the remaining six, plants were transported in plastic bags containing hygroscopic gel. These bags were fixed around the base of plants to prevent the roots from drying out. One of the shipments was destined for a Lucky bamboo import company in the Netherlands, and the other ten shipments for a Belgian company in the province of Oost-Vlaanderen. Upon arrival at the border inspection post of the Federal Agency for the Safety of the Food Chain (FASFC), trays of Lucky bamboo were randomly selected for sampling of water or gel. Between 12 and 60 samples were collected from each shipment (Table 1), and the samples were taken to the Institute of Tropical Medicine (ITM), Antwerp, for analysis. Morphological identification of mosquito larvae was carried out using taxonomic keys (Schaffner et al., 2001; ECDC 2012) and confirmed by PCR. The ITS2 region of the rDNA gene was amplified using 5.8S (5’-ATCACTCGGCTCGTGGATCG-3’) and 28S (5’-ATGCTTAAATTTAGGGGGTAGTCAC-3’), universal primers which flank the ITS2 gene (Collins et al., 1987; Djadid et al., 2007). A reverse primer specific for the Ae. albopictus 28S sequence was used to perform a semi-nested PCR (R28Salbo: 5’-TTGCGGGTGTTTTGTGTGTCGTC-3’) (De Jong et al., 2009). DNA was run on 2% agarose gel. Gels were stained with ethidium bromide and bands were visualized by UV trans-illumination  Results On the 21st November 2013, a live third instar Ae. albopictus larva was found in a shipment of Lucky bamboo transported on gel (Table 1). The shipment originated from Guangzhou, a town in the south-eastern province of Guandong in China, and was intended for delivery to the import company in Belgium. No other mosquito larvae or eggs were detected in any of the remaining samples.  Table 1: Inspected Lucky bamboo shipments with inspection date, destination, mode of transport, number of samples inspected and number of positive samples for Ae. albopictus.  Date Destination Water/gel # inspected samples # positive samples 19 Sep-13 The Netherlands Gel 30 0 25 Sep-13 Belgium Gel 30 0 25 Sep-13 Belgium Water 12 0 03 Oct-13 Belgium Water 38 0 09 Oct-13 Belgium Water 38 0 31 Oct-13 Belgium Gel 30 0 21 Nov-13 Belgium Gel 60 1(larva) 27 Nov-13 Belgium Gel 30 0 27 Nov-13 Belgium Gel 30 0 27 Nov-13 Belgium Water 30 0 11 Dec-13 Belgium Water 25 0  Discussion and conclusion At most, 60 gel-filled bags were screened from each shipment of Lucky bamboo. This represents only 1/200th of the total cargo of each container. The likelihood that more gel-filled bags contain mosquito larvae is therefore high. The limited data presented in this study indicates that there is still a risk of importing Ae. albopictus eggs or larvae into Europe via consignments of Lucky bamboo, even on a gel substrate. Although no water is found in the gel-bags, the gel is well hydrated and appears to offer a suitable medium for the short-term survival of mosquito larvae, and possibly for the eclosion of mosquito eggs during transport. Hygroscopic gel is likely a better substrate for transporting Lucky bamboo than water, but it does not alleviate the risk of importing a dangerous disease vector. The ability of Ae. albopictus to colonise new geographic areas has led to its predicted spread in Europe (Medlock et al., 2012). Using a Geographic Information Systems (GIS)-based model, a study in the U.K. revealed that abiotic risk factors would permit establishment of Ae. albopictus throughout large parts of lowland U.K. (Medlock et al., 2006). A parallel study concluded that climatic conditions do not appear to preclude establishment of Ae. albopictus in the Netherlands (Takumi et al., 2009). Indeed some temperate strains of Ae. albopictus have been proven to survive the cold winters in the northern hemisphere through the production of cold-resistant eggs (Severini et al., 2008). Although the strains of Ae. albopictus imported with Dracaena braunii are tropical, outdoor establishment of the mosquito might be possible if no preventative and curative control measures are taken in nurseries housing Lucky bamboo in the Netherlands (Scholte et al., 2010; Takumi et al., 2009) and other temperate countries like Belgium. No control measures are currently in place in Belgium owing to the difficulty in obtaining an exemption of the biocide legislation, which increases the risk of Ae. albopictus becoming established. We therefore urge the registration of appropriate insecticides for use against invasive mosquitoes. We also recommend the implementation of a structured and permanent surveillance programme in Belgium, similar to those already in use in neighbouring countries (e.g. CNEV 2012; VWA 2013).   Vol. 32    JOURNAL OF THE EUROPEAN MOSQUITO CONTROL ASSOCIATION          16          Acknowledgements The shipments have been inspected for the presence of Ae. albopictus as part of a surveillance project of exotic vectors and pathogens in Belgium. The project was financed by the Federal Agency for the Safety of the Food Chain (FASFC).We wish to thank the FASFC for financing this surveillance project and the Lucky Bamboo import company for its collaboration.  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First interception of Aedes (Stegomyia) albopictus in Lucky bamboo shipments in Belgium

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First interception of Aedes (Stegomyia) albopictus in Lucky bamboo shipments in Belgium

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